With the rapid development of information technology, mobile devices such as mobile phones, PDA, handhelds and other products are more and more widely used. Coupled with the current mobile devices increasing processor performance continues to increase, wireless applications, advanced graphics and more. Features on the increase, resulting in increasing power consumption in a mobile terminal products; therefore, gave higher performance requirements on battery, particularly in terms of battery management, including power management and battery monitoring battery, which is embedded in the product development issues that you must consider.

2. the introduction of battery-management chip

2.1. battery charge management IC bq24032A

Bq24032A supports USB charging and charging AC battery management chip. By bq24032A the battery is charging. This chip provides a power output of the system as a whole. Battery management IC bq24032A VBAT battery monitoring chip bq26220 VBAT PIN. PSEL selected for the power port, can be used to  Nikon Coolpix P300 Battery Charger select the input power as the primary input power supply (USB or AC). If the main power supply is not available, the system automatically enter the second power supply, battery input as a last option, when a USB or AC power only if it does not choose to use a battery as a power source. PSEL is set to low, USB is selected as the primary input [1]. Figure 1 below for the battery management IC bq24032A and its peripheral circuit diagram:

Battery management IC bq24032A and its peripheral circuit diagram

2.2. battery monitoring IC bq26220

Bq26220 is an advanced battery monitoring module, it can be accurately measured the charge and discharge current, and supports all the necessary functions to manage battery capacity, the chip can be used for hand phone, PDA, and other portable devices. Execute with bq26220 chip and controller battery management function, main controller responsible for the data delivery to the end user of bq26220 power management system and receives the data. This module provides a general Flash for 64 bit, 8-bit ID of ROM, and 32 bit RAM storage space. These non-volatile storage space to save monitoring information or critical battery battery parameters.

Where BAT for battery voltage detection input ports, this PIN is used to detect and measure the voltage of the battery. HDQ one-way HDQ interface, is a single serial communication interface, it is bi-directional inputs, is responsible for passing information to the main controller of the register, in the information to register and receive the main controller, battery monitoring chip bq26220 HDQ PXA272 processor-port GPIO119 port [2]. Principles of Figure 2 below for bq26220 chip module:

2 x principle of chip module

3. battery-powered model and driver initialization

Samples are included in the Windows CE device drivers are divided into two types: single-chip driver (Monolithic device driver) and layered drivers (Layered Device driver). Tiered model of development can reduce development difficulties, shortened development cycles, use hierarchy in a battery-driven development-driven development model.

Layered driver is made up of two separate layers: the top is the model device driver (MDD), the lower is platform-dependent driver (PDD). Server provided by the device driver interface (DDSI) is the set of functions implemented in the PDD, and MDD calls. Because Microsoft provides the MDD and all source  Panasonic Lumix DMC-ZS1 Battery Charger code related to the module, so this part do not have to make any changes, simply their PDD module with MDD module chain to form a public library [3]. MDD IoCTLS call specific functions to access hardware in the PDD's specific characteristics.

Windows CE battery-driven requirements of MDD function include:

Init、Deinit、Open、Close、Read、Write、Seek、PowerDown、PowerUp、IOControl。

Windows CE battery-driven requirements of PDD functions include:

BatteryPDDInitialize、BatteryPDDDeinitialize、BatteryPDDGetStatus、BatteryPDDGetLevels、BatteryPDDSupportsChangeNotification、BatteryPDDPowerHandler、 BatteryPDDResume。

Battery drive initialization

After successful post on the system, the upper battery-powered entry point function is called, a battery-driven initialization:

(1) determine whether the event has been interrupted initialization, if there is no initialization, you perform one of the following operations, if you have conducted an initialized, the close event handle.

(2) initial battery of global variables.

(3) if the interrupt event is successful, ResumeThreadProc is called to create the battery thread. Thread in the called function, set the battery thread priority level, and then in a loop waiting for the interrupt event.

(4) the PDD layer is called the initialization function BatteryPDDInitialize; in the PDD layer, for the GPIO register and power management registers allow two virtual memory.

(5) that initiated the AC97 registers.

(6) initializes the ring buffer storage battery.

