ardupilot/libraries/AP_IOMCU/iofirmware/analog.cpp

89 lines
2.1 KiB
C++

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
analog capture for IOMCU. This uses direct register access to avoid
using up a DMA channel and to minimise latency. We capture a single
sample at a time
*/
#include "ch.h"
#include "hal.h"
#include "analog.h"
#if HAL_USE_ADC != TRUE
#error "HAL_USE_ADC must be set"
#endif
/*
initialise ADC capture
*/
void adc_init(void)
{
adc_lld_init();
rccEnableADC1(true);
/* set channels 4 and 5 for 28.5us sample time */
ADC1->SMPR2 = ADC_SMPR2_SMP_AN4(ADC_SAMPLE_28P5) | ADC_SMPR2_SMP_AN5(ADC_SAMPLE_28P5);
/* capture a single sample at a time */
ADC1->SQR1 = 0;
ADC1->SQR2 = 0;
}
/*
capture one sample on a channel
*/
static uint16_t adc_sample_channel(uint32_t channel)
{
// clear EOC
ADC1->SR = 0;
/* capture one sample */
ADC1->SQR3 = channel;
ADC1->CR2 |= ADC_CR2_ADON;
/* wait for the conversion to complete */
uint32_t counter = 16;
while (!(ADC1->SR & ADC_SR_EOC)) {
if (--counter == 0) {
// ensure EOC is clear
ADC1->SR = 0;
return 0xffff;
}
}
// return sample (this also clears EOC flag)
return ADC1->DR;
}
/*
capture VSERVO in mV
*/
uint16_t adc_sample_vservo(void)
{
const uint32_t channel = ADC_SQR3_SQ1_N(ADC_CHANNEL_IN4);
return adc_sample_channel(channel);
}
/*
capture VRSSI in mV
*/
uint16_t adc_sample_vrssi(void)
{
const uint32_t channel = ADC_SQR3_SQ1_N(ADC_CHANNEL_IN5);
return adc_sample_channel(channel);
}