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#include "stm32f0xx.h"
// GPIO A
#define PINOUT_DISP_CLK (5)
#define PINOUT_DISP_DIO (6)
#define PINOUT_POT (7)
// GPIO B
#define PINOUT_LED_1 (3)
#define PINOUT_LED_2 (5)
#define PINOUT_LED_3 (4)
#define PINOUT_LED_4 (6)
const unsigned short leds[] = {PINOUT_LED_1, PINOUT_LED_2, PINOUT_LED_3, PINOUT_LED_4};
#define PINOUT_BTN (8)
/*
* This function configures the I/O-ports that are used by the I/O-shield. It
* uses register RCC_AHBENR to enable the clocks for the ports that are used,
* register GPIOx_MODER to configure pins as input, analog or output and
* GPIOx_PUPDR to configure pull-up and pull-down resistors.
*/
void shieldConfig() {
// enable clock for I/O ports A and B
RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
// enable clock for the ADC peripheral
RCC->APB2ENR |= RCC_APB2ENR_ADC1EN;
// clear mode register configuration bits
GPIOB->MODER &= ~((0b11 << (PINOUT_LED_1 * 2)) |\
(0b11 << (PINOUT_LED_2 * 2)) |\
(0b11 << (PINOUT_LED_3 * 2)) |\
(0b11 << (PINOUT_LED_4 * 2)) |\
(0b11 << (PINOUT_BTN * 2)));
GPIOA->MODER &= ~((0b11 << (PINOUT_DISP_CLK * 2)) |\
(0b11 << (PINOUT_DISP_DIO * 2)) |\
(0b11 << (PINOUT_POT * 2)));
// set output mode register configuration bits
// 0b00 -> input mode (reset state)
// 0b01 -> general purpose output mode
// 0b10 -> alternate function mode
// 0b11 -> analog mode
GPIOB->MODER |= (0b01 << (PINOUT_LED_1 * 2)) |\
(0b01 << (PINOUT_LED_2 * 2)) |\
(0b01 << (PINOUT_LED_3 * 2)) |\
(0b01 << (PINOUT_LED_4 * 2)) |\
(0b00 << (PINOUT_BTN * 2));
GPIOA->MODER |= (0b01 << (PINOUT_DISP_CLK * 2)) |\
(0b01 << (PINOUT_DISP_DIO * 2)) |\
(0b11 << (PINOUT_POT * 2));
// pull-up resistor for button
GPIOB->PUPDR &= ~(0b11 << (PINOUT_BTN * 2));
GPIOB->PUPDR |= (0b01 << (PINOUT_BTN * 2));
// calirate ADC1
ADC1->CR |= ADC_CR_ADCAL;
while ((ADC1->CR & ADC_CR_ADCAL));
// enable ADC V_REFINT
ADC->CCR |= ADC_CCR_VREFEN;
// enable ADC1
ADC1->CR |= ADC_CR_ADEN;
}
/*
* This function drives led <num> of the I/O-shield. <num> should be the number
* of the LED to drive (0, 1, 2 or 3) and <on> should be an integer with value
* 0 or 1 which indicates if the LED should be turned on (1) or off (0).
*/
void ledWrite(int num, int on) {
GPIOB->ODR &= ~(1 << leds[num]);
GPIOB->ODR |= (on << leds[num]);
}
/*
* This function returns the status of the pushbutton of the I/O-shield.
* Return value 1 indicates that the button is currently pressed and return
* value 0 indicates that the button is currently not pressed.
*/
int buttonRead() {
return (GPIOB->IDR & (1 << PINOUT_BTN)) > 0;
}
/*
* Read potmeter value as analog value between 0 and 2^12 - 1
* TODO: increase measurement sensitivity
*/
unsigned int potRead() {
ADC1->CHSELR = (1 << PINOUT_POT);
ADC1->CR |= ADC_CR_ADSTART;
while (ADC1->CR & ADC_CR_ADSTART);
uint16_t result = ADC1->DR;
ADC1->CR |= ADC_CR_ADSTP;
return result;
}
void delay(int amount) {
for (int i = 0; i < 500 * amount; i++) asm("nop");
}
int mod(int a, int b) {
int m = a % b;
return m < 0 ? (b < 0) ? m - b : m + b : m;
}
int main() {
shieldConfig();
uint8_t reverse = 0;
uint8_t led = 0;
while (1) {
for(int j = 0; j < 4; j++) ledWrite(j, 0);
ledWrite(potRead(), 1);
continue;
reverse = buttonRead();
for(int j = 0; j < 4; j++) ledWrite(j, 0);
led = mod(led + ((2 * reverse) - 1), 4);
ledWrite(led, 1);
// ledWrite(3, (ADC1->ISR & ADC_ISR_ADRDY) == 0 ? 0 : 1);
delay(100 + 300 * potRead());
}
}
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