mirror of https://github.com/ArduPilot/ardupilot
82 lines
2.2 KiB
C++
82 lines
2.2 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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int AVRAnalogIn::_num_channels = 0;
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int AVRAnalogIn::_active_channel = 0;
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int AVRAnalogIn::_channel_repeat_count = 0;
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AVRAnalogIn::AVRAnalogIn() {}
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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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cli();
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_num_channels++;
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sei();
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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 (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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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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/* 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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