Patent Publication Number: US-2022222063-A1

Title: Portable device communicating with charger and operating method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0004936, filed on Jan. 13, 2021, and Korean Patent Application No. 10-2021-0063619, filed on May 17, 2021, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to an electronic device, and more particularly, to a portable device and operating method thereof. 
     2. Description of the Related Art 
     Wireless earphones are a device for outputting sound from a wirelessly received source signal. Wireless earphones may include a communication module such as a Bluetooth module, to perform short-range wireless communication, and a battery to supply driving power to the communication module. As a dedicated charger for charging the battery of the wireless earphones, a charging case in the form of storing the wireless earphones and also charging the same may be used. 
     SUMMARY 
     Embodiments are directed to a portable device, including: a power line communication module configured to perform power line communication with an external device; a memory module configured to store firmware data; and a controller configured to control the power line communication module and the memory module. The power line communication module may transmit an update initiation signal commanding to initiate a firmware update, to the external device, transmit the firmware data to the external device, and transmit an update end signal commanding to end the firmware update to the external device, according to a first response signal transmitted by the external device. 
     Embodiments are also directed to a portable device, including: a connection pin configured to be connected to an external device; a power line communication module configured to perform power line communication with the external device via the connection pin; a memory module configured to store data; and a controller configured to control the power line communication module and the memory module. The power line communication module may receive updated firmware data from the external device, and provide the updated firmware data to the controller. The controller may perform a validity check based on the updated firmware data in a firmware update mode, and control the memory module to store the updated firmware data in the memory module based on a result of the validity check. 
     Embodiments are also directed to an operating method of a portable device for performing power line communication with an external device via a connection pin, the operating method including: providing an update initiation signal commanding to initiate a firmware update, to the external device; providing firmware data, which has been previously stored in the portable device, to the external device; and providing an update end signal commanding to end the firmware update to the external device, in response to a response signal transmitted by the external device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail example embodiments with reference to the attached drawings in which: 
         FIG. 1  is a diagram for describing first through third portable devices according to an example embodiment; 
         FIG. 2  is a diagram for describing first and second portable devices according to an example embodiment, in further detail; 
         FIG. 3  is a diagram for describing a first operating method of first through third portable devices, according to an example embodiment; 
         FIG. 4  is a diagram for describing a second operating method of first through third portable devices, according to an example embodiment; 
         FIG. 5  is a diagram illustrating an example of structures of data and a response signal transmitted between first and second portable devices; 
         FIG. 6  is a diagram for describing a preamble period and a data period; 
         FIG. 7  is a diagram for describing modulation of signals transmitted between first and second portable devices, according to an example embodiment; 
         FIG. 8  is a diagram for describing portable devices according to another example embodiment; 
         FIG. 9  is a diagram for describing portable devices according to another example embodiment; 
         FIG. 10  is a diagram for describing portable devices according to another example embodiment; 
         FIG. 11  is a diagram for describing portable devices according to another example embodiment; and 
         FIG. 12  is a diagram for describing portable devices according to another example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a diagram for describing first through third portable devices according to an example embodiment. 
     Referring to  FIG. 1 , a first portable device  100  may include a connection pin T 1 . The first portable device  100  may transmit data or a command signal to a second portable device  200  via the connection pin T 1 . Also, the first portable device  100  may receive data or a response signal from the second portable device  200  via the connection pin T 1 . The connection pin T 1  of the first portable device  100  may be connected to a connection pin T 2  of the second portable device  200 . The term “connected” described in the present specification may refer to a direct contact or indirect contact between the plurality of connection pins T 1  and T 2 . The first portable device  100  may transmit data or a notification signal to a third portable device  300  wirelessly. Also, the first portable device  100  may wirelessly receive a request signal from the third portable device  300 . The first portable device  100  may be a wearable device such as smart glasses, a smart watch, a smart band, or wireless earphones (or earbuds). 
     The second portable device  200  may include the connection pin T 2  and an external voltage pin Tin. The second portable device  200  may receive an external voltage Vin via the external voltage pin Tin. For example, the second portable device  200  may receive the external voltage Vin corresponding to an alternating current source, which is a power source for homes, through the external voltage pin Tin. In another implementation, the second portable device  200  may receive the external voltage Vin from another power supply unit (e.g., a computer or an auxiliary battery) through the external voltage pin Tin. In another implementation, the second portable device  200  may receive the external voltage Vin wirelessly from the outside. The second portable device  200  may be, for example, a charging device. 
     The first portable device  100  and the second portable device  200  may perform power line communication (PLC). PLC refers to a communication technique for transmitting power and data via a power line. 
     The third portable device  300  may perform wireless communication with the first portable device  100 . The wireless communication may be, for example, Bluetooth. The third portable device  300  may be a computing device, for example, a laptop computer, a tablet PC, or a mobile phone (or smartphone). 
     The first portable device  100  may be referred to as an external device with respect to the second portable device  200  and the third portable device  300 . Likewise, the second portable device  200  may be referred to as an external device with respect to the first portable device  100  and the third portable device  300 . The third portable device  300  may be referred to as a host with respect to the first portable device  100  and the second portable device  200 . A “portable device” described in the present specification may be referred to as a “mobile equipment,” “a portable equipment,” “a mobile device,” or the like. 
       FIG. 2  is a diagram for describing first and second portable devices according to an example embodiment, in further detail. 
