Mobile device chip and mobile device controlling method therefor

A mobile device chip is provided. The mobile device chip includes a main processor, a multimedia processor, and a direct memory access (DMA) circuit. The multimedia processor is electrically coupled to the main processor. The DMA circuit accesses storage, and the DMA circuit is electrically coupled to the multimedia processor. When the mobile device chip operates in a normal mode, the main processor provides file accessing information of at least part of an audio file stored in the storage to the multimedia processor. When the mobile device chip operates in a power-saving mode, the multimedia processor obtains the data of the at least part of the audio file stored in the storage through the DMA circuit according to the file accessing information provided by the main processor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to the device chip and device controlling method, and more particularly to a mobile device chip and mobile device controlling method.

2. Description of the Related Art

Mobile phones play an important role in people's daily life. For current and next generation of mobile phones, there is a strong demand for reducing the power consumption and making the mobile phones more energy-efficient to maximize operating lifetime under a limited battery power supply.

To reduce the power used in audio playback is one way to reduce the power consumption of the mobile phones. For this purpose, some mobile phones are implemented to have an additional multimedia chip in addition to the mobile device chip, and some mobile phones try to improve their power management without additional multimedia processor.

In regard to the first way, although adding another multimedia chip would reduce the power consumption, the cost of the mobile phone is highly increased. In the second way, system loading, running tasks and running process will be detected to manage clock signals and turn on/off relative hardware. However, the reduced power consumption is very small in the second way and the power wastage is still very considerable because of the basic power overhead. Therefore, how to find an efficient way to reduce the power consumption is an important issue to the mobile phones.

SUMMARY OF THE INVENTION

The invention is directed to a mobile device chip and mobile device controlling method for a mobile device, resulting in reducing the power usage while performing audio playing or audio playback in the mobile device. Therefore, the power consumption is reduced and high energy efficiency is achieved to maximize the operating time under the limited battery power supply for the mobile device.

According to an aspect of the present invention, a mobile device chip is provided. The mobile device chip includes a main processor, a multimedia processor and a direct memory access (DMA) circuit. The multimedia processor is electrically coupled to the main processor. The DMA circuit accesses storage, and the DMA circuit is electrically coupled to the multimedia processor. When the mobile device chip operates in a normal mode, the main processor provides file accessing information of at least part of an audio file stored in the storage to the multimedia processor. When the mobile device chip operates in a power-saving mode, the multimedia processor obtains the data of the at least part of the audio file stored in the storage through the DMA circuit according to the file accessing information provided by the main processor.

According to another aspect of the present invention, a mobile device controlling method is provided. The mobile device controlling method includes the following steps. A mobile device chip comprising a main processor, a multimedia processor, and a direct memory access (DMA) circuit is applied. The multimedia processor is electrically coupled to the main processor, and the DMA circuit accesses storage and is electrically coupled to the multimedia processor. File accessing information of at least part of an audio file stored in the storage is provided to the multimedia processor by the main processor when the mobile device chip operates in a normal mode. The data of the at least part of the audio file stored in the storage is obtained through the DMA circuit according to the file accessing information provided by the main processor by the multimedia processor when the mobile device chip operates in a power-saving mode.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1, a block diagram of a mobile device chip100according to an embodiment of the invention is shown. The mobile device chip100includes a main processor102, a multimedia processor104, and a direct memory access (DMA) circuit106. The multimedia processor104is electrically coupled to the main processor102. The DMA circuit106accesses storage108, and the DMA circuit106is electrically coupled to the multimedia processor104.

When the mobile device chip100operates in a normal mode, the main processor102provides file accessing information of at least part of an audio file stored in the storage108to the multimedia processor104. When the mobile device chip100operates in a power-saving mode, the multimedia processor104obtains the data of the at least part of the audio file stored in the storage108through the DMA circuit106according to the file accessing information provided by the main processor102.

In order to reduce the power consumption, the mobile device chip100operates in the power-saving mode when only audio task is to be served, for example. That is, if only audio task is to be served, the mobile device chip100can operates in the power-saving mode to reduce the power usage while performing audio playing or audio playback in a mobile device. Therefore, the power consumption is reduced and high energy efficiency is achieved to maximize the operating time under the limited battery power supply for the mobile device.

Furthermore, the mobile device chip100can further includes a clock control unit110and a phase locked loop (PLL)112. The clock control unit110controls the PLL112and the clock control unit110is electrically connected to the main processor102and the multimedia processor104.

When the mobile device chip100operates in the normal mode, the PLL112is activated and the clock control unit110provides a first clock signal CLK1and a second clock signal CLK2to the main processor102and the multimedia processor104, respectively, based on a third clock signal CLK3generated by the PLL112. When the mobile device chip100operates in the power-saving mode, the main processor102enters a sleep mode and the PLL112is non-activated, and the clock control unit110provides a fourth clock signal CLK4to the multimedia processor104whose frequency is lower than the frequency of the second clock signal CLK2.

