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don't cache temperature samples at all (#2392)

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Matthew Kennedy 2021-02-24 03:15:03 -10:00 committed by GitHub
parent 392a7539be
commit 9c591c7733
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1 changed files with 4 additions and 15 deletions
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19
firmware/hw_layer/ports/stm32/stm32_adc_v2.cpp
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@ -71,25 +71,14 @@ static const ADCConversionGroup tempSensorConvGroup = {
#endif
};
// 4x oversample is plenty
static constexpr int oversample = 4;
static adcsample_t samples[oversample];
float getMcuTemperature() {
// 4x oversample is plenty
constexpr int oversample = 4;
// Buffer is a full 32 bytes to occupy a full cache line
__ALIGNED(32) adcsample_t samples[16];
// Temperature sensor is only physically wired to ADC1
adcConvert(&ADCD1, &tempSensorConvGroup, samples, oversample);
#if CORTEX_MODEL == 7
// The STM32F7xx/STM32H7xx has a data cache
// DMA operations DO NOT invalidate cache lines, since the ARM m7 doesn't have
// anything like a CCI that maintains coherency across multiple bus masters.
// As a result, we have to manually invalidate the D-cache any time we (the CPU)
// would like to read something that somebody else wrote (ADC via DMA, in this case)
SCB_InvalidateDCache_by_Addr(reinterpret_cast<uint32_t*>(samples), sizeof(samples));
#endif /* CORTEX_MODEL == 7 */
uint32_t sum = 0;
for (size_t i = 0; i < oversample; i++) {
sum += samples[i];