     Referring to  FIG. 2 , the first portable device  100  and the second portable device  200  may be connected to each other via first and second connection pins T 1 _ 1 , T 1 _ 2 , T 2 _ 1 , and T 2 _ 1 . As the first portable device  100  and the second portable device  200  are connected to each other, a power line may be implemented between the first connection pin T 1 _ 1  of the first portable device  100  and the first connection pin T 2 _ 1  of the second portable device  200  and a power line may be implemented between the second connection pin T 1 _ 2  of the first portable device  100  and the second connection pin T 2 _ 2  of the second portable device  200 . The first portable device  100  and the second portable device  200  may perform PLC via the power lines. A power line implemented between the first connection pin T 1 _ 1  of the first portable device  100  and the first connection pin T 2 _ 1  of the second portable device  200  may be a line through which a positive voltage or current is transferred. Also, a power line implemented between the second connection pin T 1 _ 2  of the first portable device  100  and the second connection pin T 2 _ 2  of the second portable device  200  may be a line through which a negative voltage or current is transferred. However, the number of power lines and voltages and currents transferred via each power line may be varied. As the first and second portable devices  100  and  200  perform power line communication (PLC) via the first and second connection pins T 1 _ 1 , T 1 _ 2 , T 2 _ 1 , and T 2 _ 1 , there is no need to additionally provide connection pins for performing data communication, and thus, the manufacturing costs may be reduced, and the sizes of the first and second portable devices  100  and  200  may be reduced. 
     The first portable device  100  may include a power line communication module  110 , a controller  120 , a power management integrated circuit  130 , a battery  140 , a wireless communication module  150 , and a memory module  160 . 
     The power line communication module  110  may receive power from the second portable device  200  in response to the control by the controller  120 . The power line communication module  110  may transmit or receive data to or from the second portable device  200  in response to the control by the controller  120 . The power line communication module  110  may modulate a current signal to be transmitted to the second portable device  200 . The power line communication module  110  may demodulate a voltage signal received from the second portable device  200 . 
     The power line communication module  110  may transmit an update initiation signal to the second portable device  200 . The update initiation signal may be a signal command initiation of a firmware update. Firmware update may refer to update of firmware of the second portable device  200 . 
     After the update initiation signal is transmitted to the second portable device  200 , the power line communication module  110  may transmit an erase command signal to the second portable device  200 . The erase command signal may be a signal commanding to erase firmware data stored in the second portable device  200 . 
     After the erase command signal is transmitted to the second portable device  200 , the power line communication module  110  may transmit firmware data to the second portable device  200 . The firmware data may include data including information about firmware of the second portable device  200  and may be referred to as a firmware image. 
     The power line communication module  110  may transmit an update end signal to the second portable device  200  according to a response signal from the second portable device  200 . The update end signal may be a signal commanding to end firmware update. This will be described in more detail later with reference to  FIG. 3 . 
     The controller  120  may control the overall operation of the first portable device  100 . The controller  120  may control the power management integrated circuit  130  to perform a charging operation based on power received from the second portable device  200 . The controller  120  may control the power line communication module  110  to perform a communication operation on the second portable device  200 . The controller  120  may control the wireless communication module  150  to perform a communication operation with respect to the third portable device  300 . The controller  120  may control the memory module  160  to store data received from the second portable device  200 . The controller  120  may include a micro control unit (MCU), a processor such as a central processing unit (CPU), etc. 
     The power management integrated circuit  130  may charge the battery  140  by using different charging methods according to a charging state of the battery  140 . For example, the power management integrated circuit  130  may charge the battery  140  by using a pre-charging method, a constant-current method, a constant-voltage method, or a trickle charging method, according to the increase in a charging voltage of the battery  140 . The power management integrated circuit  130  may charge the battery  140  by using the pre-charging method when the battery  140  is over-discharged. The power management integrated circuit  130  may charge the battery  140  by using the constant current method and the constant voltage method when the battery  140  is in a normal state. The power management integrated circuit  130  may charge the battery  140  by using the trickle method when the battery  140  is in a fully-charged state. 
     The battery  140  may be charged with power supplied from the power management integrated circuit  130 . A charging state of the battery  140  may include an over-discharged state, a normal state, and a fully-charged state. The battery  140  may be implemented using, e.g., a rechargeable secondary battery or a fuel cell. 
     The wireless communication module  150  may perform wireless communication with the third portable device  300 . To perform a firmware update, the wireless communication module  150  may receive firmware data for execution in the second portable device  200 , from the third portable device  300 , and provide the received firmware data to the controller  120 . The wireless communication module  150  may receive a signal for requesting a firmware update from the third portable device  300 , and provide the received signal to the controller  120 . 
     The power line communication module  110  may receive another response signal from the second portable device  200 , and the controller  120  may generate a notification signal for requesting display of a message on the third portable device  300 , in response to the other response signal. The wireless communication module  150  may transmit the notification signal to the third portable device  300 . 
     The memory module  160  may include a volatile memory  161  and a non-volatile memory  162 . The volatile memory  161  may include dynamic random access memory (DRAM), static random access memory (SRAM), or the like. The non-volatile memory  162  may store data or signals regardless of whether power is supplied or not. The non-volatile memory  162  may include, e.g., a NAND flash memory, NOR flash memory, or the like. 
     The memory module  160  may store data. The memory module  160  may store first firmware data executed in the first portable device  100 . The memory module  160  may store second firmware data executed in the second portable device  200 . The volatile memory  161  may temporarily store a signal received from the second portable device  200  and data transmitted by the third portable device  300 , only during a power receiving period. The second firmware data executed in the second portable device  200  may be stored in the non-volatile memory  162  before the signal for firmware update described above is transmitted to the first portable device  100 . 
     The second portable device  200  may include a power line communication module  210 , a controller  220 , a power management integrated circuit  230 , a battery  240 , a display  250 , and a memory module  260 . The second portable device  200  may include external voltage pins Tin_ 1  and Tin_ 2 , via which an external voltage Vin may be received from the outside. For example, the external voltage pins Tin_ 1  and Tin_ 2  may receive the external voltage Vin from an alternating current source, which is a power source for homes or other power supply units (e.g., a computer or an auxiliary battery). The second portable device  200  may also receive the external voltage Vin wirelessly from the outside. 
