Quectel LTE Module Series User manual

SC20 Charging User Guide
LTE Module Series
Rev. SC20_Charging_User_Guide_V1.0
Date: 2016-09-26
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Our aim is to provide customers with timely and comprehensive service. For any
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http://www.quectel.com/support/salesupport.aspx
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QUECTEL OFFERS THE INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION
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Copyright © Quectel Wireless Solutions Co., Ltd. 2016. All rights reserved.
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About the Document
History
Revision
Date
Author
Description
1.0
2016-09-26
Luffy ZHANG
Initial
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Contents
About the Document................................................................................................................................ 2
Contents.................................................................................................................................................... 3
Table Index ............................................................................................................................................... 4
1Introduction....................................................................................................................................... 5
2Debug................................................................................................................................................. 6
2.1. Related Code Files and Location.......................................................................................... 6
2.2. Debug................................................................................................................................... 6
3Compile and Download................................................................................................................... 11
4Charge.............................................................................................................................................. 12
4.1. Charging Process ...............................................................................................................12
4.2. Set Power-on/off Voltage ....................................................................................................12
4.3. The Maximum Charging Time.............................................................................................14
4.4. Abnormality.........................................................................................................................14
4.5. Query Device Information................................................................................................... 14
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Table Index
TABLE 1: RELATED CODE FILES AND LOCATIONS........................................................................................ 6
TABLE 2: BATTERY-TEMPERATURE MONITORING CALCULATIONS ......................................................... 10
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1Introduction
This document mainly describes debug codes for charging on Quectel SC20 module, which will help
customer to better understand the charging process.
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2Debug
2.1. Related Code Files and Location
Table 1: Related Code Files and Locations
Linux power_supply standard architecture enables power management on Android OS and data can be
sent to user space through Uevent mechanism.
2.2. Debug
Device Registration
The code for device registration is as follows:
static int qpnp_lbc_main_probe(struct spmi_device *spmi)
{
xxx
rc = power_supply_register(chip->dev, &chip->batt_psy); //Device registration
xxx
}
Code Files and Locations
Description
android/kernel/drivers/power/qpnp-linear-charger.c
Driver file for charging
android/kernel/arch/arm/boot/dts/qcom/batterydata-
palladium.dtsi
Battery parameters
android/kernel/arch/arm/boot/dts/qcom/msm-pm890
9.dtsi
Charging parameters
android/kernel/arch/arm/boot/dts/qcom/msm8909-p
m8909-mtp.dtsi
Charging switch
android/kernel/drivers/hwmon/qpnp-adc-common.c
Thermistor voltage and temperature table
qpnp-linear-charger.c
Driver file for charging, it is about device
registration, DTS parse, charging controlling, etc.
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static int qpnp_lbc_probe(struct spmi_device *spmi)
{
if (is_parallel_charger(spmi))
return qpnp_lbc_parallel_probe(spmi);
else
return qpnp_lbc_main_probe(spmi);
}
static int __init qpnp_lbc_init(void)
{
return spmi_driver_register(&qpnp_lbc_driver);
}
module_init(qpnp_lbc_init);
static void __exit qpnp_lbc_exit(void)
{
spmi_driver_unregister(&qpnp_lbc_driver);
}
module_exit(qpnp_lbc_exit);
MODULE_DESCRIPTION("QPNP Linear charger driver");
MODULE_LICENSE("GPL v2");
DTS Parse
DTS (Device Tree Source) is parsed by probe function.
static int qpnp_charger_read_dt_props(struct qpnp_lbc_chip *chip)
{ xxx
xxx
}
Charging Controlling
e.g.: when the battery temperature changes, charging current will become smaller to protect battery.
Please refer to the following code:
static void qpnp_lbc_set_appropriate_current(struct qpnp_lbc_chip *chip)
{
unsigned int chg_current = chip->usb_psy_ma;
if (chip->bat_is_cool && chip->cfg_cool_bat_chg_ma)
chg_current = min(chg_current, chip->cfg_cool_bat_chg_ma);
if (chip->bat_is_warm && chip->cfg_warm_bat_chg_ma)
chg_current = min(chg_current, chip->cfg_warm_bat_chg_ma);
if (chip->therm_lvl_sel != 0 && chip->thermal_mitigation)
chg_current = min(chg_current,
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chip->thermal_mitigation[chip->therm_lvl_sel]);
pr_debug("setting charger current %d mA\n", chg_current);
qpnp_lbc_ibatmax_set(chip, chg_current);
}
Battery Parameters
Battery parameters can be configured to calculate battery capacity, such as OCV (Open Circuit Voltage)
under different temperature and battery percentage.
qcom,pc-temp-ocv-lut{ xxx
}
Charging Parameters
Charging parameters includes high temperature percentage, low temperature percentage, battery cooling
threshold, battery warming threshold, charging current, etc., as shown below:
pm8909_chg: qcom,charger{
xxx
qcom,batt-hot-percentage = <35>; //High temperature percentage
qcom,batt-cold-percentage = <70>; //Low temperature percentage
qcom,cool-bat-decidegc = <100>; //Cooling threshold
qcom,warm-bat-decidegc = <450>; //Warming threshold
qcom,ibatmax-warm-ma = <360>; //Cooling current
qcom,ibatmax-cool-ma = <360>; //Warming current
xxx
}
Charging Switch
SC20 applies PMU internal charging and IC is pm8909, so customer needs to turn on pm8909 charger IC,
as follows:
&pm8909_chg {
status = "ok";
/* qcom,charging-disabled; */ //Comment out this line.
};
Thermistor Voltage and Temperature Table:
Thermistor voltage and temperature table is used to judge the accuracy of battery temperature that is
read.
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static const struct qpnp_vadc_map_pt adcmap_btm_threshold[] = {
{XXX, YYY}, //The former is the temperature value, and the latter is the voltage
}
The table is customized, it needs hardware engineers to get values from battery vendors and fill in.
High Temperature Shutdown
High temperature protection has been enabled on SC20, when the battery temperature is above 68
degrees, it will automatically shut down.
High temperature shutdown related files and codes are presented as follows:
1. android/frameworks/base/services/core/java/com/android/server/BatteryService.java: for executing
shutdown action.
private void shutdownIfOverTempLocked() {
//Shut down gracefully if temperature is too high (>68°C by default)
//Wait until the system has booted before attempting to display the shutdown dialog.
if (mBatteryProps.batteryTemperature > mShutdownBatteryTemperature) {
mHandler.post(new Runnable() {
@Override
public void run() {
if (ActivityManagerNative.isSystemReady()) {
Slog.e(TAG, "silent_reboot shutdownIfOverTempLocked");
Intent intent = new Intent(Intent.ACTION_REQUEST_SHUTDOWN);
intent.putExtra(Intent.EXTRA_KEY_CONFIRM, false);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
mContext.startActivityAsUser(intent, UserHandle.CURRENT);
}
}
});
}
}
2. android/frameworks/base/core/res/res/values/config.xml: set the temperature that triggers shutdown.
<!-- Shutdown if the battery temperature exceeds (this value * 0.1) Celsius. -->
<integer name="config_shutdownBatteryTemperature">680</integer>
If module shuts down immediately after being turned on, customer should first make sure that the battery
has power, then check whether it is caused by high temperature or not.
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