When the mobile device chip100operates in the normal mode, the PLL112generates the third clock signal CLK3according to the reference clock signal CLK0from a clock source114. The frequency of the third clock signal CLK3is usually higher than the frequency of the reference clock signal CLK0. Thus, the frequencies of the first clock signal CLK1and a second clock signal CLK2for the main processor102and the multimedia processor104, respectively, are usually higher than the reference clock signal CLK0. When the mobile device chip100operates in the power-saving mode, the PLL112is non-activated, and the clock control unit110outputs the fourth clock signal CLK4to the multimedia processor104according to the reference clock signal CLK0from the clock source114. Since the main processor102enters the sleep mode, no clock signal is needed for the main processor102.

The main processor102can be implemented by microcontroller unit (MCU), for example, and the multimedia processor104can be implemented by a digital signal processor (DSP). When the mobile device chip100operates in the normal mode, the main processor102handles the operations of communication and user interface of the mobile device116. Usually, the design of the multimedia processor104is simpler than that of the main processor102. When the mobile device chip100operates in the normal mode, the multimedia processor104completes the operation of audio playing or audio playback with the assistance of the main processor102. In some embodiments, the multimedia processor104can also perform the operation of non-audio task if necessary. For example, the main processor102accesses data of an audio file from the storage108and transfers the data to the external memory118. After that, the data of the audio file is transferred from the external memory118to an internal memory310(shown inFIG. 3of the mobile device chip100). The multimedia processor104will read the internal memory310to obtain the data of the audio file to decode the data of the audio file. The decoded data is then outputted to the speaker120for playing.

Besides, when the mobile device chip100operates in the power-saving mode, the multimedia processor104obtains the data of the at least part of the audio file stored in the storage108through the DMA circuit106according to the file accessing information provided by the main processor102before the main processor102enters the sleep mode. With the file accessing information previous obtained from the main processor102before the main processor102enters the sleep mode, the multimedia processor104can obtains the data of the audio file from the storage108through the DMA circuit106without the assistance of the main processor102. The operation of audio playing or audio playback can be performed by the multimedia processor104only, and the clock signal of low frequency is enough for the multimedia processor104to perform audio playing or audio playback. Therefore, the clock signal CLK4with lower frequency is provided to the multimedia processor104instead of the clock signal CLK2when the mobile device chip100operates in the power-saving mode, which can efficiently reduce the power consumption of the mobile device116.

Referring toFIG. 2, the frequency Freq1of the clock signal inputted to the main processor102and the frequency Freq2of the clock signal inputted to the multimedia processor104when the mobile device chip100operates in the normal mode and the power-saving mode is shown. During time periods T1and T3, for example, the mobile device chip100operates in the normal mode; the main processor102receives the first clock signal CLK1whose frequency is f1, while the multimedia processor104receives the second clock signal CLK2whose frequency is f2. The PLL112is activated during time periods T1and T3. During time periods T2and T4, for example, the mobile device chip100operates in the power-saving mode, the main processor102enters sleep mode and no clock signal is needed, while the multimedia processor104receives the fourth clock signal CLK4whose frequency is f4, which is lower than the frequency f2of the second clock signal CLK2. The PLL112is non-activated during time periods T2and T4. Because the main processor102is in sleep mode, the PLL112is non-activated, and the frequency of clock signal needed for the multimedia processor104is lowered, the power consumption is considerably reduced during time periods T2and T4when the mobile device chip100operates in the power-saving mode.

The file accessing information provided by the main processor102includes a physical sector table (PST), for example, which carries a number of PST entries, each PST entry catalogs the physical address of one block data in the storage. When the amount of PST entries is below a first threshold and when the mobile device chip100operates in the power-saving mode, the multimedia processor104will wake up the main processor102and the mobile device chip100is changed to operate in the normal mode to make the main processor102provide the file accessing information to the multimedia processor104again. The threshold can be, for example, one-tenth of total amount of PST entries. The threshold can also be set to other value according to the speed in which the main processor102generates a new PST entry and the speed in which the main processor102transfers the PST entries to the multimedia processor104.

Referring toFIG. 3, an example of the main processor102and the multimedia processor104is shown. The main processor102includes a storage driver302and an audio driver304. The storage driver302manages the storage108. The audio driver304manages audio playing tasks or audio playback tasks in the main processor102when the mobile device chip100operates in the normal mode. The audio driver304further detects if any non-audio tasks use the storage driver302. If no, the audio driver304gets the file accessing information from the storage driver302, transfers the file accessing information to the multimedia processor104, and informs the sleep controller309. The sleep controller309checks if only audio task is operated. If yes, the sleep controller309sets the mobile device chip100to the power-saving mode.