     The power line communication module  210  may transmit power to the first portable device  100  in response to the control by the controller  220 . The power line communication module  210  may receive data (e.g., firmware data) or a signal (e.g., an update initiation signal, an erase signal, or an update end signal) from the first portable device  100  in response to the control by the controller  220 . The power line communication module  210  may transmit a response signal to the first portable device  100  in response to the control by the controller  220 . The power line communication module  210  may modulate a voltage signal to be transmitted to the first portable device  100 . The power line communication module  210  may demodulate a current signal received from the first portable device  100 . 
     The controller  220  may control the overall operation of the second portable device  200 . For example, the controller  220  may control the power management integrated circuit  230  such that power is supplied to the second portable device  200 . The controller  220  may control the power line communication module  210  to perform a communication operation on the first portable device  100 . The controller  220  may control the display  250  to perform a display operation of displaying a charge amount of the battery  240 , a state of the second portable device  200 , or the like. The controller  220  may control the memory module  260  to store data received from the first portable device  100 . The controller  220  may include a processor such as an MCU or a CPU. 
     The controller  220  may load firmware data from the memory module  260  when the second portable device  200  is booted, and execute a user mode based on the firmware data. 
     The controller  220  may enter a firmware update mode from the user mode in response to an update initiation signal received by the power line communication module  210 . In the firmware update mode, the controller  220  may perform a validity check based on updated firmware data provided by the first portable device  100 . The validity check may be a check on whether firmware data provided by the first portable device  100  is valid data. The validity check may be, for example, a cyclic redundancy check. 
     The controller  220  may control the memory module  260  such that updated firmware data is stored in the memory module  260  according to a result of the validity check. The updated firmware data may be stored in a non-volatile memory  262  included in the memory module  260 , and firmware data that was previously stored in the non-volatile memory  262  may be processed as invalid. 
     The controller  220  may monitor whether the first and second connection pins T 2 _ 1  and T 2 _ 2  are connected to the first connection pins T 1 _ 1  and T 1 _ 2  of the first portable device  100 , respectively, and may generate a response signal for notifying release of the connection pins T 1 _ 1 , T 1 _ 2 , T 2 _ 1 , and T 2 _ 2 . The power line communication module  210  may transmit the response signal to the first portable device  100 . In response to the response signal, the first portable device  100  may transmit, to the third portable device  300 , a notification signal for requesting display of a message on the third portable device  300 . 
     The controller  220  may compare a charge amount of the battery  240  with a preset reference amount, and may control the power management integrated circuit  230  to block the external voltage Vin based on whether the charge amount of the battery  240  is greater than the preset reference amount. 
     The power management integrated circuit  230  may charge the battery  240  based on the external voltage Vin received from the outside. The power management integrated circuit  230  may generate a charging voltage to be provided to the battery  240 , based on the external voltage Vin. The power management integrated circuit  230  may include a converter (not shown) generating a conversion voltage from the external voltage Vin revived from the outside via the external voltage pins Tin_ 1 , Tin_ 2  or from a battery voltage of the battery  240 . The converter may be a DC-DC converter. The converter may be a step-up converter converting a relatively low external voltage Vin or a battery voltage into a higher conversion voltage (e.g., a boost converter), or a step-down converter converting a relatively high external voltage Vin or a battery voltage into a lower conversion voltage (e.g., a buck converter). 
     The battery  240  may be charged based on a charging voltage supplied from the power management integrated circuit  230 . 
     The memory module  260  may include a volatile memory  261  and the non-volatile memory  262 , like the memory module  160  included in the first portable device  100 . 
     In the present example embodiment, the first portable device  100  transmitting firmware data to the second portable device  200  is described, but the second portable device  200  may be implemented to transmit firmware data of firmware of the first portable device  100  via PLC. 
       FIG. 3  is a diagram for describing a first operating method of first through third portable devices, according to an example embodiment. 
     Referring to  FIG. 3 , a first portable device PD 1  illustrated in  FIG. 3  may correspond to the first portable device  100  illustrated in  FIG. 1 , and a second portable device PD 2  illustrated in  FIG. 3  may correspond to the second portable device  200  illustrated in  FIG. 1 , and a third portable device PD 3  illustrated in  FIG. 3  may correspond to the third portable device  300  illustrated in  FIG. 1 . 
     In the present example embodiment, in operation S 10 , the third portable device PD 3  transmits a request signal to the first portable device PD 1  via wireless communication. The request signal generated by the third portable device PD 3  may be a signal for requesting to update firmware of the second portable device PD 2 . Referring to  FIG. 2 , for example, a user may command initiation of a firmware update in an application or software of the third portable device PD 3 , and the third portable device PD 3  may transmit a request signal to the first portable device  100  via wireless communication, and the wireless communication module  150  included in the first portable device  100  may receive the request signal from the third portable device PD 3 . 
     In operation S 20 , the first portable device PD 1  transmits an update initiation signal to the second portable device PD 2  in response to the request signal. Referring to  FIG. 2 , for example, the controller  120  included in the first portable device  100  may generate an update initiation signal in response to a request signal, and provide the update initiation signal to the power line communication module  110 , and may control the power line communication module  110  to transmit the update initiation signal to the second portable device  200  via PLC. 
     In operation S 30 , the second portable device PD 2  changes from a user mode to a firmware update mode in response to the update initiation signal. Referring to  FIG. 2 , for example, the controller  220  included in the second portable device  200  may enter the firmware update mode in response to an update initiation signal provided from the power line communication module  210 . 
     In operation S 21 , the first portable device PD 1  provides an erase command signal after the update initiation signal is transmitted. Referring to  FIG. 2 , for example, the controller  120  may generate an erase command signal, provide the same to the power line communication module  110 , and control the power line communication module  110  to transmit the erase command signal. The power line communication module  110  may transmit the erase command signal to the second portable device PD 2  before the firmware data is provided to the second portable device  200 . 
