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Not use float in vbat measure (faster, less size), yes get little error (but less then 1mV)

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DiSlord 2020-03-14 15:21:26 +03:00
parent 922b66abdb
commit ec81a01226
1 changed files with 8 additions and 5 deletions
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13
adc.c
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@ -79,20 +79,23 @@ uint16_t adc_single_read(uint32_t chsel)
int16_t adc_vbat_read(void) int16_t adc_vbat_read(void)
{ {
// 13.9 Temperature sensor and internal reference voltage
// VREFINT_CAL calibrated on 3.3V, need get value in mV
#define ADC_FULL_SCALE 3300 #define ADC_FULL_SCALE 3300
#define VREFINT_CAL (*((uint16_t*)0x1FFFF7BA)) #define VREFINT_CAL (*((uint16_t*)0x1FFFF7BA))
adc_stop(); adc_stop();
float vbat = 0;
float vrefint = 0;
ADC->CCR |= ADC_CCR_VREFEN | ADC_CCR_VBATEN; ADC->CCR |= ADC_CCR_VREFEN | ADC_CCR_VBATEN;
// VREFINT == ADC_IN17 // VREFINT == ADC_IN17
vrefint = adc_single_read(ADC_CHSELR_CHSEL17); uint32_t vrefint = adc_single_read(ADC_CHSELR_CHSEL17);
// VBAT == ADC_IN18 // VBAT == ADC_IN18
// VBATEN enables resiter devider circuit. It consume vbat power. // VBATEN enables resiter devider circuit. It consume vbat power.
vbat = adc_single_read(ADC_CHSELR_CHSEL18); uint32_t vbat = adc_single_read(ADC_CHSELR_CHSEL18);
ADC->CCR &= ~(ADC_CCR_VREFEN | ADC_CCR_VBATEN); ADC->CCR &= ~(ADC_CCR_VREFEN | ADC_CCR_VBATEN);
touch_start_watchdog(); touch_start_watchdog();
uint16_t vbat_raw = (ADC_FULL_SCALE * VREFINT_CAL * vbat * 2 / (vrefint * ((1<<12)-1))); // vbat_raw = (3300 * 2 * vbat / 4095) * (VREFINT_CAL / vrefint)
// uint16_t vbat_raw = (ADC_FULL_SCALE * VREFINT_CAL * (float)vbat * 2 / (vrefint * ((1<<12)-1)));
// For speed divide not on 4095, divide on 4096, get little error, but no matter
uint16_t vbat_raw = ((ADC_FULL_SCALE * 2 * vbat)>>12) * VREFINT_CAL / vrefint;
if (vbat_raw < 100) { if (vbat_raw < 100) {
// maybe D2 is not installed // maybe D2 is not installed
return -1; return -1;