Data transmission systems and methods

A data transmission system and method are provided. The data transmission system includes a first link partner and an optical transceiver unit. The first link partner includes a controller. When the first link partner is in an abnormal operation mode, the controller controls the first link partner to exit from the abnormal operation mode. The optical transceiver unit is coupled between the first link partner and a second link partner and performs data transmission between the first link partner and the second link partner. According to the data transmission system and method, one link partner can accurately detect whether another link partner is coupled to the one link partner through an optical transceiver unit. Accordingly, data transmission between the two link partners can be stably performed through the optical transceiver unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of China application Serial No. 201010221271.1 filed Jul. 8, 2010, the subject matter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a data transmission system and method, and more particularly to a data transmission system and method for accurately detecting a terminal apparatus.

2. Description of the Related Art

As optical transmission techniques develop, optical transmission techniques have been applied more widely as optical fiber transmission has transmission rate/transmission distance benefits and anti-interference capabilities. Due to optical transmission technique advantages, more applications are coupling a host and a device respectively to optical transceiver modules to perform opto-electronic conversion and then perform data transmission through an optical fiber. However, there are some problems occurring in the above applications. It is desired to provide a data transmission system and method for one link partner to accurately detect whether another link partner is coupled to the one link partner through an optical transceiver unit. For such a system and method, the data transmission between the two link partners (such as a host and a device) would be stably performed through the optical transceiver unit, which would solve the problems found in current optical transmission techniques.

BRIEF SUMMARY OF THE INVENTION

An exemplary embodiment of a data transmission system includes a first link partner and an optical transceiver unit. The first link partner includes a controller. When the first link partner is in an abnormal operation mode, the controller controls the first link partner to exit from the abnormal operation mode. The optical transceiver unit is coupled between the first link partner and a second link partner and performs data transmission between the first link partner and the second link partner.

An exemplary embodiment of a data transmission method for a data transmission system is provided. The data transmission system includes a first link partner, a second link partner, and an optical transceiver unit coupled between the first link partner and the second link partner. The data transmission method includes the steps of: determining whether a predetermined condition has been satisfied when the first link partner is in an abnormal operation mode; and controlling the first link partner to exit from the abnormal operation mode when the predetermined condition has been satisfied.

According to the data transmission system and the data transmission method, a link partner can accurately detect whether another link partner is coupled to the link partner through an optical transceiver unit. Accordingly, data transmission between the two link partners can be stably performed through the optical transceiver unit.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a block diagram showing data transmission between a host and a device. InFIG. 1, a host120may be a high-speed electronic transceiver which has a PCI-e (peripheral controller interface-express) interface specification or a USB 3.0 interface specification and supports a hot plugging function. The host120performs polling in a predetermined time period to detect whether a device has been inserted. When the host120detects that a device150has been inserted, the host120issues a link training sequence to build a link to the device150. At the same time, the device150also performs polling to detect whether a host is present. When the device150detects that the host120is present, the device150also issues a link training sequence to build a link to the host120.

The connection between the host120and the device150is shown inFIG. 1. A positive transmitting signal terminal TX+ and a negative transmitting signal terminal TX− of the host120are coupled to a positive receiving signal terminal RX+ and a negative receiving signal terminal RX− of the device150, respectively, so that data may be sent from the host120to the device150. The data sent from the host120to the device150can be sent in a form of a differential signal pair. A positive receiving signal terminal RX+ and a negative receiving signal terminal RX− of the host120are coupled to a positive transmitting signal terminal TX+ and a negative transmitting signal terminal TX− of the device150, respectively, so that data may be sent from the device150to the host120. The data sent from the device150to the host120can be sent in a form of a differential signal pair. The host120performs polling to detect whether there is a differential terminator impedance coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the host120to determine whether a device has been inserted according to the detection result. When the device150is coupled to the host120as shown inFIG. 1and ready for data transmission, a differential terminator impedance112is coupled between the positive receiving signal terminal RX+ and the negative receiving signal terminal RX− of the device150. In one embodiment, each of the positive receiving signal terminal RX+ and the negative receiving signal terminal RX− of the device150is coupled to a ground through a resistor to form the differential terminator impedance112. The host120detects that there is a differential terminator impedance, which is the differential terminator impedance112, coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the host120, and determines that the device150has been inserted. The host120then issues a link training sequence to build a link to the device150. Also, the device150performs polling to detect whether there is a differential terminator impedance113coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the device150to determine whether the device150is coupled to the host120. In one embodiment, each of the positive receiving signal terminal RX+ and the negative receiving signal terminal RX− of the host120is coupled to a ground through a resistor to form the differential terminator impedance113. When the device150detects there is a differential terminator impedance113coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the device150, the device150issues a response signal to the host120. When the host120receives the response signal, the link training sequence has been built successfully, and the link between the host120and the device150is performed normally to perform data transmission. In one embodiment, the response signal is a low frequency periodic signal (LFPS) with a period range of 20˜100 ns.

