vf6xx: add GPIO example

This example muxes two pins as GPIO and enables one GPIO (logical
high). The other GPIO is then read in the main loop. One can use
a jumper to bridge the two GPIOs to see that also reading succeeds.

Author: agners

examples/vf6xx/colibri-vf61/gpio/Makefile

@@ -0,0 +1,26 @@
+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <[email protected]>
+## Copyright (C) 2014 Stefan Agner <[email protected]>
+##
+## 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
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This library is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU Lesser General Public License for more details.
+##
+## You should have received a copy of the GNU Lesser General Public License
+## along with this library.  If not, see <http://www.gnu.org/licenses/>.
+##
+
+BINARY = gpio
+
+LDSCRIPT = ../colibri-vf61.ld
+
+include ../Makefile.include
+

examples/vf6xx/colibri-vf61/gpio/gpio.c

@@ -0,0 +1,95 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <[email protected]>
+ * Copyright (C) 2014 Stefan Agner <[email protected]>
+ *
+ * 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
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <libopencm3/cm3/common.h>
+#include <libopencm3/vf6xx/ccm.h>
+#include <libopencm3/vf6xx/uart.h>
+#include <libopencm3/vf6xx/gpio.h>
+#include <libopencm3/vf6xx/iomuxc.h>
+
+
+static const uint32_t gpio_out = IOMUXC_PAD(MUX_MODE_ALT0, SPEED_LOW, \
+			DSE_150OHM, PUS_PU_100KOHM, IOMUXC_OBE | IOMUXC_IBE);
+
+static const uint32_t gpio_in = IOMUXC_PAD(MUX_MODE_ALT0, SPEED_LOW, \
+			DSE_150OHM, PUS_PU_100KOHM, IOMUXC_IBE);
+
+int _write(int file, char *ptr, int len);
+void sys_tick_handler(void);
+
+int _write(int file, char *ptr, int len)
+{
+	int i;
+
+	if (file == 1) {
+		for (i = 0; i < len; i++)
+			uart_send_blocking(UART2, ptr[i]);
+		return i;
+	}
+
+	errno = EIO;
+	return -1;
+}
+
+static void uart_init()
+{
+	ccm_clock_gate_enable(CG9_UART2);
+	uart_enable(UART2);
+	uart_set_baudrate(UART2, 115200);
+}
+
+int main(void)
+{
+	int old_state = -1;
+	int new_state = 0;
+
+
+	/* Init Clock Control and UART */
+	ccm_calculate_clocks();
+	uart_init();
+
+	/* Iris Carrier Board, X16, Pin 15 */
+	iomuxc_mux(PTC3, gpio_out);
+
+	/* Iris Carrier Board, X16, Pin 16 */
+	iomuxc_mux(PTC2, gpio_in);
+
+	gpio_set(PTC3);
+	printf("GPIO %d is %s\r\n", PTC3, gpio_get(PTC3) ? "high" : "low");
+
+	/*
+	 * Read input GPIO in a loop and print changes
+	 * A jumper between PTC3<=> PTC2 can be used to set PTC2 to high
+	 */
+	while (1) {
+		new_state = gpio_get(PTC2);
+		if (old_state != new_state) {
+			printf("GPIO %d is %s\r\n", PTC2,
+				new_state ? "high" : "low");
+			old_state = new_state;
+		}
+	}
+
+
+	return 0;
+}
+