[wip?] progress

working:
- blocking interrupt function
- interrupt config
- shield config
- potread, buttonread, etc.

not working:
- interrupts

1 files changed, 165 insertions, 2 deletions

diff --git a/src/main.c b/src/main.c
index 4726e5e..241f369 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,11 +1,174 @@
-#define PINOUT_BTN (8)
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "stm32f091xc.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)
+
+volatile bool led_direction = false;
+
+/*
+ * 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 shield_config() {
+	// enable internal clocks
+	RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN; // GPIO A and B
+	RCC->APB2ENR |= RCC_APB2ENR_ADC1EN; // ADC1 peripheral
+	RCC->APB1ENR |= RCC_APB1ENR_TIM3EN; // TIM3
+
+	// 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);
+  ADC1->CR |= ADC_CR_ADEN; // enable ADC1
+
+	// TIM3 setup
+	TIM3->PSC = 8000 - 1; // prescaler set so each timer tick is 1ms
+	TIM3->CCMR1 |= TIM_CCMR1_OC1M_0;
+	TIM3->EGR |= TIM_EGR_UG; // generate update event 
+	TIM3->CR1 |= TIM_CR1_CEN; // enable counter
+}
+
+
+void toggle_direction() {
+	led_direction = !led_direction;
+}
+
+void EXTI4_15_IRQHandler(void) {
+	// toggle_direction();
+	led_direction = !led_direction;
+	return;
+}
+
+void interrupt_setup() {
+	RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN;
+	// RCC->APB2ENR |= RCC_APB2ENR_SYSCFGCOMPEN;
+	SYSCFG->EXTICR[PINOUT_BTN / 4] &= ~(0xF << ((PINOUT_BTN % 4) * 4));
+	SYSCFG->EXTICR[PINOUT_BTN / 4] |=  (0x1 << ((PINOUT_BTN % 4) * 4));
+
+	EXTI->IMR  |=  (1 << PINOUT_BTN);
+	EXTI->RTSR &= ~(1 << PINOUT_BTN);
+	EXTI->FTSR |=  (1 << PINOUT_BTN);
+
+	NVIC_SetPriority(EXTI4_15_IRQn, 3);
+	NVIC_EnableIRQ(EXTI4_15_IRQn);
+}
+
+/*
+ * 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 led_write(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 button_read() {
+	return (GPIOB->IDR & (1 << PINOUT_BTN)) == 0;
+}
+
+/*
+ * Read potmeter value as analog value between 0 and 2^12 - 1
+ */
+unsigned int pot_read() {
+	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 next_led() {
+	static uint8_t led = 0;
+	for(int j = 0; j < 4; j++) led_write(j, 0); // clear all leds
+	led = (led + led_direction * 2 - 1) & 0b11; // calculate next led index
+	led_write(led, 1);
+}
+
+void dumb_delay() {
+	for(unsigned long i = 0; i < 50e3; i++);
+}
+
+/**
+ * This function uses timer 3 to generate a blocking delay of <milliseconds>.
+ * It uses the channel 1 capture/compare register to check if the time (in
+ * milliseconds) has expired. 
+ */
+int timer_delay(unsigned short millis) {
+	TIM3->CCR1 = millis; // set delay amount
+	TIM3->CNT = 0; // reset timer
+	TIM3->SR &= ~(TIM_SR_CC1IF); // reset capture/compare output
+	while ((TIM3->SR & TIM_SR_CC1IF) == 0); // wait until c/c goes high
+}
+
 int main() {
-	return 0;
+	shield_config(); 
+	interrupt_setup();
+
+	while (1) {
+		// if ((TIM3->SR & TIM_SR_CC1IF) > 0) {
+		// 	toggle_direction();
+		// 	TIM3->CNT = 0;
+		// 	TIM3->SR &= ~(TIM_SR_CC1IF);
+		// 	TIM3->EGR |= TIM_EGR_UG;
+		// }
+		timer_delay(100);
+		next_led();
+	}
+}
+
+#ifdef __cplusplus
 }
+#endif