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