The multimedia processor104includes a storage driver306and an audio decoder308, for example. The storage driver306is responsible to read operation of the storage108when the mobile device chip100is in the power-saving mode. The audio decoder308decodes data from the audio driver304when the mobile device chip100is in the normal mode. The audio decoder308decodes data from the storage driver306when the mobile device chip100is in the power-saving mode. The decoded data is outputted from the audio decoder308to the speaker120for playing. In one example, the storage driver306is a simplified storage driver which is only responsible to read operation of the storage108when the mobile device chip100is in the power-saving mode.

The mobile device chip100can further includes an internal memory310. The storage driver306reads the storage108according to the file accessing information and stores the read data from the storage108into the internal memory310, and the audio decoder308decodes the data stored in the internal memory310. When the data stored in the internal memory310is blow a second threshold, the storage driver306reads the storage108again according to the file accessing information and stores the read data to the internal memory310again. The second threshold, for example, corresponds to the amount of audio data which is double of the amount of audio data decoded by the audio decoder308per time unit, or corresponds to the amount of decoded data for the speaker120to play for a particular time period, for example, 50 milliseconds.

Referring toFIG. 4, the flow chart of the mobile device controlling method when only audio task is performed according to an embodiment of the invention is shown. In step420, the audio driver304enables the clock control unit110. Then, in step422, the audio driver304starts audio playback. In step402, the audio driver304prepares audio data, the storage driver302prepares the file accessing information (for example, PST), and the audio driver304transfers the file accessing information to the multimedia processor104. After that, steps404and408are entered. In step404, the main processor102enters the sleep mode, and then the PLL112is non-activated (for example, powered off) and no clock signal is inputted to the main processor102in step406.

In step408, it is determined that whether the audio data stored in the internal memory310for audio playing or audio playback is enough. If not, step410is performed; if yes, step412is performed. In step410, the storage driver306uses the file accessing information (for example, the PST entries of PST) to get more audio data from the storage108through the DMA circuit106, and stores the audio data in the internal memory310. In step412, the audio decoder308reads the audio data in the internal memory310and decodes the audio data. For example, the audio data is decoded to a pulse-code modulation (PCM) data. After that, the decoded data is outputted to the speaker120in step414, followed by step416, in which it is determined that whether the file accessing information (for example, the PST entries) is enough. If yes, step408is repeated; if not, step418is performed to wake up the main processor102, and then step424is performed so that the PLL112is activated. After that, step402is performed again to get more file accessing information (for example, get more PST entries). In the flow chart ofFIG. 4, steps402,404,406,420,422, and424are performed by the main processor102, and steps408,410,412,414, and416are performed by the multimedia processor104.

Referring toFIG. 5, the flow chart of the mobile device controlling method when non-audio task is performed according to an embodiment of the invention is shown. As shown in step502, when there is a non-audio task to be performed, the main processor102is waked up. After that, as shown in step503, the PLL112is also activated. Then, the main processor102serves the non-audio task in step506. After the non-audio task is finished, the main processor102enters the sleep mode in step508, and the PLL112is non-activated in step510.

After step503, step516is also performed by the main processor102. The main processor102prepares the audio data and the file accessing information (for example, the PST) to the multimedia processor104so that the multimedia processor104can decode the audio data or obtain more audio data from the storage108when the main processor102is in the sleep mode to reduce the power consumption.

Referring toFIG. 6andFIG. 7,FIG. 6shows an example of the sections of storage108which stores the audio data of the audio file, andFIG. 7shows an example of PST. Assume that sectors1,2,3,10,11, and310-316of the storage108stores the audio data of at least part of the audio file which is going to be played or playback. The storage driver302gets the sector index for the audio data of the audio file (as shown in the column “Sector Index” inFIG. 7), and the storage driver302generates the PST accordingly (as shown in the column “PST” inFIG. 7). The PST is then transferred to the multimedia processor104for reading audio data from the storage108through the DMA circuit106.

The mobile device chip100of the embodiment is implemented for mobile communication devices, for example, mobile phones, personal digital assistants (PDA), tablets, handheld computers, handheld game consoles, and so on. The storage driver302, the audio driver304, the storage driver306, and the audio decoder308can be implemented by hardware or software. In this embodiment of the invention, with the use of the DMA circuit106and the file accessing information (for example, PST), audio data in the storage108can be accessed by the multimedia processor104and put in the internal memory310directly to be decoded by the multimedia processor104. When audio playing or audio playback, the main processor102can enter sleep mode, the external memory118can be powered down, the PLL112can be non-activated, and the frequency of the clock signal for the multi-media processor104can be reduced to the working clock frequency of the audio decoder308. Comparing to the conventional mobile devices which are implemented to have a separated multimedia chip in addition to the mobile device chip, it is not necessary to have an additional and separated multimedia chip for this embodiment of the invention, which reduces the cost of the mobile device. Therefore, in this embodiment of the invention, the power usage while performing audio playing or audio playback in the mobile device of this embodiment is lowered, the power consumption is reduced, and high energy efficiency is achieved to maximize the operating time under the limited battery power supply for the mobile device with low cost.