95 lines
4 KiB
C
95 lines
4 KiB
C
/* Megumin LED display firmware
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* Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "adc.h"
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volatile int16_t adc_vcc_mv = 0;
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volatile int16_t adc_temp_celsius = 0;
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static volatile uint16_t adc_buf[2];
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void adc_init(void) {
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/* The ADC is used for temperature measurement. To compute the temperature from an ADC reading of the internal
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* temperature sensor, the supply voltage must also be measured. Thus we are using two channels.
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*
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* The ADC is triggered by compare channel 4 of timer 1. The trigger is set to falling edge to trigger on compare
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* match, not overflow.
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*/
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ADC1->CFGR1 = ADC_CFGR1_DMAEN | ADC_CFGR1_DMACFG | (2<<ADC_CFGR1_EXTEN_Pos) | (1<<ADC_CFGR1_EXTSEL_Pos);
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/* Clock from PCLK/4 instead of the internal exclusive high-speed RC oscillator. */
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ADC1->CFGR2 = (2<<ADC_CFGR2_CKMODE_Pos);
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/* Use the slowest available sample rate */
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ADC1->SMPR = (7<<ADC_SMPR_SMP_Pos);
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/* Internal VCC and temperature sensor channels */
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ADC1->CHSELR = ADC_CHSELR_CHSEL16 | ADC_CHSELR_CHSEL17;
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/* Enable internal voltage reference and temperature sensor */
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ADC->CCR = ADC_CCR_TSEN | ADC_CCR_VREFEN;
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/* Perform ADC calibration */
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ADC1->CR |= ADC_CR_ADCAL;
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while (ADC1->CR & ADC_CR_ADCAL)
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;
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/* Enable ADC */
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ADC1->CR |= ADC_CR_ADEN;
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ADC1->CR |= ADC_CR_ADSTART;
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/* Configure DMA 1 Channel 1 to get rid of all the data */
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DMA1_Channel1->CPAR = (unsigned int)&ADC1->DR;
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DMA1_Channel1->CMAR = (unsigned int)&adc_buf;
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DMA1_Channel1->CNDTR = sizeof(adc_buf)/sizeof(adc_buf[0]);
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DMA1_Channel1->CCR = (0<<DMA_CCR_PL_Pos);
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DMA1_Channel1->CCR |=
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DMA_CCR_CIRC /* circular mode so we can leave it running indefinitely */
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| (1<<DMA_CCR_MSIZE_Pos) /* 16 bit */
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| (1<<DMA_CCR_PSIZE_Pos) /* 16 bit */
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| DMA_CCR_MINC
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| DMA_CCR_TCIE; /* Enable transfer complete interrupt. */
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DMA1_Channel1->CCR |= DMA_CCR_EN; /* Enable channel */
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/* triggered on transfer completion. We use this to process the ADC data */
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NVIC_EnableIRQ(DMA1_Channel1_IRQn);
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NVIC_SetPriority(DMA1_Channel1_IRQn, 3);
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}
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void DMA1_Channel1_IRQHandler(void) {
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/* This interrupt takes either 1.2us or 13us. It can be pre-empted by the more timing-critical UART and LED timer
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* interrupts. */
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static int count = 0; /* oversampling accumulator sample count */
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static uint32_t adc_aggregate[2] = {0, 0}; /* oversampling accumulator */
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/* Clear the interrupt flag */
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DMA1->IFCR |= DMA_IFCR_CGIF1;
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adc_aggregate[0] += adc_buf[0];
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adc_aggregate[1] += adc_buf[1];
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if (++count == (1<<ADC_OVERSAMPLING)) {
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/* This has been copied from the code examples to section 12.9 ADC>"Temperature sensor and internal reference
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* voltage" in the reference manual with the extension that we actually measure the supply voltage instead of
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* hardcoding it. This is not strictly necessary since we're running off a bored little LDO but it's free and
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* the current supply voltage is a nice health value.
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*/
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adc_vcc_mv = (3300 * VREFINT_CAL)/(adc_aggregate[0]>>ADC_OVERSAMPLING);
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int32_t temperature = (((uint32_t)TS_CAL1) - ((adc_aggregate[1]>>ADC_OVERSAMPLING) * adc_vcc_mv / 3300)) * 1000;
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temperature = (temperature/5336) + 30;
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adc_temp_celsius = temperature;
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count = 0;
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adc_aggregate[0] = 0;
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adc_aggregate[1] = 0;
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}
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}
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