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stmhal/adc: Provide more accurate measure of VBAT and VREFINT. 

By using factory calibration values.
This commit is contained in:
Damien George 2016-11-30 12:04:21 +11:00
parent 295266178c
commit 87215a0f04
1 changed files with 36 additions and 5 deletions
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41
stmhal/adc.c
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@ -55,14 +55,28 @@
#define ADCx_CLK_ENABLE __ADC1_CLK_ENABLE
#define ADC_NUM_CHANNELS (19)
#if defined(MCU_SERIES_F4) || defined(MCU_SERIES_F7)
#if defined(MCU_SERIES_F4)
#define ADC_FIRST_GPIO_CHANNEL (0)
#define ADC_LAST_GPIO_CHANNEL (15)
#define ADC_CAL_ADDRESS (0x1fff7a2a)
#elif defined(MCU_SERIES_F7)
#define ADC_FIRST_GPIO_CHANNEL (0)
#define ADC_LAST_GPIO_CHANNEL (15)
#define ADC_CAL_ADDRESS (0x1ff0f44a)
#elif defined(MCU_SERIES_L4)
#define ADC_FIRST_GPIO_CHANNEL (1)
#define ADC_LAST_GPIO_CHANNEL (16)
#define ADC_CAL_ADDRESS (0x1fff75aa)
#else
#error Unsupported processor
#endif
#if defined(STM32F405xx) || defined(STM32F415xx) || \
@ -84,6 +98,10 @@
#define CORE_TEMP_V25 (943) /* (0.76v/3.3v)*(2^ADC resoultion) */
#define CORE_TEMP_AVG_SLOPE (3) /* (2.5mv/3.3v)*(2^ADC resoultion) */
// scale and calibration values for VBAT and VREF
#define ADC_SCALE (3.3f / 4095)
#define VREFIN_CAL ((uint16_t *)ADC_CAL_ADDRESS)
typedef struct _pyb_obj_adc_t {
mp_obj_base_t base;
mp_obj_t pin_name;
@ -513,6 +531,9 @@ int adc_read_core_temp(ADC_HandleTypeDef *adcHandle) {
}
#if MICROPY_PY_BUILTINS_FLOAT
// correction factor for reference value
STATIC volatile float adc_refcor = 1.0f;
float adc_read_core_vbat(ADC_HandleTypeDef *adcHandle) {
uint32_t raw_value = adc_config_and_read_channel(adcHandle, ADC_CHANNEL_VBAT);
@ -520,8 +541,16 @@ float adc_read_core_vbat(ADC_HandleTypeDef *adcHandle) {
// be 12-bits.
raw_value <<= (12 - adc_get_resolution(adcHandle));
// multiplier is 3.3/4095
return raw_value * VBAT_DIV * 0.8058608058608059e-3f;
#if defined(MCU_SERIES_F4) || defined(MCU_SERIES_F7)
// ST docs say that (at least on STM32F42x and STM32F43x), VBATE must
// be disabled when TSVREFE is enabled for TEMPSENSOR and VREFINT
// conversions to work. VBATE is enabled by the above call to read
// the channel, and here we disable VBATE so a subsequent call for
// TEMPSENSOR or VREFINT works correctly.
ADC->CCR &= ~ADC_CCR_VBATE;
#endif
return raw_value * VBAT_DIV * ADC_SCALE * adc_refcor;
}
float adc_read_core_vref(ADC_HandleTypeDef *adcHandle) {
@ -531,8 +560,10 @@ float adc_read_core_vref(ADC_HandleTypeDef *adcHandle) {
// be 12-bits.
raw_value <<= (12 - adc_get_resolution(adcHandle));
// multiplier is 3.3/4095
return raw_value * 0.8058608058608059e-3f;
// update the reference correction factor
adc_refcor = ((float)(*VREFIN_CAL)) / ((float)raw_value);
return (*VREFIN_CAL) * ADC_SCALE;
}
#endif