In certain applications, for example, when a host and a device are coupled to optical transceiver modules respectively to perform opto-electronic conversion and then data transmission between the host and the device is performed through an optical fiber, there are some problems, which will be described in the following.FIG. 2is a block diagram showing data transmission between a host and a device through an optical transceiver unit. In one embodiment, the optical transceiver unit is an active optical cable (AOC). As shown inFIG. 2, an optical transceiver unit230includes an optical transceiver module201, an optical transceiver module203, and an optical fiber205. For clear drawings and convenient description,FIG. 2only shows electrical connection of data transmission between a host210and a device250, but optical passive components in the host210and the device250, such as laser diodes and photo-detect diodes are omitted. The optical passive components are used for the conversions between electronic signals and optical signals.

InFIG. 2, a positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the host210are coupled to a first transmitting pair T+/T− of the optical transceiver module201. The optical transceiver module201is coupled to the host210to convert an electronic signal issued by the host210to an optical signal. The optical fiber205is coupled between the two optical transceiver modules201and203to perform optical transmission therebetween. The optical transceiver module203is coupled to the device250to convert an optical signal to an electronic signal, and the electronic signal is provided to a positive receiving signal terminal RX+ and a negative receiving signal terminal RX− of the device250through a second receiving pair R+/R− of the optical transceiver module203for data transmission.

When one terminal of the optical transceiver unit230(the terminal close to the optical transceiver module201) is coupled to the host210, since the optical transceiver module201includes internal fixed resistors207and209which are coupled to the first transmitting pair T+/T− of the optical transceiver module201, the host210detects that there is a differential terminator impedance coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the host210to determine that a device has been inserted. Thus, the host210issues a link training sequence. However, when the other terminal of the optical transceiver unit230has been not coupled to the device250, the link training sequence is built unsuccessfully, and the host210enters an abnormal operation mode. In the abnormal operation mode, the host210can not perform data transmission with the device250any more and also not exit from the abnormal operation mode. Only after the host210is reset, will the host210be able to determine whether a device has been coupled to the host210again. In one embodiment, the abnormal operation mode is a compliance mode in which the completeness of the signal issued by the host210is examined.

Moreover, as shown inFIG. 2, the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the device150are coupled to a second transmitting pair T+/T− of the optical transceiver module203. The optical transceiver module203is coupled to the device250to convert an electronic signal issued by the device250to an optical signal. An optical fiber206is coupled between the two optical transceiver modules201and203to perform optical transmission therebetween. The optical transceiver module201is coupled to the host210to convert an optical signal to an electronic signal, and the electronic signal is provided to a positive receiving signal terminal RX+ and a negative receiving signal terminal RX− of the host210through a first receiving pair R+/R− of the optical transceiver module201for data transmission.

When one terminal of the optical transceiver unit230(the terminal close to the optical transceiver module203) is coupled to the device250, since the optical transceiver module203includes internal fixed resistors211and213which are coupled to the second transmitting pair T+/T− of the optical transceiver module203, the device250detects that there is a differential terminator impedance coupled between the positive transmitting signal terminal TX+ and the negative transmitting signal terminal TX− of the device250to determine that a host has been inserted. Thus, the device250issues a link training sequence. However, when the other terminal of the optical transceiver unit230is not coupled to the host210, the link training sequence is built unsuccessfully, and the device250enters an abnormal operation mode. In one embodiment, the abnormal operation mode is a compliance mode in which the completeness of the signal issued by the device250is examined In another embodiment, the abnormal operation mode is a testing mode in which the completeness of the signal issued by a link partner is examined. In another embodiment, the internal fixed resistors211and213exist at the second transmitting pair T+/T− of the optical transceiver module203, and each of the internal fixed resistors211and213is coupled between one of the second transmitting pair T+/T− and a ground, respectively. When the host210or the device250enters a compliance mode, data transmission between the host210and the device250can not be performed. Thus, one link partner can not accurately determine whether another link partner is coupled to the one link partner through an optical transceiver unit, and, as a result, data transmission between the two link partners (such as a host and a device) can not be stably performed through the optical transceiver unit to build the optical fiber communication. Thus, it is desired to provide a new data transmission system and method which solves the above problems.

