lm4f: Make miniblink example more readable, by defining RGB pins

Instead of setting and clearing RGB pins by PINx constants, define more readable
constants such as RGB_RED, and RGB_PORT.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

examples/lm4f/stellaris-ek-lm4f120xl/miniblink/miniblink.c

@@ -2,7 +2,7 @@
  * This file is part of the libopencm3 project.
  *
  * Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
- * Copyright (C) 2012 Alexandru Gagniuc <mr.nuke.me@gmail.com>
+ * Copyright (C) 2012-2013 Alexandru Gagniuc <mr.nuke.me@gmail.com>
  *
  * This library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -30,62 +30,70 @@
 #include <libopencm3/lm4f/systemcontrol.h>
 #include <libopencm3/lm4f/gpio.h>
 
-void gpio_setup(void)
-{
-	SYSCTL_RCGCGPIO |= 0x20; /* Enable GPIOF in run mode. */
-	const u32 outpins = ((1<<3) | (1<<2) | (1<<1));
+/* This is how the RGB LED is connected on the stellaris launchpad */
+#define RGB_PORT	GPIOF
+enum {
+	LED_R	= GPIO1,
+	LED_G	= GPIO3,
+	LED_B	= GPIO2,
+};
 
-	GPIO_DIR(GPIOF) |= outpins; /* Configure outputs. */
-	GPIO_DEN(GPIOF) |= outpins; /* Enable digital function on outputs. */
+/*
+ * GPIO setup:
+ * Enable the pins driving the RGB LED as outputs.
+ */
+static void gpio_setup(void)
+{
+	/*
+	 * Configure GPIOF
+	 * This port is used to control the RGB LED
+	 */
+	periph_clock_enable(RCC_GPIOF);
+	const u32 outpins = (LED_R | LED_G | LED_B);
+
+	GPIO_DIR(RGB_PORT) |= outpins; /* Configure outputs. */
+	GPIO_DEN(RGB_PORT) |= outpins; /* Enable digital function on outputs. */
 }
 
 #define FLASH_DELAY 800000
+static void delay(void)
+{
+	int i;
+	for (i = 0; i < FLASH_DELAY; i++)       /* Wait a bit. */
+		__asm__("nop");
+}
+
 int main(void)
 {
 	int i;
 
 	gpio_setup();
 
-	/* Blink STATUS LED (PF0) on the board. */
+	/* Blink each color of the RGB LED in order. */
 	while (1) {
 		/*
 		 * Flash the Red diode
 		 */
-		gpio_set(GPIOF, GPIO1);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
-
-		gpio_clear(GPIOF, GPIO1);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
+		gpio_set(RGB_PORT, LED_R);
+		delay(); /* Wait a bit. */
+		gpio_clear(RGB_PORT, LED_R);
+		delay(); /* Wait a bit. */
 
 		/*
 		 * Flash the Green diode
 		 */
-		gpio_set(GPIOF, GPIO3);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
-
-		gpio_clear(GPIOF, GPIO3);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
+		gpio_set(RGB_PORT, LED_G);
+		delay(); /* Wait a bit. */
+		gpio_clear(RGB_PORT, LED_G);
+		delay(); /* Wait a bit. */
 
 		/*
 		 * Flash the Blue diode
 		 */
-		gpio_set(GPIOF, GPIO2);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
-
-		gpio_clear(GPIOF, GPIO2);
-
-		for (i = 0; i < FLASH_DELAY; i++)	/* Wait a bit. */
-			__asm__("nop");
+		gpio_set(RGB_PORT, LED_B);
+		delay(); /* Wait a bit. */
+		gpio_clear(RGB_PORT, LED_B);
+		delay(); /* Wait a bit. */
 	}
 
 	return 0;