ardupilot/libraries/AP_HAL_AVR/AnalogIn_Common.cpp

126 lines
3.5 KiB
C++

#include <avr/io.h>
#include <avr/interrupt.h>
#include <AP_HAL.h>
#include "AnalogIn.h"
using namespace AP_HAL_AVR;
extern const AP_HAL::HAL& hal;
/* CHANNEL_READ_REPEAT: how many reads on a channel before using the value.
* This seems to be determined empirically */
#define CHANNEL_READ_REPEAT 2
/* Static variable instances */
ADCSource* AVRAnalogIn::_channels[AVR_INPUT_MAX_CHANNELS] = {NULL};
int16_t AVRAnalogIn::_num_channels = 0;
int16_t AVRAnalogIn::_active_channel = 0;
int16_t AVRAnalogIn::_channel_repeat_count = 0;
AVRAnalogIn::AVRAnalogIn() :
_vcc(ADCSource(ANALOG_INPUT_BOARD_VCC))
{}
void AVRAnalogIn::init(void* machtnichts) {
/* Register AVRAnalogIn::_timer_event with the scheduler. */
hal.scheduler->register_timer_process(_timer_event);
/* Register each private channel with AVRAnalogIn. */
_register_channel(&_vcc);
}
ADCSource* AVRAnalogIn::_find_or_create_channel(int16_t pin, float scale) {
for(int16_t i = 0; i < _num_channels; i++) {
if (_channels[i]->_pin == pin) {
return _channels[i];
}
}
return _create_channel(pin, scale);
}
ADCSource* AVRAnalogIn::_create_channel(int16_t chnum, float scale) {
ADCSource *ch = new ADCSource(chnum, scale);
_register_channel(ch);
return ch;
}
void AVRAnalogIn::_register_channel(ADCSource* ch) {
if (_num_channels >= AVR_INPUT_MAX_CHANNELS) {
for(;;) {
hal.console->print_P(PSTR(
"Error: AP_HAL_AVR::AVRAnalogIn out of channels\r\n"));
hal.scheduler->delay(1000);
}
}
_channels[_num_channels] = ch;
/* Need to lock to increment _num_channels as it is used
* by the interrupt to access _channels */
uint8_t sreg = SREG;
cli();
_num_channels++;
SREG = sreg;
if (_num_channels == 1) {
/* After registering the first channel, we can enable the ADC */
PRR0 &= ~_BV(PRADC);
ADCSRA |= _BV(ADEN);
}
}
void AVRAnalogIn::_timer_event(uint32_t t) {
if (_channels[_active_channel]->_pin == ANALOG_INPUT_NONE) {
_channels[_active_channel]->new_sample(0);
goto next_channel;
}
if (ADCSRA & _BV(ADSC)) {
/* ADC Conversion is still running - this should not happen, as we
* are called at 1khz. */
return;
}
if (_num_channels == 0) {
/* No channels are registered - nothing to be done. */
return;
}
_channel_repeat_count++;
if (_channel_repeat_count < CHANNEL_READ_REPEAT) {
/* Start a new conversion, throw away the current conversion */
ADCSRA |= _BV(ADSC);
return;
} else {
_channel_repeat_count = 0;
}
/* Read the conversion registers. */
{
uint8_t low = ADCL;
uint8_t high = ADCH;
uint16_t sample = low | (((uint16_t)high) << 8);
/* Give the active channel a new sample */
_channels[_active_channel]->new_sample( sample );
}
next_channel:
/* Move to the next channel */
_active_channel = (_active_channel + 1) % _num_channels;
/* Setup the next channel's conversion */
_channels[_active_channel]->setup_read();
/* Start conversion */
ADCSRA |= _BV(ADSC);
}
AP_HAL::AnalogSource* AVRAnalogIn::channel(int16_t ch) {
return this->channel(ch, 1.0);
}
AP_HAL::AnalogSource* AVRAnalogIn::channel(int16_t ch, float scale) {
if (ch == ANALOG_INPUT_BOARD_VCC) {
return &_vcc;
} else {
return _find_or_create_channel(ch, scale);
}
}