According to the invention, when a host or a device is coupled to an optical transceiver unit, if the host or the device enters an abnormal operation mode, the host or the device can be controlled to exit from the abnormal operation mode by a controller within in the host or the device. Accordingly, when both of a host and a device are coupled to an optical transceiver unit and ready for data transmission, normal data transmission is performed between the host and the device. In an embodiment, a host or a device exits from the abnormal operation mode and returns to a link detection state (for example, Rx.Detect state in the USB standard) or a response signal polling state (for example, polling.LFPS state in the USB standard) of the host or the device through the controlling of a controller within the host or the device to detect whether the host or the device is coupled to another device or another host or whether another device or another host has issued a response signal. The above host and device can be implemented as a host and device with a serial transmission interface specification, such as a PCI-e (peripheral controller interface-express) interface specification or a USB 3.0 interface specification, which perform optical fiber transmission through an optical transceiver unit.

FIG. 3is a flow chart of one exemplary embodiment of a data transmission between a first link partner and a second link partner (such as between a host and a device). InFIG. 3, an embodiment is described, wherein, a first link partner (such as a host) performs polling to detect whether a second link partner (such as a device) has be inserted. The steps of the second link partner (such as a device) performing polling to detect whether the first link partner (such as a host) has be inserted is the same as that of the steps ofFIG. 3; thus, description thereof is omitted here.

In the step301, the first link partner is in a link detection state (such as Rx.detect state). When the first link partner is coupled to one terminal of the optical transceiver unit, since the optical transceiver modules at the two terminals of the optical transceiver unit230have internal fixed resistors, the first link partner detects that a differential terminator impedance is present. When the first link partner detects that a differential terminator impedance is present, the first link partner issues a link training sequence. At this time, the first link partner enters into a response signal polling state. The flow proceeds to step303.

In the step303, the first link partner performs polling to detect whether the first link partner has received a response signal issued by the second link partner in a first predetermined time. During the first predetermined time, the first link partner is in the response signal polling state. In an embodiment, the first link partner performs polling to detect whether the first link partner has received a low-frequency periodic signal issued by the second link partner in the first predetermined time, and, during the first predetermined time, the first link partner is in a low-frequency periodic signal polling state (Polling.LFPS state). If the first link partner has received a low-frequency periodic signal issued by the second link partner, the flow proceeds to step305; if the first link partner has not received a low-frequency periodic signal issued by the second link partner, the flow proceeds to step307. In the embodiment, the first link partner includes a first timer which is initiated when the first link partner enters into the response signal polling state to perform a clocking operation to detect whether the first predetermined time has been exceeded. Similarly, the second link partner also includes a first timer which is initiated when the second link partner enters into the response signal polling state to perform a clocking operation to detect whether the first predetermined time has been exceeded. In an embodiment, the first timers are implemented in link layers of controllers of the first link partner and the second link partner, respectively. When the first timers detect that the first predetermined time has been exceeded, then step305or307is performed. Then, the first link partner and the second link partner reset the first timers (that is the clocking result of the clock operation is cleared) to re-perform the clocking operation.

In the step305, when both of the first link partner and the second link partner are coupled to the two optical transceiver modules of the optical transceiver unit respectively, the first link partner detects the response signal issued by the second link partner, and the link training sequence has been built successfully. Thus, the data transmission between the first link partner and the second link partner is performed.

In the step307, when the first link partner does not detect the response issued by the second link partner in the first predetermined time, the link training sequence has not been built successfully, and the first link partner enters an abnormal operation mode. In an embodiment, the abnormal operation mode is a compliance mode. In the abnormal operation mode, data transmission can not be performed between the first link partner and the second link partner. The flow proceeds to Step309.

In the step309, in the abnormal operation mode, the first link partner performs polling to detect whether the first link partner has received a response signal issued by the second link partner. If the first link partner has received a response signal issued by the second link partner, the flow proceeds to step301. If the first link partner has not received a response signal issued by the second link partner, the flow proceeds to step307. In the embodiment, the first link partner includes a detection circuit which is initiated when the first link partner enters the abnormal operation mode to detect whether the first link partner has received a response signal issued by the second link partner. Similarly, the second link partner also includes a detection circuit which is initiated when the second link partner enters the abnormal operation mode to detect whether the second link partner has received a response signal issued by the first link partner. In an embodiment, the detection circuits are implemented in link layers of controllers of the first link partner and the second link partner, respectively. When the detection circuit detects that the first link partner has not received a response signal issued by the second link partner, or specifically, the second link partner has not been inserted or the second link partner is not ready for data transmission, the flow proceeds to step307, and the first link partner stays in the abnormal operation mode. When the detection circuit detects that the first link partner has received a response signal issued by the second link partner, or specifically, the second link partner has been inserted, the first link partner exits from the abnormal operation mode. Then, the flow returns to step301.

After step301is performed, when the first link partner and the second link partner are coupled to the optical transceiver modules, the link training sequence has been built successfully. Thus, steps303and305are then performed to perform normal data transmission between the first link partner and the second link partner.

