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Diffstat (limited to 'fw')
-rw-r--r--fw/main.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/fw/main.c b/fw/main.c
index 108d3a1..55fb769 100644
--- a/fw/main.c
+++ b/fw/main.c
@@ -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;