     In operation S 31 , the second portable device PD 2  erases previously stored firmware data in response to the erase command signal. Referring to  FIG. 2 , for example, the power line communication module  210  may receive the erase command signal after the update initiation signal is received, and provide the erase command signal to the controller  220 . In response to the erase command signal, the controller  220  may control the non-volatile memory  262  to erase firmware data stored in the non-volatile memory  262 . 
     In operation S 22 , the first portable device PD 1  transmits the updated firmware data to the second portable device PD 2  after the erase command signal is transmitted. Referring to  FIG. 2 , for example, the power line communication module  110  may transmit the updated firmware data to the second portable device  200 . In this case, the firmware data to be transmitted to the second portable device  200  may be divided or split and transmitted in units of data packets having a first size. For example, firmware data to be transmitted to the second portable device  200  may be divided into 1-byte data packets, and the 1-byte data packets may be sequentially transmitted to the second portable device  200 . 
     In operation S 32 , the second portable device PD 2  temporarily stores the firmware data that is divided or split and transmitted in units of data packets. Referring to  FIG. 2 , for example, the controller  220  may control the volatile memory  261  to temporarily store a 1-byte data packet received through the power line communication module  210 , in the volatile memory  261 . 
     In operation S 23 , the first portable device PD 1  determines whether a predefined number of data packets have been transmitted to the second portable device PD 2 . The predefined number may be, for example, 8, and when 8 data packets are transmitted to the second portable device PD 2  (operation S 23 , YES), the first portable device PD 1  transmits first check data regarding a cyclic redundancy check performed on the data packets, to the second portable device PD 2  (operation S 24 ). That is, each time 8-byte data packets are transmitted to the second portable device PD 2 , the first check data may be transmitted to the second portable device PD 2 . On the other hand, when 8 data packets are not transmitted to the second portable device PD 2  (operation S 23 , NO), operation my return to operation S 22 . 
     In operation S 33 , the second portable device PD 2  generates second check data based on the temporarily stored firmware data. 
     Then, in operation S 34 , the second portable device PD 2  checks whether a validity check, that is, a cyclic redundancy check, is a pass, by using the first check data and the second check data). Whether the cyclic redundancy check is a pass may be determined based on whether the first check data and the second check data match. The controller  220  may control the non-volatile memory  262  to store updated firmware data in the non-volatile memory  262  according to a result of the validation check. According to this, by checking whether there are errors in a data packets, errors in firmware data may be reduced. 
     When a result of the cyclic redundancy check is a pass (operation S 34 , YES), in operation S 35  the second portable device PD 2  performs a write operation. The write operation may be an operation of storing data in a non-volatile memory. Referring to  FIG. 2 , for example, in response to a result of the validation check, the result being a pass, the controller  220  may control the non-volatile memory  262  to store updated firmware data by transmitting 8-byte data packets and a write command/address to the non-volatile memory  262 . 
     On the other hand, when the result of the cyclic redundancy check is a fail (operation S 34 , NO), the second portable device PD 2  releases the temporarily stored firmware data in operation S 36 . The release of the temporarily stored firmware data may be an operation that erases or flushes data stored in a volatile memory. Referring to  FIG. 2 , for example, in response to the result of the validation check being a fail, the controller  220  may control the volatile memory  261  to delete 8-byte data packets temporarily stored in the volatile memory  261 . 
     In operation S 37 , the second portable device PD 2  transmits a response signal indicating a pass or a fail of the cyclic redundancy check to the first portable device PD 1 . Referring to  FIG. 2 , for example, the controller  220  may control the power line communication module  210  to transmit a response signal indicating that the result of the validation check is a fail, to the first portable device  100 . 
     In operation S 25 , the first portable device PD 1  checks whether the response signal is a pass. 
     When the response signal indicates a fail (operation S 25 , NO), the operation returns to operation S 22  and firmware data is divided and transmitted in units of 1 byte-data packets. 
     On the other hand, when the response signal indicates a pass (operation S 25 , YES), the first portable device PD 1  determines whether all firmware data is transmitted in operation S 26 . Until all the firmware data is transmitted, the above-described operations S 22  to S 25  and S 32  to S 37  are performed. 
     When the response signal indicates a pass (operation S 25 , YES), the first portable device PD 1  transmits an update end signal to the second portable device PD 2  in operation S 27 . Referring to  FIG. 2 , for example, when the response signal indicates a pass, the controller  120  may generate an update end signal and provide the same to the power line communication module  110 , and control the power line communication module  110  to transmit the update end signal. 
     On the other hand, when the response signal indicates a fail (operation S 25 , NO), the operation returns to operation S 22  and the controller  120  may control the power line communication module  110  to transmit the firmware data stored in the non-volatile memory  162  back to the second portable device  200 . Also when the firmware data is transmitted again, the firmware data may be transmitted in units of 1 byte data packets. Meanwhile, the power line communication module  210  may receive the firmware data again after the response signal is transmitted to the first portable device  100 . 
     In operation S 38 , the second portable device PD 2  resets with the stored firmware data, i.e., new firmware data, in response to the update end signal, and executes a user mode. 
     According to the above, firmware of a portable device may be updated simply and quickly compared to firmware update done by visiting a service center or through a separate zig. 
       FIG. 4  is a diagram for describing a second operating method of first through third portable devices, according to an example embodiment. 
     Referring to  FIG. 4 , operations S 100 , S 200 , and S 300  are respectively the same as operations S 10 , S 20 , and S 30  described above, and thus, the description thereof will be omitted. 