(7) call BatteryAPIGetSystemPowerStatusEx2 function updates data in a structure PSYSTEM-battery POWERSTATUS_EX2.

4. the BatteryAPIGetSystemPowerStatusEx function

Main BatteryAPIGetSystemPowerStatusEx function gets system power state value. During execution is done by calling the BatteryAPIGetSystemPowerStatusEx2 function. While the BatteryAPIGetSystemPowerStatusEx2 function calls the BatteryPDDGetStatus function to get the battery status information, by calling the BatteryPDDGetStatus function GetMainBatteryVoltage Gets the main battery voltage value, allowing you to call GetPowerDevStatus for battery device status, and gets the remaining capacity of the scale value. Figure 3 BatteryAPIGetSystemPowerStatusEx function call graphs:

BatteryAPIGetSystemPowerStatusEx function call graphs

5. get battery voltage values CalcMainBatteryVoltage

Bq26220 BAT port detection on battery power, and register through BATH-BATL pass to the upper deck. The BATH (bits to address =0x72--No. 0 2nd bit) and BATL low-bit registers (address =0x71--No. 0 bits to the 7th bits) contains the battery voltage after ADC conversion result. The voltage to 11 bits, 2.44mV step, and binary forms of expression with the LSB. BATH register 3rd LSB bit No. 0 bits representing the MSB,BATL representative. 5 v Max voltage measurement range.

3rd BATH register bit to the 7th bit offset information stored voltage after the ADC, the most important bit of information is in the 4-bit (the 3rd bit to the 7th bit) offset data tag bit.

LSB gets modified, in μv units, master controller is responsible for the pass LSB after obtaining correction factor and offset measurement ADC voltage value. Here is the formula:

Correct =VBATx (2.44+LSB-modified)-offset

Calculation examples are as follows:

For example: If the real LSB=+2.45mV, offset =+80mV

Calculate the correct VBAT:

LSB-modified =+10 mu V=0.001 mV

Offset =+10x8mV=80 mV

Correct =VBATx (2.44+0.01)-80

Program implementation process is as follows in Figure 4:

CalcMainBatteryVoltage function flow chart

6. battery charge calculation method

Percentage is the voltage of the battery percentage display. Hardware testing found that the battery power and the battery voltage is not a simple linear relationship, you need to partition to convert percentage correction between. At room temperature, battery voltage and power curve of our equipment is as follows (Figure 5):

The diagram in Figure 5 the battery voltage and power

Drivers create a ring buffer of 16 characters length, sampling points increased to 16, which can increase the reliability of the results of the sampling. Battery voltage sampling even_samp 16 sample values and to remove a minimum and a maximum value, and then averaged.

In our mobile devices, the maximum voltage of the battery as 559 (4.10V), the minimum voltage is 455 (3.30V), with two dotted lines in Figure 5 as the boundary of the range, can be divided into 4.10V~3.80V,3.80V~3.60V,3.60V~3.30V these three bands, the battery voltage values for partition processing, three intervals on the slope of the curve approximation:

4.1V～3.80V：Kl=（100－70）／（4.10－3.80）

3.80V～3.60V：K2=（70－20）／（3.80—3.60）

3.60V～3.30V：K3=20／（3.60－3.30）

4.10V～3.30V：K=100／（4.10－3.30）

When the battery charge percentage conversion, when we get in the 559~455 range of sample values, first obtain a percentage of the original value voltage_percent= (even_samp-455) *l00/(559-455). And then make appropriate adjustments for different intervals, percentage of power are respectively:

4.10V～3.80V：voltage_ercent+=（4.10－even_samp * 7.5/1024）×（K－K1）

3.80V～3.60V：voltage_percent+=（3.80－even_samp * 7.5/1024）×（K－K2）

3.60V～3.30V：voltage_percent－=（even_samp－3.30V * 7.5/1024）×（K－K3）

Through the interval of more than three separate treatment, so that you get the correct battery [4].

