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https://github.com/DCC-EX/CommandStation-EX.git
synced 2025-07-28 09:53:45 +02:00
Initial STM32F4xx fast ADC read implementation
This commit is contained in:
pmantoine
@@ -131,31 +131,148 @@ void DCCTimer::reset() {
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while(true) {};
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}
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#define NUM_ADC_INPUTS NUM_ANALOG_INPUTS
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// TODO: may need to use uint32_t on STMF4xx variants with > 16 analog inputs!
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uint16_t ADCee::usedpins = 0;
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int * ADCee::analogvals = NULL;
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uint32_t * analogchans = NULL;
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bool adc1configured = false;
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int16_t ADCee::ADCmax() {
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return 4095;
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}
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int ADCee::init(uint8_t pin) {
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return analogRead(pin);
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uint id = pin - A0;
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int value = 0;
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PinName stmpin = digitalPin[analogInputPin[id]];
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uint32_t stmgpio = stmpin / 16; // 16-bits per GPIO port group on STM32
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uint32_t adcchan = STM_PIN_CHANNEL(pinmap_function(stmpin, PinMap_ADC)); // find ADC channel (only valid for ADC1!)
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GPIO_TypeDef * gpioBase;
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// Port config - find which port we're on and power it up
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switch(stmgpio) {
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case 0x00:
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RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN; //Power up PORTA
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gpioBase = GPIOA;
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break;
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case 0x01:
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RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN; //Power up PORTB
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gpioBase = GPIOB;
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break;
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case 0x02:
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RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN; //Power up PORTC
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gpioBase = GPIOC;
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break;
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}
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// Set pin mux mode to analog input
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gpioBase->MODER |= (0b011 << (stmpin << 1)); // Set pin mux to analog mode
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// Set the sampling rate for that analog input
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if (adcchan < 10)
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ADC1->SMPR2 |= (0b111 << (adcchan * 3)); // Channel sampling rate 480 cycles. 16MHz bus clock for ADC. 1/16MHz = 62.5ns. 480*62.5ns=30us
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else
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ADC1->SMPR1 |= (0b111 << ((adcchan - 10) * 3)); // Channel sampling rate 480 cycles. 16MHz bus clock for ADC. 1/16MHz = 62.5ns. 480*62.5ns=30us
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// Read the inital ADC value for this analog input
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ADC1->SQR3 = adcchan; // 1st conversion in regular sequence
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ADC1->CR2 |= (1 << 30); // Start 1st conversion SWSTART
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while(!(ADC1->SR & (1 << 1))); // Wait until conversion is complete
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value = ADC1->DR; // Read value from register
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if (analogvals == NULL)
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{
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analogvals = (int *)calloc(NUM_ADC_INPUTS+1, sizeof(int));
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analogchans = (uint32_t *)calloc(NUM_ADC_INPUTS+1, sizeof(uint32_t));
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}
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analogvals[id] = value; // Store sampled value
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analogchans[id] = adcchan; // Keep track of which ADC channel is used for reading this pin
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usedpins |= (1 << id); // This pin is now ready
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return value;
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}
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/*
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* Read function ADCee::read(pin) to get value instead of analogRead(pin)
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*/
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int ADCee::read(uint8_t pin, bool fromISR) {
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int current;
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if (!fromISR) noInterrupts();
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current = analogRead(pin);
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if (!fromISR) interrupts();
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return current;
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uint8_t id = pin - A0;
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// Was this pin initialised yet?
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if ((usedpins & (1<<id) ) == 0)
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return -1023;
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// We do not need to check (analogvals == NULL)
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// because usedpins would still be 0 in that case
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return analogvals[id];
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}
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/*
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* Scan function that is called from interrupt
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*/
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#pragma GCC push_options
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#pragma GCC optimize ("-O3")
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void ADCee::scan() {
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static uint id = 0; // id and mask are the same thing but it is faster to
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static uint16_t mask = 1; // increment and shift instead to calculate mask from id
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static bool waiting = false;
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if (waiting) {
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// look if we have a result
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if ((ADC1->SR & (1 << 1)))
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return; // no result, continue to wait
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// found value
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analogvals[id] = ADC1->DR;
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// advance at least one track
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// for scope debug TrackManager::track[1]->setBrake(0);
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waiting = false;
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id++;
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mask = mask << 1;
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if (id == NUM_ADC_INPUTS+1) {
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id = 0;
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mask = 1;
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}
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}
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if (!waiting) {
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if (usedpins == 0) // otherwise we would loop forever
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return;
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// look for a valid track to sample or until we are around
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while (true) {
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if (mask & usedpins) {
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// start new ADC aquire on id
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ADC1->SQR3 = analogchans[id]; //1st conversion in regular sequence
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ADC1->CR2 |= (1 << 30); //Start 1st conversion SWSTART
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// for scope debug TrackManager::track[1]->setBrake(1);
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waiting = true;
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return;
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}
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id++;
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mask = mask << 1;
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if (id == NUM_ADC_INPUTS+1) {
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id = 0;
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mask = 1;
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}
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}
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}
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}
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#pragma GCC pop_options
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void ADCee::begin() {
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noInterrupts();
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//ADC1 config sequence
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// TODO: currently defaults to ADC1, may need more to handle other members of STM32F4xx family
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RCC->APB2ENR |= (1 << 8); //Enable ADC1 clock (Bit8)
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// Set ADC prescaler - DIV8 ~ 40ms, DIV6 ~ 30ms, DIV4 ~ 20ms, DIV2 ~ 11ms
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ADC->CCR = (0 << 16); // Set prescaler 0=DIV2, 1=DIV4, 2=DIV6, 3=DIV8
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ADC1->CR1 &= ~(1 << 8); //SCAN mode disabled (Bit8)
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ADC1->CR1 &= ~(3 << 24); //12bit resolution (Bit24,25 0b00)
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ADC1->SQR1 = (1 << 20); //Set number of conversions projected (L[3:0] 0b0001) -> 1 conversion
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ADC1->CR2 &= ~(1 << 1); //Single conversion
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ADC1->CR2 &= ~(1 << 11); //Right alignment of data bits bit12....bit0
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ADC1->SQR1 &= ~(0x3FFFFFFF); //Clear whole 1st 30bits in register
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ADC1->SQR2 &= ~(0x3FFFFFFF); //Clear whole 1st 30bits in register
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ADC1->SQR3 &= ~(0x3FFFFFFF); //Clear whole 1st 30bits in register
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ADC1->CR2 |= (1 << 0); // Switch on ADC1
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interrupts();
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}
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#endif
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