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AP_HAL_ChibiOS: fix race condition on analog reading

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This commit is contained in:
Michael du Breuil 2018-05-18 00:43:55 -07:00 committed by Andrew Tridgell
parent 80d1a1de9a
commit a832bdfd04
2 changed files with 40 additions and 28 deletions
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67
libraries/AP_HAL_ChibiOS/AnalogIn.cpp
View File

@ -73,19 +73,24 @@ AnalogSource::AnalogSource(int16_t pin, float initial_value) :
_sum_value(0),
_sum_ratiometric(0)
{
_semaphore = hal.util->new_semaphore();
}
float AnalogSource::read_average()
{
if (_sum_count == 0) {
return _value;
if (_semaphore->take(1)) {
if (_sum_count == 0) {
_semaphore->give();
return _value;
}
_value = _sum_value / _sum_count;
_value_ratiometric = _sum_ratiometric / _sum_count;
_sum_value = 0;
_sum_ratiometric = 0;
_sum_count = 0;
_semaphore->give();
}
_value = _sum_value / _sum_count;
_value_ratiometric = _sum_ratiometric / _sum_count;
_sum_value = 0;
_sum_ratiometric = 0;
_sum_count = 0;
return _value;
}
@ -140,13 +145,16 @@ void AnalogSource::set_pin(uint8_t pin)
if (_pin == pin) {
return;
}
_pin = pin;
_sum_value = 0;
_sum_ratiometric = 0;
_sum_count = 0;
_latest_value = 0;
_value = 0;
_value_ratiometric = 0;
if (_semaphore->take(HAL_SEMAPHORE_BLOCK_FOREVER)) {
_pin = pin;
_sum_value = 0;
_sum_ratiometric = 0;
_sum_count = 0;
_latest_value = 0;
_value = 0;
_value_ratiometric = 0;
_semaphore->give();
}
}
/*
@ -154,20 +162,23 @@ void AnalogSource::set_pin(uint8_t pin)
*/
void AnalogSource::_add_value(float v, float vcc5V)
{
_latest_value = v;
_sum_value += v;
if (vcc5V < 3.0f) {
_sum_ratiometric += v;
} else {
// this compensates for changes in the 5V rail relative to the
// 3.3V reference used by the ADC.
_sum_ratiometric += v * 5.0f / vcc5V;
}
_sum_count++;
if (_sum_count == 254) {
_sum_value /= 2;
_sum_ratiometric /= 2;
_sum_count /= 2;
if (_semaphore->take(1)) {
_latest_value = v;
_sum_value += v;
if (vcc5V < 3.0f) {
_sum_ratiometric += v;
} else {
// this compensates for changes in the 5V rail relative to the
// 3.3V reference used by the ADC.
_sum_ratiometric += v * 5.0f / vcc5V;
}
_sum_count++;
if (_sum_count == 254) {
_sum_value /= 2;
_sum_ratiometric /= 2;
_sum_count /= 2;
}
_semaphore->give();
}
}

1
libraries/AP_HAL_ChibiOS/AnalogIn.h
View File

@ -50,6 +50,7 @@ private:
float _sum_ratiometric;
void _add_value(float v, float vcc5V);
float _pin_scaler();
AP_HAL::Semaphore *_semaphore;
};
class ChibiOS::AnalogIn : public AP_HAL::AnalogIn {