This article describes the Windows CE system, battery-based power management IC bq24032A and battery bq26220 battery monitoring chip-driven implementation. Focuses on the calculation method of battery and battery voltage gets. Battery management provided a good reference.Design of battery management and monitoring

With the rapid development of information technology, mobile devices such as mobile phones, PDA, handhelds and other products are more and more widely used. Coupled with the current mobile devices increasing processor performance continues to increase, wireless applications, advanced graphics and JVC GR-D375U Battery Charger more. Features on the increase, resulting in increasing power consumption in a mobile terminal products; therefore, gave higher performance requirements on battery, particularly in terms of battery management, including power management and battery monitoring battery, which is embedded in the product development issues that you must consider.

2. the introduction of battery-management chip

2.1. battery charge management IC bq24032A

Bq24032A supports USB charging and charging AC battery management chip. By bq24032A the battery is charging. This chip provides a power output of the system as a whole. Battery management IC bq24032A VBAT battery monitoring chip bq26220 VBAT PIN. PSEL selected for the power port, can be used to select the input power as the primary input power supply (USB or AC). If the main power supply is not available, the system automatically enter the second power supply, battery input as a last option, when a USB or AC power only if it does not choose to use a battery as a power source. PSEL is set to low, USB is selected as the primary input [1]. Figure 1 below for the battery management IC bq24032A and its peripheral circuit diagram:

Battery management IC bq24032A and its peripheral circuit diagram

2.2. battery monitoring IC bq26220

Bq26220 is an advanced battery monitoring module, it can be accurately measured the charge and discharge current, and supports all the necessary functions to manage battery capacity, the chip can be used for hand phone, PDA, and other portable devices. Execute with bq26220 chip and controller battery management function, main controller responsible for the data delivery to the end user of bq26220 power management system and receives the data. This module provides a general Flash for 64 bit, 8-bit ID of ROM, and 32 bit RAM storage space. These non-volatile storage space to save monitoring information or critical battery battery parameters.

Where BAT for battery voltage detection input ports, this PIN is used to detect and measure the voltage of the battery. HDQ one-way HDQ interface, is a single serial communication interface, it is bi-directional inputs, is responsible for passing information to the main controller of the register, in the information to register and receive the main controller, battery monitoring chip bq26220 HDQ PXA272 processor-port GPIO119 port [2]. Principles of Figure 2 below for bq26220 chip module:

2 x principle of chip module

3. battery-powered model and driver initialization

Samples are included in the Windows CE device drivers are divided into two types: single-chip driver (Monolithic device driver) and layered drivers (Layered Device driver). Tiered model of development can reduce development difficulties, shortened development cycles, use hierarchy in a battery-driven development-driven development model.

Layered driver is made up of two separate layers: the top is the model device driver (MDD), the lower is platform-dependent driver (PDD). Server provided by the device driver interface (DDSI) is the set of functions implemented in the PDD, and MDD calls. Because Microsoft provides the MDD and all source code related to the module, so this part do not have to make any changes, simply their PDD module with MDD module chain to form a public library [3]. MDD IoCTLS call specific functions to access hardware in the PDD's specific characteristics.

Windows CE battery-driven requirements of MDD function include:

Init、Deinit、Open、Close、Read、Write、Seek、PowerDown、PowerUp、IOControl。

Windows CE battery-driven requirements of PDD functions include:

BatteryPDDInitialize、BatteryPDDDeinitialize、BatteryPDDGetStatus、BatteryPDDGetLevels、BatteryPDDSupportsChangeNotification、BatteryPDDPowerHandler、 BatteryPDDResume。

Battery drive initialization

After successful post on the system, the upper battery-powered entry point function is called, a battery-driven initialization:

(1) determine whether the event has been interrupted initialization, if there is no initialization, you perform one of the following operations, if you have conducted an initialized, the close event handle.

(2) initial battery of global variables.

(3) if the interrupt event is successful, ResumeThreadProc is called to create the battery thread. Thread in the called function, set the battery thread priority level, and then in a loop waiting for the interrupt event.

(4) the PDD layer is called the initialization function BatteryPDDInitialize; in the PDD layer, for the GPIO register and power management registers allow two virtual memory.

(5) that initiated the AC97 registers.

(6) initializes the ring buffer storage battery.

