light changes direction when button is down

1 files changed, 43 insertions, 18 deletions

diff --git a/src/main.c b/src/main.c
index dea5b7a..a357387 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,12 +1,21 @@
 #include "stm32f0xx.h"
 
-#define PINOUT_LED_1 3
-#define PINOUT_LED_2 5
-#define PINOUT_LED_3 4
-#define PINOUT_LED_4 6
+// 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,
@@ -14,18 +23,30 @@ const unsigned short leds[] = {PINOUT_LED_1, PINOUT_LED_2, PINOUT_LED_3, PINOUT_
  * GPIOx_PUPDR to configure pull-up and pull-down resistors.
  */
 void shieldConfig() {
-	// enable clock for I/O port D
+	// enable clock for I/O ports A and B
 	RCC->AHBENR |= RCC_AHBENR_GPIOBEN;
 
+	// 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_LED_4 * 2)) |\
+										(0b11 << (PINOUT_BTN * 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));
+	                (0b01 << (PINOUT_LED_4 * 2)) |\
+									(0b00 << (PINOUT_BTN * 2));
+
+	// pull-up resistor for button
+	GPIOB->PUPDR &= ~(0b11 << (PINOUT_BTN * 2));
+	GPIOB->PUPDR |=  (0b01 << (PINOUT_BTN * 2));
 }
 
 /*
@@ -44,7 +65,7 @@ void ledWrite(int num, int on) {
  * value 0 indicates that the button is currently not pressed.
  */
 int buttonRead() {
-	return 0;
+	return (GPIOB->IDR & (1 << PINOUT_BTN)) > 0;
 }
 
 void delay()
@@ -55,22 +76,26 @@ void delay()
 		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();
 
-	// RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
-	// GPIOA->MODER &= ~(1 << (PINOUT_LED_1 * 2 + 1));
-	// GPIOA->MODER |=  (1 << (PINOUT_LED_1 * 2));
-
-	// GPIOA_MODER &= ~(0 << (PINOUT_LED_1 * 2 + 1));
-
+	uint8_t reverse = 0;
+	uint8_t led = 0;
 	while (1)
 	{
-		for(int i = 0; i < 2 * 4; i++) {
-			ledWrite(i % 4, i >= 4);
+		reverse = buttonRead();
+		for(int j = 0; j < 4; j++) ledWrite(j, 0);
+
+		led = mod(led + ((2 * reverse) - 1), 4);
 
-			delay();
-		}
+		ledWrite(led, 1);
+		delay();
 	}
 }