79 строки
2.5 KiB
ReStructuredText
79 строки
2.5 KiB
ReStructuredText
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Kernel driver da9052
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====================
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Supported chips:
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* Dialog Semiconductors DA9052-BC and DA9053-AA/Bx PMICs
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Prefix: 'da9052'
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Datasheet: Datasheet is not publicly available.
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Authors: David Dajun Chen <dchen@diasemi.com>
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Description
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-----------
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The DA9052/53 provides an Analogue to Digital Converter (ADC) with 10 bits
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resolution and track and hold circuitry combined with an analogue input
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multiplexer. The analogue input multiplexer will allow conversion of up to 10
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different inputs. The track and hold circuit ensures stable input voltages at
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the input of the ADC during the conversion.
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The ADC is used to measure the following inputs:
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========= ===================================================================
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Channel 0 VDDOUT - measurement of the system voltage
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Channel 1 ICH - internal battery charger current measurement
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Channel 2 TBAT - output from the battery NTC
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Channel 3 VBAT - measurement of the battery voltage
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Channel 4 ADC_IN4 - high impedance input (0 - 2.5V)
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Channel 5 ADC_IN5 - high impedance input (0 - 2.5V)
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Channel 6 ADC_IN6 - high impedance input (0 - 2.5V)
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Channel 7 XY - TSI interface to measure the X and Y voltage of the touch
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screen resistive potentiometers
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Channel 8 Internal Tjunc. - sense (internal temp. sensor)
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Channel 9 VBBAT - measurement of the backup battery voltage
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========= ===================================================================
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By using sysfs attributes we can measure the system voltage VDDOUT, the battery
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charging current ICH, battery temperature TBAT, battery junction temperature
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TJUNC, battery voltage VBAT and the back up battery voltage VBBAT.
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Voltage Monitoring
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------------------
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Voltages are sampled by a 10 bit ADC.
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The battery voltage is calculated as:
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Milli volt = ((ADC value * 1000) / 512) + 2500
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The backup battery voltage is calculated as:
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Milli volt = (ADC value * 2500) / 512;
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The voltages on ADC channels 4, 5 and 6 are calculated as:
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Milli volt = (ADC value * 2500) / 1023
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Temperature Monitoring
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----------------------
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Temperatures are sampled by a 10 bit ADC. Junction and battery temperatures
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are monitored by the ADC channels.
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The junction temperature is calculated:
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Degrees celsius = 1.708 * (TJUNC_RES - T_OFFSET) - 108.8
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The junction temperature attribute is supported by the driver.
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The battery temperature is calculated:
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Degree Celsius = 1 / (t1 + 1/298) - 273
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where t1 = (1/B)* ln(( ADCval * 2.5)/(R25*ITBAT*255))
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Default values of R25, B, ITBAT are 10e3, 3380 and 50e-6 respectively.
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