     In operation S 310 , the second portable device PD 2  monitors whether a connection pin provided in the second portable device PD 2  and a connection pin provided in the first portable device PD 1  are connected to each other. Referring to  FIG. 2 , for example, the controller  220  included in the second portable device  200  may monitor whether the first and second connection pins T 2 _ 1  and T 2 _ 2  of the second portable device  200  and the first and second connection pins T 1 _ 1  and T 1 _ 2  of the first portable device  100  are respectively in contact with each other. 
     When the connection between the connection pins is abnormal or bad (operation S 310 , NO), the second portable device PD 2  transmits a first response signal to the first portable device PD 1  in operation S 320 . In response to the first response signal, the first portable device PD 1  transmits a first notification signal indicating that the contact between the connection pins is bad, to the third portable device PD 3  in operation S 210 . The third portable device PD 3  may display a first message in response to the first notification signal. For example, the first message may indicate “reconnect the connection pins to complete firmware update” or the like. 
     On the other hand, when the connection of the connection pins is normal (operation S 310 , YES), the second portable device PD 2  monitors whether a charge flag has a first set value in operation S 330 . The charge flag may indicate whether the power management integrated circuit  230  receives the external voltage Vin and charges the battery  240 . The charge flag may have a first set value (e.g., true) or a second set value (e.g., false). The charge flag having the first set value may indicate that the power management integrated circuit  230  is charging the battery  240 . The charge flag having the second set value may indicate that charging of the battery  240  is stopped. The first portable device PD 1  may stop a wireless communication operation on the third portable device PD 3 . For example, the first portable device PD 1  may turn off Bluetooth of the third portable device PD 3 . As the wireless communication is stopped, the influence of noise by the third portable device PD 3  may be reduced. 
     When the charge flag does not have the first set value (operation S 330 , NO), the second portable device PD 2  transmits a second response signal to the first portable device PD 1  in operation S 340 . In response to the second response signal, the first portable device PD 1  transmits a second notification signal indicating that firmware is being updated, to the third portable device PD 3  in operation S 220 . The third portable device PD 3  may display a second message in response to the second notification signal. For example, the second message may indicate “updating firmware” or the like. 
     On the other hand, when the charge flag has the first set value (operation S 330 , YES), the second portable device PD 2  monitors whether a charge amount of the battery  240  is greater than a first reference amount in operation S 350 . 
     When the charge amount of the battery  240  is not greater than the first reference amount (operation S 350 , NO), the second portable device PD 2  displays battery information about the battery  240 , such as the charge amount, in operation S 361 . Referring to  FIG. 2 , for example, the controller  220  may control the display  250  to display battery information. 
     When the charge amount of the battery  240  is greater than the first reference amount (operation S 350 , YES), the second portable device PD 2  sets a set value of the charge flag to the second set value in operation S 362 . Referring to  FIG. 2 , for example, the controller  220  may control the power management integrated circuit  230  to stop a charging operation by setting the set value of the charge flag to the second set value. Accordingly, the amount of heat generated in the second portable device PD 2  may be reduced, and the influence of noise caused by the external voltage Vin during PLC may be reduced. Accordingly, the time for transmitting the firmware data may be shortened. The first portable device PD 1  may transmit a notification signal informing that the firmware update is to restart, to the third portable device PD 3 . 
     After each of operations S 361  and S 362  is performed, operation S 310  is performed again. 
     Referring again to operation S 330 , when the charge flag does not have the first set value (operation S 330 , NO), because the charge flag has the second set value, the charge amount of the battery  240  is reduced. After the second response signal is transmitted to the first portable device PD 1 , the second portable device PD 2  monitors whether the charge amount of the battery  240  is less than a second reference amount (operation S 370 ). The first reference amount may be greater than the second reference amount. 
     When the charge flag has the second set value (operation S 370 , YES), the second portable device PD 2  sets the value of the charge flag to the first set value in operation S 380 . When the charge flag has the first set value, the battery  240  may be charged as described above. 
     On the other hand, when the charge flag does not have the second set value (operation S 370 , NO), the second portable device PD 2  transmits a third response signal to the first portable device PD 1  in operation S 390 . 
     In operation S 240 , the first portable device PD 1  transmits firmware data to the second portable device PD 2  in response to the third response signal. 
     In operation S 400 , the second portable device PD 2  performs a firmware update operation. The firmware update operation according to operation S 400  may indicate that operations S 22  to S 25  and S 32  to S 37  described above with reference to  FIG. 2  are performed. 
       FIG. 5  is a diagram illustrating an example of structures of data and a response (ACK) signal transmitted between first and second portable devices. 
     Referring to  FIG. 5 , a data structure may be divided into a preamble, a header, and data. Each of the preamble, header, and data may include a plurality of fields. 
     In an example embodiment, a period of a preamble may have five periods. In addition, as all of preamble signals are toggled in each period, all logic values of the preamble signals may have a value of “1.” 
     The header may include a start field, a header type field, and a header parity field. The start field may include one bit and may correspond to information indicating a start of data transmission. The header type field indicates a type of data and may include one or more bits (e.g., four bits). The header parity field is used to determine validity of transmitted header information and may include one bit. 
     The data may include a data message field, a data parity field, a data checksum field, and an end field. The data message field may include actual data having a plurality of bits. The data parity field is used to determine the validity of data and may include one bit. The data checksum field is used to detect errors in data and may include a plurality of bits. The end field is used to indicate an end of data transmission and may include one bit. 
     A header of an update initiation signal may be expressed as “0x1”, and data of the update initiation signal may be expressed as “0 x10.” A header of an erase command signal may be expressed as “0x1”, and the data of the erase command signal may be expressed as “0x44.” A header of a data packet may be expressed as “0xA.” A header of check data may be expressed as “0xF.” A header of an update end signal may be expressed as “0xE,” and data of the update end signal may be expressed as “0x10.” 
     In order to increase the reliability of data transmission/reception, the second portable device  200  may transmit the response signal ACK. The response signal ACK may be transmitted once after data reception. The response signal ACK may have a shorter field structure than data. Accordingly, the time for transmitting the response signal ACK may be shortened. 