(7) call BatteryAPIGetSystemPowerStatusEx2 function updates data in a structure PSYSTEM-battery POWERSTATUS_EX2.

4. the BatteryAPIGetSystemPowerStatusEx function

Main BatteryAPIGetSystemPowerStatusEx function gets system power state value. During execution is done by calling the BatteryAPIGetSystemPowerStatusEx2 function. While the BatteryAPIGetSystemPowerStatusEx2 function calls the BatteryPDDGetStatus function to get the battery status information, by calling the BatteryPDDGetStatus function GetMainBatteryVoltage Gets the main battery voltage value, allowing you to call GetPowerDevStatus for battery device status, and gets the remaining capacity of the scale value. Figure 3 BatteryAPIGetSystemPowerStatusEx function call graphs:

BatteryAPIGetSystemPowerStatusEx function call graphs

5. get battery voltage values CalcMainBatteryVoltage

Bq26220 BAT port detection on battery power, and register through BATH-BATL pass to the upper deck. The BATH (bits to address =0x72--No. 0 2nd bit) and BATL low-bit registers (address =0x71--No. 0 bits to the 7th bits) contains the battery voltage after ADC conversion result. The voltage to 11 bits, 2.44mV step, and binary forms of expression with the LSB. BATH register 3rd LSB bit No. 0 bits representing the MSB,BATL representative. 5 v Max voltage measurement range.

3rd BATH register bit to the 7th bit offset information stored voltage after the ADC, the most important bit of information is in the 4-bit (the 3rd bit to the 7th bit) offset data tag bit.

LSB gets modified, in μv units, master controller is responsible for the pass LSB after obtaining correction factor and offset measurement ADC voltage value. Here is the formula:

Correct =VBATx (2.44+LSB-modified)-offset

Calculation examples are as follows:

For example: If the real LSB=+2.45mV, offset =+80mV

Calculate the correct VBAT:

LSB-modified =+10 mu V=0.001 mV

Offset =+10x8mV=80 mV

Correct =VBATx (2.44+0.01)-80

Program implementation process is as follows in Figure 4:

CalcMainBatteryVoltage function flow chart

6. battery charge calculation method

Percentage is the voltage of the battery percentage display. Hardware testing found that the battery power and the battery voltage is not a simple linear relationship, you need to partition to convert percentage correction between. At room temperature, battery voltage and power curve of our equipment is as follows (Figure 5):

The diagram in Figure 5 the battery voltage and power

Drivers create a ring buffer of 16 characters length, sampling points increased to 16, which can increase the reliability of the results of the sampling. Battery voltage sampling even_samp 16 sample values and to remove a minimum and a maximum value, and then averaged.

In our mobile devices, the maximum voltage of the battery as 559 (4.10V), the minimum voltage is 455 (3.30V), with two dotted lines in Figure 5 as the boundary of the range, can be divided into 4.10V~3.80V,3.80V~3.60V,3.60V~3.30V these three bands, the battery voltage values for partition processing, three intervals on the slope of the curve approximation:

4.1V～3.80V：Kl=（100－70）／（4.10－3.80）

3.80V～3.60V：K2=（70－20）／（3.80—3.60）

3.60V～3.30V：K3=20／（3.60－3.30）

4.10V～3.30V：K=100／（4.10－3.30）

When the battery charge percentage conversion, when we get in the 559~455 range of sample values, first obtain a percentage of the original value voltage_percent= (even_samp-455) *l00/(559-455). And then make appropriate adjustments for different intervals, percentage of power are respectively:

4.10V～3.80V：voltage_ercent+=（4.10－even_samp * 7.5/1024）×（K－K1）

3.80V～3.60V：voltage_percent+=（3.80－even_samp * 7.5/1024）×（K－K2）

3.60V～3.30V：voltage_percent－=（even_samp－3.30V * 7.5/1024）×（K－K3）

Through the interval of more than three separate treatment, so that you get the correct battery [4].

This article describes the Windows CE system, battery-based power management IC bq24032A and battery bq26220 battery monitoring chip-driven implementation. Focuses on the calculation method of battery and battery voltage gets. Battery management provided a good reference.