diff options
| -rw-r--r-- | fw/main.c | 20 |
1 files changed, 12 insertions, 8 deletions
@@ -89,7 +89,7 @@ void strobe_leds(void) { #define VREFINT_CAL (*(uint16_t *)0x1FFFF7BA) volatile int16_t adc_vcc_mv = 0; -volatile int16_t adc_temp_tenth_celsius = 0; +volatile int16_t adc_temp_celsius = 0; volatile uint16_t adc_buf[2]; @@ -541,7 +541,7 @@ void USART1_IRQHandler(void) { } } -#define ADC_OVERSAMPLING 4 +#define ADC_OVERSAMPLING 8 uint32_t vsense; void DMA1_Channel1_IRQHandler(void) { /* This interrupt takes either 1.2us or 13us. It can be pre-empted by the more timing-critical UART and LED timer @@ -556,13 +556,17 @@ void DMA1_Channel1_IRQHandler(void) { adc_aggregate[0] += adc_buf[0]; adc_aggregate[1] += adc_buf[1]; - if (count++ == (1<<ADC_OVERSAMPLING)) { - /* This has been cobbled together from online tutorials and ST documentation. The datasheet is pretty poor on - * this. */ + if (++count == (1<<ADC_OVERSAMPLING)) { + /* This has been copied from the code examples to section 12.9 ADC>"Temperature sensor and internal reference + * voltage" in the reference manual with the extension that we actually measure the supply voltage instead of + * hardcoding it. This is not strictly necessary since we're running off a bored little LDO but it's free and + * the current supply voltage is a nice health value. + */ adc_vcc_mv = (3300 * VREFINT_CAL)/(adc_aggregate[0]>>ADC_OVERSAMPLING); - vsense = ((adc_aggregate[1]>>ADC_OVERSAMPLING) * adc_vcc_mv)/4095 ; - adc_temp_tenth_celsius = 300 - (((TS_CAL1*adc_vcc_mv/4095) - vsense)*100)/43; - /* Reset oversampling state */ + int32_t temperature = (((uint32_t)TS_CAL1) - ((adc_aggregate[1]>>ADC_OVERSAMPLING) * adc_vcc_mv / 3300)) * 1000; + temperature = (temperature/5336) + 30; + adc_temp_celsius = temperature; + count = 0; adc_aggregate[0] = 0; adc_aggregate[1] = 0; |