     The response signal ACK may include a preamble, a start field, a header type field, and a header parity field. The preamble may be the same as that described above. The start field may include one bit and may correspond to information indicating a start of transmission of the response signal ACK. The header type field may include at least one bit (e.g., four bits) and may indicate a type of the response signal ACK. The header parity field may include one bit and may be transmitted to determine the validity of header information. 
     A response signal indicating a pass may be expressed as “0x55.” A response signal indicating a fail may be expressed as “0xFF.” 
     On the other hand, in transmission/reception of data or the response signal ACK, when expressing one bit, when there is a toggle within one data cycle, logic “1” may be represented, and when there is no toggle, logic “0” may be represented. Also, because the preamble period is a period in which a frequency and duty are detected, the frequency and duty are not to be changed within the preamble period until data transmission/reception is performed. 
       FIG. 6  is a diagram for describing a preamble period and a data period. 
     In describing the example embodiment illustrated in  FIG. 6 , it is assumed that the first portable device  100  transmits data, and the second portable device  200  receives data. 
     Referring to  FIG. 6 , before data is transmitted, the second portable device  200  may enter a preamble period, and the second portable device  200  may receive a preamble signal that is toggled at least once in the preamble period.  FIG. 2  illustrates an example in which the preamble signal is toggled once, and the second portable device  200  may detect a frequency and duty of the preamble signal through the preamble signal that is toggled at least once. 
     As an example, when a duty ratio of the preamble signal is set to 1:1, the frequency (or cycle (T)) of the preamble signal is detected by detecting a logic high period or a logic low period of the preamble signal. The second portable device  200  may perform various setting operations related to data reception based on the detected frequency of the preamble signal. As an example, the cycle T of the preamble signal corresponds to a data period including one bit in a data transmission period, and the second portable device  200  may perform an internal setting operation to determine data in each data cycle according to the detected frequency. 
     Next, the second portable device  200  may determine data D 1 , D 2 , and D 3  based on a preset condition in each data cycle. As an example, a timing (or period) for determining whether toggling of a voltage signal (or an internal signal) exists in each data cycle in each data period may be set based on a duty of a preamble signal, and when the toggling of the voltage signal is present in each data period, data of logic high may be determined, whereas, when there is no toggling of the voltage signal, data of logic low may be determined. 
       FIG. 3  illustrates an example in which a preamble period includes a plurality of periods. While  FIG. 3  illustrates an example in which a preamble period includes three periods and a preamble signal is transmitted in each period, various numbers of preamble signals may be transmitted. 
     A preamble signal may be transmitted to the second portable device  200  through a power line, and a signal applied to the power line before a preamble period may have an initial state. Thereafter, as the preamble period starts, a preamble signal may be transmitted in each of first to third periods, and the first to third periods have the same time period, and duties D of the preamble signals may be identical to each other. The second portable device  200  may detect a frequency and duty of the preamble signal, based on the preamble signal received in each of the first to third periods. 
     The frequency and duty of the preamble signal may be variously set, and a detection operation thereof may also be performed using various methods. For example, as preamble signals having the same frequency and duty are transmitted in each of the first to third periods, the frequency and duty of the preamble signals may be detected. Alternatively, at least one of a frequency and a duty of preamble signals in each of the first to third periods may be different from the other, and the second portable device  200  may calculate an average value of the frequencies and duties of the preamble signals in a plurality of periods to detect the frequencies and duties of the preamble signals. 
     An example of an operation of transmitting and detecting a preamble signal will be described as below. 
     The second portable device  200  transmitting power may provide a voltage signal, and a level of the voltage signal transmitted through the power line may swing at an appropriate level that does not affect an operation of the second portable device  200  that receives the power. The second portable device  200  may perform voltage modulation to provide a preamble signal, and the frequency (or cycle) of the preamble signal may have a value that is slower than a limit clock (e.g., system clock) of the second portable device  200 . For example, the frequency of the limit clock of the second portable device  200  may be 20 times or more fast than the frequency of the preamble signal. 
     Although an initial state before the preamble period is shown as logic low, the preamble signal may be toggled once in each of a plurality of periods of a preamble period. Also, the second portable device  200  may perform a voltage modulation operation such that duties of preamble signals in a plurality of periods are the same. The first portable device  100  may analyze the preamble signal by using the limit clock and detect a frequency (or cycle) and duty of the preamble signal by using the analyzed preamble signal. 
       FIG. 7  is a diagram for describing modulation of signals transmitted between first and second portable devices, according to an example embodiment. 
     Referring to  FIG. 7 , a current signal Ic may be a signal transmitted by the first portable device  100  to the second portable device  200  via PLC. A voltage signal Vc may be a signal transmitted by the second portable device  200  to the first portable device  100  via PLC. 
     A first communication period ETC may be a period in which the first portable device  100  modulates the current signal Ic to transmit firmware data or check data to the second portable device  200 . The first communication period ETC may be divided into a firmware data transmission period FWTP and a check data transmission period CRCTP. A second communication period CTE may be a period in which the second portable device  200  modulates the voltage signal Vc to transmit a response signal to the first portable device  100 . 
     A logic level of the current signal Ic may be higher than a reference level ref. The current signal Ic may be modulated during the first communication period ETC. The modulated current signal Ic may be a signal in the form of a pulse having a certain logic level. During the first communication period ETC, each time the current signal Ic is modulated in the firmware data transmission period FWTP, firmware data of a 1 byte data packet may be transmitted to the second portable device  200 . Referring to  FIG. 7 , for example, each of first through eighth current pulses CP 1  through CP 8  may correspond to a 1 byte-data packet with respect to firmware data. It may be understood that 8 byte-data packets are transmitted to the second portable device  200   c  via the first through eighth current pulses CP 1  through CP 8 . During the first communication period ETC, a ninth current pulse CP 9  may be formed in the check data transmission period CRCTP. The ninth current pulse CP 9  may correspond to check data. 
