118 lines
4.6 KiB
C
118 lines
4.6 KiB
C
/* Megumin LED display firmware
|
|
* Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
|
|
*
|
|
* 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/>.
|
|
*/
|
|
|
|
#include "adc.h"
|
|
|
|
volatile struct adc_measurements adc_data = {0};
|
|
|
|
enum adc_channels {
|
|
VREF_CH,
|
|
VMEAS_A,
|
|
VMEAS_B,
|
|
TEMP_CH,
|
|
NCH
|
|
};
|
|
static volatile uint16_t adc_buf[NCH];
|
|
|
|
void adc_init(void) {
|
|
/* The ADC is used for temperature measurement. To compute the temperature from an ADC reading of the internal
|
|
* temperature sensor, the supply voltage must also be measured. Thus we are using two channels.
|
|
*
|
|
* The ADC is triggered by compare channel 4 of timer 1. The trigger is set to falling edge to trigger on compare
|
|
* match, not overflow.
|
|
*/
|
|
ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos);
|
|
/* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */
|
|
ADC1->CFGR2 = (2<<ADC_CFGR2_CKMODE_Pos); /* Use PCLK/4=12MHz */
|
|
/* Sampling time 13.5 ADC clock cycles -> total conversion time 2.17us*/
|
|
ADC1->SMPR = (2<<ADC_SMPR_SMP_Pos);
|
|
/* Internal VCC and temperature sensor channels */
|
|
ADC1->CHSELR = ADC_CHSELR_CHSEL0 | ADC_CHSELR_CHSEL1 | ADC_CHSELR_CHSEL16 | ADC_CHSELR_CHSEL17;
|
|
/* Enable internal voltage reference and temperature sensor */
|
|
ADC->CCR = ADC_CCR_TSEN | ADC_CCR_VREFEN;
|
|
/* Perform ADC calibration */
|
|
ADC1->CR |= ADC_CR_ADCAL;
|
|
while (ADC1->CR & ADC_CR_ADCAL)
|
|
;
|
|
/* Enable ADC */
|
|
ADC1->CR |= ADC_CR_ADEN;
|
|
ADC1->CR |= ADC_CR_ADSTART;
|
|
|
|
/* Configure DMA 1 Channel 1 to get rid of all the data */
|
|
DMA1_Channel1->CPAR = (unsigned int)&ADC1->DR;
|
|
DMA1_Channel1->CMAR = (unsigned int)&adc_buf;
|
|
DMA1_Channel1->CNDTR = NCH;
|
|
DMA1_Channel1->CCR = (0<<DMA_CCR_PL_Pos);
|
|
DMA1_Channel1->CCR |=
|
|
DMA_CCR_CIRC /* circular mode so we can leave it running indefinitely */
|
|
| (1<<DMA_CCR_MSIZE_Pos) /* 16 bit */
|
|
| (1<<DMA_CCR_PSIZE_Pos) /* 16 bit */
|
|
| DMA_CCR_MINC
|
|
| DMA_CCR_TCIE; /* Enable transfer complete interrupt. */
|
|
DMA1_Channel1->CCR |= DMA_CCR_EN; /* Enable channel */
|
|
|
|
/* triggered on transfer completion. We use this to process the ADC data */
|
|
NVIC_EnableIRQ(DMA1_Channel1_IRQn);
|
|
NVIC_SetPriority(DMA1_Channel1_IRQn, 3<<5);
|
|
}
|
|
|
|
uint16_t buf_a[256];
|
|
uint16_t buf_b[256];
|
|
int bufp = 0;
|
|
|
|
void DMA1_Channel1_IRQHandler(void) {
|
|
/* This interrupt takes either 1.2us or 13us. It can be pre-empted by the more timing-critical UART and LED timer
|
|
* interrupts. */
|
|
static int count = 0; /* oversampling accumulator sample count */
|
|
static uint32_t adc_aggregate[NCH] = {0}; /* oversampling accumulator */
|
|
|
|
/* Clear the interrupt flag */
|
|
DMA1->IFCR |= DMA_IFCR_CGIF1;
|
|
|
|
for (int i=0; i<NCH; i++)
|
|
adc_aggregate[i] += adc_buf[i];
|
|
|
|
if (++count == (1<<ADC_OVERSAMPLING)) {
|
|
for (int i=0; i<NCH; i++)
|
|
adc_aggregate[i] >>= ADC_OVERSAMPLING;
|
|
/* This has been copied from the code examples to section 12.9 ADC>"Temperature sensor and internal reference
|
|
* voltage" in the reference manual with the extension that we actually measure the supply voltage instead of
|
|
* hardcoding it. This is not strictly necessary since we're running off a bored little LDO but it's free and
|
|
* the current supply voltage is a nice health value.
|
|
*/
|
|
adc_data.adc_vcc_mv = (3300 * VREFINT_CAL)/(adc_aggregate[VREF_CH]);
|
|
|
|
int64_t read = adc_aggregate[TEMP_CH] * 10 * 10000;
|
|
int64_t vcc = adc_data.adc_vcc_mv;
|
|
int64_t cal = TS_CAL1 * 10 * 10000;
|
|
adc_data.adc_temp_celsius_tenths = 300 + ((read/4096 * vcc) - (cal/4096 * 3300))/43000;
|
|
|
|
adc_data.adc_vmeas_a_mv = (adc_aggregate[VMEAS_A]*13300L)/4096 * vcc / 3300;
|
|
adc_data.adc_vmeas_b_mv = (adc_aggregate[VMEAS_B]*13300L)/4096 * vcc / 3300;
|
|
|
|
buf_a[bufp] = adc_data.adc_vmeas_a_mv;
|
|
buf_b[bufp] = adc_data.adc_vmeas_b_mv;
|
|
if (++bufp >= sizeof(buf_a)/sizeof(buf_a[0])) {
|
|
bufp = 0;
|
|
}
|
|
|
|
count = 0;
|
|
for (int i=0; i<NCH; i++)
|
|
adc_aggregate[i] = 0;
|
|
}
|
|
}
|
|
|