FIG. 4is a flow chart of another exemplary embodiment of a data transmission between a first link partner and a second link partner (such as between a host and a device). InFIG. 4, an embodiment is described in that a first link partner (such as a host) performs polling to detect whether a second link partner (such as a device) has be inserted.

In the embodiment ofFIG. 4, the steps401,403,405, and407are the same as the steps301,303,305, and307of the embodiment ofFIG. 3; thus, the descriptions thereof are omitted here.

In the step409, in the abnormal operation mode, it is detected whether a second predetermined time has been exceeded. If the second predetermined time has been exceeded, the flow returns to step401. If the second predetermined time has not been exceeded, the flow returns to step407. In the embodiment, the first link partner includes a second timer which is initiated when the first link partner enters into the response signal polling state to perform a clocking operation to detect whether the second predetermined time has been exceeded. Similarly, the second link partner also includes a second timer which is initiated when the second link partner is in the response signal polling state to perform a clocking operation to detect whether the second predetermined time has been exceeded. In an embodiment, the second timers are implemented in link layers of controllers of the first link partner and the second link partner, respectively. When the second timer detects that the second predetermined time has exceed, the first link partner exits from the abnormal operation mode. In the embodiment, when step401is performed, the first link partner returns to the link detection state and resets the second timer (that is, the clocking result of the clock operation is cleared).

When the second timer performs the clocking operation to detect that the second predetermined time has not been exceeded, the first link partner stays in the abnormal operation mode in step407.

After step401is performed, when the first link partner and the second link partner are coupled to the optical transceiver modules, the link training sequence has been built successfully. Steps403and405are then performed to perform normal data transmission between the first link partner and the second link partner.

FIG. 5is a flow chart of another exemplary embodiment of a data transmission between a first link partner and a second link partner. In the embodiment ofFIG. 5, the steps501,503,505, and507are the same as the steps301,303,305, and307of the embodiment ofFIG. 3; thus, descriptions thereof are omitted here.

In the step509, in the abnormal operation modes, the first link partner performs polling to detect whether the first link partner has received a response signal issued by the second link partner. If the first link partner has received a response signal issued by the second link partner, the flow returns to step503. If the first link partner has not received a response signal issued by the second link partner, the flow returns to step507. When a detection circuit of the first link partner detects that the first link partner has not received a response signal issued by the second link partner, or specifically, the second link partner has not been inserted or the second link partner or the second link partner is not ready for data transmission, step507is performed, and the first link partner stays in the abnormal operation mode. When the detection circuit detects that the first link partner has received a response signal issued by the second link partner, or specifically, the second link partner has been inserted, the first link partner exits from the abnormal operation mode. Then, in the embodiment ofFIG. 5, step503is performed.

After step503is performed, when the first link partner and the second link partner are coupled to the optical transceiver modules, the link training sequence has been built successfully since the first link partner has received a response signal issued by the second link partner. Step505is then performed to perform normal data transmission between the first link partner and the second link partner.

FIG. 6is a flow chart of another exemplary embodiment of a data transmission between a first link partner and a second link partner. In the embodiment ofFIG. 6, the steps601,603,605, and607are the same as the steps401,403,405, and407of the embodiment ofFIG. 4; thus, descriptions thereof are omitted here.

In the step609, in the abnormal operation mode, it is detected whether a second predetermined time has been exceeded. If the second predetermined time has been exceeded, the flow returns to step603. If the second predetermined time has not been exceeded, the flow returns to step607. When the second timer performs the clocking operation to detect that the second predetermined time has been exceeded, the first link partner exits from the abnormal operation mode. In the embodiment, when step603is performed., the first link partner then returns to the response signal polling state and resets the second timer (that is, the clocking result of the clock operation is cleared) to re-clock the second predetermined time.

When the second timer performs the clocking operation to detect that the second predetermined time has not been exceeded, the first link partner stays in the abnormal operation mode in step607.

After step603is performed, when the first link partner and the second link partner are coupled to the optical transceiver modules, the link training sequence has been built successfully since the first link partner has received a response signal issued by the second link partner. Next, step605is performed to perform normal data transmission between the first link partner and the second link partner.

FIGS. 3-6show four exemplary embodiments. In these embodiments, when a host or a device is coupled to an optical transceiver unit, if the host or the device enters an abnormal operation mode, the host or the device can be controlled to exit from the abnormal operation mode by a controller within in the host or the device. In an embodiment, a host or a device exits from the abnormal operation mode and returns to a link detection state or a response signal polling state of the host or the device through controlling of a controller within the host or the device to detect whether the host or the device is coupled to another device or another host or whether another device or another host issues a response signal. Accordingly, when both of a host and a device are coupled to an optical transceiver unit and ready for data transmission, normal data transmission is performed between the host and the device.