     Meanwhile, a logic level of the voltage signal Vc may be lower than the reference level ref. The voltage signal Vc may have a form of first through eighth pulses DP 1  through DP 8  by the current signal Ic modulated during the first communication period ETC. The voltage signal Vc may be modulated during the second communication period CTE. A voltage pulse VP in the second communication period CTE may correspond to a response signal. 
       FIG. 8  is a diagram for describing portable devices according to another example embodiment. 
       FIG. 8  illustrates first and second earbuds  11  and  12 , a cradle  20  for the first and second earbuds  11  and  12 , a power source  30  connected to the cradle  20 , and a host device  40  performing wireless communication with the first and second earbuds  11  and  12 . 
     Hereinafter, description of details regarding the example embodiment of  FIG. 8  provided above may be omitted. 
     Each of the first and second earbuds  11  and  12  may correspond to the first portable device  100  illustrated in  FIG. 1 . The cradle  20  may correspond to the second portable device  200  illustrated in  FIG. 1 . The host device  40  may correspond to the third portable device  300  illustrated in  FIG. 1 . 
     The first and second earbuds  11  and  12  may perform wireless communication with the host device  40 , and output sound from a source signal received from the host device  40 . The first and second earbuds  11  and  12  may perform mutual wireless communication with each other. For example, the first and second earbuds  11  and  12  may perform mutual wireless communication for the purpose of synchronization, transferring of states, or the like. Each of the first and second earbuds  11  and  12  may include a battery that is charged by power supplied from the cradle  20 , and may efficiently and completely perform power line communication with the cradle  20 . Accordingly, in the first and second earbuds  11  and  12 , in addition to a pair of terminals for charging, an additional terminal for communicating with the cradle  20  may be omitted, and the first and second earbuds  11  and  12  and the cradle  20  may have a simple structure. In particular, due to the compact size of the first and second earbuds  11  and  12  and the cradle  20 , the simple structure of the first and second earbuds  11  and  12  and the cradle  20  may provide various advantages. 
     The cradle  20  may function as a charger of the first and second earbuds  11  and  12  and may be portable. For example, the cradle  20  may include a battery  28 , and may charge the first and second earbuds  11  and  12  from power provided by the battery  28 . In addition, the cradle  20  may include a third terminal T 23  and a fourth terminal T 24  to be connected to the power source  30 , and the first and second earbuds  11  and  12  may be charged with power provided by the power source  30  to the battery  28 . The cradle  20  may function as a case for the first and second earbuds  11  and  12 . For example, the cradle  20  may have an internal structure in which the first and second earbuds  11  and  12  are seated, and may include a cover covering the first and second earbuds  11  and  12 . 
     Referring to  FIG. 8 , the cradle  20  may include a first modem  21 , a second modem  22 , a power management integrated circuit (PMIC)  24 , and the battery  28 . 
     The first modem  21  may perform power line communication with the first earbud  11 . 
     The second modem  22  may perform power line communication with the second earbud  12 . 
     The PMIC  24  may provide power (supplied from power provided from the power source  30  and/or the battery  28 ) to the first and second earbuds  11  and  12 . For example, the power source  30  may provide a 5V DC voltage based on a universal serial bus (USB) interface, and the PMIC  24  may generate a voltage and/or a current for charging the battery  28 , from the 5V DC voltage, and generate a voltage and/or current for charging the first and second earbuds  11  and  12 . 
     The host device  40  may be any device that provides a source signal to the first and second earbuds  11  and  12  through wireless communication. 
       FIG. 9  is a diagram for describing portable devices according to another example embodiment. For convenience of description, an example embodiment will now be described by using only one power line PL. 
     Referring to  FIG. 9 , a first portable device  50  may correspond to the first portable device  100  illustrated in  FIG. 1 , the first earbud  11  illustrated in  FIG. 8 , or the second earbud  12  illustrated in  FIG. 8 . A second portable device  60  may correspond to the second portable device  200  illustrated in  FIG. 1  or the cradle  20  illustrated in  FIG. 8 . 
     The first portable device  50  may include a connection pin T 1 , a variable impedance circuit  51 , a controller  52 , a PLC modem  53 , a battery  54 , a PMIC  55 , and a wireless transceiver  56 . The variable impedance circuit  51 , the controller  52 , the PLC modem  53 , the battery  54 , the PMIC  55 , and the wireless transceiver  56  may be mounted on a printed circuit board. The PMIC  55  may manage power of the battery  54 . 
     The wireless transceiver  56  may perform wireless communication with a host device  70 . For example, the wireless transceiver  56  may include a Bluetooth module and may receive data from the host device  70 . The wireless transceiver  56  of the first portable device  50  may provide data received from the host device  70  to the second portable device  60  via power line communication. 
     The second portable device  60  may include a connection pin T 2 , an external voltage pin Tin, a variable impedance circuit  61 , a controller  62 , a PLC modem  63 , a battery  64 , and a PMIC  65 . In another implementation, the second portable device  60  may include the variable impedance circuit  61 , the controller  62 , the PLC modem  63 , the battery  64 , and the PMIC  65 . The PMIC  65  may manage power of the battery  64 . 
       FIG. 10  is a diagram for describing portable devices according to another example embodiment. 
     Referring to  FIG. 10 , a first portable device  80  may correspond to the first portable device  100  illustrated in  FIG. 1 , the first earbud  11  illustrated in  FIG. 8 , the second earbud  12  illustrated in  FIG. 8 , or the first portable device  50  illustrated in  FIG. 9 . A second portable device  90  may correspond to the second portable device  200  illustrated in  FIG. 1 , the cradle  20  illustrated in  FIG. 8 , or the second portable device  60  illustrated in  FIG. 9 . 
