ttrftech/NanoVNA
1
0
Fork 0
mirror of https://github.com/ttrftech/NanoVNA.git synced 2025-12-06 03:31:59 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

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

Browse source
This commit is contained in:
DiSlord 2020-03-14 15:21:26 +03:00
parent 922b66abdb
commit ec81a01226
1 changed files with 8 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
adc.c
View file

@ -79,20 +79,23 @@ uint16_t adc_single_read(uint32_t chsel)
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 VREFINT_CAL (*((uint16_t*)0x1FFFF7BA))
adc_stop();
float vbat = 0;
float vrefint = 0;
ADC->CCR |= ADC_CCR_VREFEN | ADC_CCR_VBATEN;
// VREFINT == ADC_IN17
vrefint = adc_single_read(ADC_CHSELR_CHSEL17);
uint32_t vrefint = adc_single_read(ADC_CHSELR_CHSEL17);
// VBAT == ADC_IN18
// 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);
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) {
// maybe D2 is not installed
return -1;