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VCC calibration with internal reference

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This commit is contained in:
Alessandro Mauri 2026-05-29 09:57:13 +02:00
parent 7845689992
commit ec65e297fd
2 changed files with 12 additions and 8 deletions
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2
fw/funconfig.h
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@ -6,7 +6,6 @@
#define FUNCONF_DEBUG_HARDFAULT 0
#define CH32X035 1
#define I2C_TARGET I2C1
#define VCC_MV 3480
#define FRAME_TIME_MS 20 // 50Hz
#define PWM_FREQ_HZ 100000 // TIM3 PWM frequency
@ -26,6 +25,7 @@
#define CURRENT_ADC_CHANNEL ANALOG_1 // PA1
#define NTC_ADC_CHANNEL ANALOG_2 // PA2
#define TEMP_ADC_CHANNEL ANALOG_3 // PA3
#define VREF_INT_CHANNEL 15 // Internal channel set to 1.2V reference
#define ENCODER_INV true
#define ENCODER_FAST 3

18
fw/main.c
View File

@ -29,6 +29,7 @@ u8g2_t *u8g2;
int16_t encoder = 0; // rotary encoder counter
uint32_t last_interrupt = 0; // last time the encoder interrupt was triggered
struct pd_profile_t pd_profile;
uint16_t vcc_mv = 3300;
// Convert the raw adc reading to a temperature in celsius with the ntc lut,
// linearly interpolating between positions
@ -48,7 +49,7 @@ static inline int16_t get_current_ma(uint16_t adc_reading)
{
// Rshunt = 4 milliOhm
// Gain = 100
u32 mv = ((u32)adc_reading * VCC_MV) / 4096;
u32 mv = ((u32)adc_reading * vcc_mv) / 4096;
return (mv * 10) / 4;
}
@ -405,15 +406,16 @@ static inline void setup(void)
funPinMode(PIN_TEMP, GPIO_CFGLR_IN_ANALOG);
// Analog inputs setup (dma and injection conversion)
uint8_t adc_channels[3] = {
uint8_t adc_channels[] = {
VBUS_ADC_CHANNEL,
CURRENT_ADC_CHANNEL,
NTC_ADC_CHANNEL
};
uint8_t adc_injected[1] = {
TEMP_ADC_CHANNEL
uint8_t adc_injected[] = {
TEMP_ADC_CHANNEL,
VREF_INT_CHANNEL
};
setup_adc_and_dma(adc_channels, 3, adc_injected, 1);
setup_adc_and_dma(adc_channels, sizeof(adc_channels), adc_injected, sizeof(adc_injected));
// Digital pin configuration
funPinMode(PIN_12V, GPIO_CFGLR_OUT_10Mhz_PP);
@ -518,7 +520,7 @@ __attribute__((noreturn)) int main(void)
static int16_t temp_c, tip_temp_c;
static uint16_t power;
static uint16_t duty;
vbus_mv = U16_FP_EMA_K4(vbus_mv, ((u32)adc_buffer[0]*VCC_MV*11)/4096);
vbus_mv = U16_FP_EMA_K4(vbus_mv, ((u32)adc_buffer[0]*vcc_mv*11)/4096);
current_ma = U16_FP_EMA_K4(current_ma, get_current_ma(adc_buffer[1]));
temp_c = I16_FP_EMA_K4(temp_c, get_temp_c(adc_buffer[2]));
power = ((u32)vbus_mv*current_ma)/1000000;
@ -527,7 +529,9 @@ __attribute__((noreturn)) int main(void)
if (!pwm || !enabled) {
Delay_Ms(TURN_OFF_DELAY);
adc_injection_conversion();
u16 tip_mv = ((u32)injection_results[0]*VCC_MV)/4096;
// Calibrate VCC with the internal reference value
vcc_mv = ((uint32_t)1200 * 4096)/injection_results[1];
u16 tip_mv = ((u32)injection_results[0]*vcc_mv)/4096;
// Tip calibration factors
const fp16_t tip_k = num2fp(0, 14473, 5);
const fp16_t tip_off = num2fp(0, 0, 0);