     The first portable device  80  may include a connection pin T 1 , a charging circuit  81 , a battery  82 , a power line communication module  83 , a control circuit  84 , and an impedance circuit  85 . The charging circuit  81  may be a linear charger, and may be implemented as a charging integrated circuit (IC). The control circuit  84  may enable the charging circuit  81  in a charging period, and may charge the battery  82  based on power received through a power line PL. Also, in a data reception period, the control circuit  84  may disable the charging circuit  81 , and the first portable device  80  may operate based on power of the battery  82 . The battery  82  may be charged based on power received in a data transmission period. 
     The second portable device  90  may include a connection pin T 2 , an external voltage pin Tin, a converter  91 , a battery  92 , a power line communication module  93 , and a control circuit  94 . The converter  91  may generate a voltage Vc converted from the external voltage Vin received through the external voltage pin Tin or from a voltage of the battery  92 . The converter  91  may include a switching regulator, and may include a boost converter and/or a buck converter and a buck-boost converter as a DC-DC converter. The converter  91  may charge the battery  92  based on the external voltage Vin. 
     The power line communication module  83  of the first portable device  80  may include a voltage demodulator  83 _ 1  and a current modulator  83 _ 2 , and may further include a current source (not shown). The current modulator  83 _ 2  may perform current modulation under the control by the control circuit  84 . The current source may generate a modulated current signal (e.g., a current pulse), and the current signal may be output through the connection pin T 1 . The voltage demodulator  83 _ 1  may demodulate a voltage signal received through the connection pin T 1  and provide the demodulated signal to the control circuit  84 . 
     The power line communication module  93  of the second portable device  90  may include a current demodulator  93 _ 1  and a voltage modulator  93 _ 2 . The control circuit  94  may control the current demodulator  93 _ 1  and the voltage modulator  93 _ 2 . The voltage modulator  93 _ 2  may generate a modulated voltage signal under the control by the control circuit  94 , and the voltage signal may be output through the connection pin T 2 . The voltage modulator  93 _ 2  may include a linear regulator, such as a low drop-out (LDO) regulator. The current demodulator  93 _ 1  may demodulate a current signal received through the connection pin T 2  and provide the demodulated signal to the control circuit  94 . 
       FIG. 11  is a diagram for describing portable devices according to another example embodiment. 
     Referring to  FIG. 11 , an earbud  410  may correspond to the first portable device  100  illustrated in  FIG. 1 , and a cradle  420  may correspond to the second portable device  200  illustrated in  FIG. 1 . 
     The earbud  410  may include a control circuit  411 , a voltage demodulator  412 , and a current modulator  413 . The voltage demodulator  412  may include a filter  412 _ 1  and an amplifier  412 _ 2 . 
     The cradle  420  may include a control circuit  421 , an analog-to-digital converter (ADC)  422 , and an LDO regulator  423 . The ADC  422  may perform current demodulation. The LDO regulator  423  may perform voltage modulation. 
     In the earbud  410 , the filter  412 _ 1  of the voltage demodulator  412  may remove noise by blocking a specific frequency component of a voltage signal received through the power line PL, and provide the filtered voltage signal to the amplifier  412 _ 2 . The amplifier  412 _ 2  may generate a signal having a logic high level or a logic low level by amplifying the voltage signal and provide the same to the control circuit  411 . The control circuit  411  may identify the information transmitted by the cradle  420  based on the signal received from the amplifier  412 _ 2 , and by controlling the current modulator  413  to transmit the information to the cradle  420 , the control circuit  411  may generate a modulated current signal that is transmitted through the power line PL. 
     In the cradle  420 , the ADC  422  may generate a digital signal from a current signal received through the power line PL and provide the same to the control circuit  421 . The control circuit  421  may identify information transmitted by the earbud  410  based on the digital signal. By controlling the LDO regulator  423 , the control circuit  421  may generate a modulated voltage signal transmitted through the power line PL. 
       FIG. 12  is a diagram for describing portable devices according to another example embodiment. 
     Referring to  FIG. 12 , the first portable device  100  is the same as described above. 
     Each of a first pin P 1  of the first portable device  100  and a second pin P 2  of a second portable device  500  may be communication pins formed separately from the connection pin T 1 , a pogo pin, or a power line. 
     The second portable device  500  may include a communication module  510 , a controller  520 , a power management integrated circuit  530 , a battery  540 , a display  550 , and a memory  560 . The power management integrated circuit  530 , the battery  540 , and the display  550  are the same as described above with reference to  FIG. 2 . 
     The communication module  510  may include a Universal Asynchronous Receiver-Transmitter (UART) modem  511  and a PLC modem  512 . The UART modem  511  may perform UART communication with the first portable device  100 . The PLC modem  512  is the same as the PLC modem  53  illustrated in  FIG. 9 . 
     The controller  520  may perform all of the operations of the controller  220  illustrated in  FIG. 2 . The controller  520  may control the communication module  510 . For example, the controller  520  may control the UART modem  511  to perform UART communication. The controller  520  may load data stored in a boot code area  561  of the memory  560  and perform a firmware update. The firmware update is the same as described above with reference to  FIGS. 2, 3, and 4 . The controller  520  may load data stored in the user area  562  in a user mode. The controller  520  may control the display  550  to display a charge amount of a battery in the user mode, and control the power management integrated circuit  530  to adjust power supplied from the outside and adjust heat generated in the second portable device  200 . 
     By way of summation and review, it would be advantageous to provide for enhanced data transmission and reception between wireless earphones and a charging case. 
     Embodiments may provide a portable device via which a firmware update may be conducted easily via power line communication (PLC), and an operating method of the portable device. Embodiments may also provide a portable device via which firmware data may be quickly transmitted, and an operating method of the portable device. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.