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AP_HAL_ChibiOS: fix race condition on analog reading

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