[stm32f429i-discovery] Moved Chucks example to usart_console

Chucks example is more elaborate than the simple ported example so we
keep both.

examples/stm32/f4/stm32f429i-discovery/usart_console/Makefile

@@ -0,0 +1,25 @@
+#
+# This file is part of the libopencm3 project.
+#
+# 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/>.
+#
+
+OBJS = clock.o
+
+BINARY = usart_console
+
+LDSCRIPT = ../stm32f429i-discovery.ld
+
+include ../../Makefile.include
+

examples/stm32/f4/stm32f429i-discovery/usart_console/README

@@ -0,0 +1,9 @@
+Simple USART Example
+--------------------
+
+This example sets up a USART port and provides a few simple
+character handling functions to that a short interactive program
+can be demonstrated. It re-uses the clock setup from systick_blink
+and that means you could do times delays but that aspect isn't used.
+
+After this example we do character handling with interrupts.

examples/stm32/f4/stm32f429i-discovery/usart_console/clock.c

@@ -0,0 +1,71 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.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
+ * 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/>.
+ */
+
+/*
+ * Now this is just the clock setup code from systick-blink as it is the
+ * transferrable part.
+ */
+
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/systick.h>
+
+/* Common function descriptions */
+#include "clock.h"
+
+/* milliseconds since boot */
+static volatile uint32_t system_millis;
+
+/* Called when systick fires */
+void sys_tick_handler(void) {
+	system_millis++;
+}
+
+/* simple sleep for delay milliseconds */
+void msleep(uint32_t delay) {
+	uint32_t wake = system_millis + delay;
+	while (wake > system_millis) ;
+}
+
+/* Getter function for the current time */
+uint32_t mtime(void) {
+	return system_millis;
+}
+
+/*
+ * clock_setup(void)
+ *
+ * This function sets up both the base board clock rate
+ * and a 1khz "system tick" count. The SYSTICK counter is
+ * a standard feature of the Cortex-M series.
+ */
+void clock_setup(void)
+{
+	/* Base board frequency, set to 168Mhz */
+	rcc_clock_setup_hse_3v3(&hse_8mhz_3v3[CLOCK_3V3_168MHZ]);
+
+	/* clock rate / 168000 to get 1mS interrupt rate */
+	systick_set_reload(168000);
+	systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
+	systick_counter_enable();
+
+	/* this done last */
+	systick_interrupt_enable();
+}

examples/stm32/f4/stm32f429i-discovery/usart_console/clock.h

@@ -0,0 +1,15 @@
+/*
+ * This include file describes the functions exported by clock.c
+ */
+#ifndef __CLOCK_H
+#define __CLOCK_H
+
+/*
+ * Definitions for functions being abstracted out
+ */
+void msleep(uint32_t);
+uint32_t mtime(void);
+void clock_setup(void);
+
+#endif /* generic header protector */
+

examples/stm32/f4/stm32f429i-discovery/usart_console/usart_console.c

@@ -0,0 +1,184 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2013 Chuck McManis <cmcmanis@mcmanis.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
+ * 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/>.
+ */
+
+/*
+ * USART example (alternate console)
+ */
+
+#include <stdint.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/usart.h>
+#include "clock.h"
+
+/*
+ * Some definitions of our console "functions" attached to the
+ * USART.
+ *
+ * These define sort of the minimum "library" of functions which
+ * we can use on a serial port. 
+ */
+
+#define CONSOLE_UART	USART2
+
+void console_putc(char c);
+char console_getc(int wait);
+void console_puts(char *s);
+int console_gets(char *s, int len);
+
+/*
+ * console_putc(char c)
+ *
+ * Send the character 'c' to the USART, wait for the USART
+ * transmit buffer to be empty first.
+ */
+void console_putc(char c) {
+	uint32_t	reg;
+	do {
+		reg = USART_SR(CONSOLE_UART);
+	} while ((reg & USART_SR_TXE) == 0);
+	USART_DR(CONSOLE_UART) = (uint16_t) c & 0xff;
+}
+
+/*
+ * char = console_getc(int wait)
+ *
+ * Check the console for a character. If the wait flag is
+ * non-zero. Continue checking until a character is received
+ * otherwise return 0 if called and no character was available.
+ */
+char console_getc(int wait) {
+	uint32_t	reg;
+	do {
+		reg = USART_SR(CONSOLE_UART);
+	} while ((wait != 0) && ((reg & USART_SR_RXNE) == 0));
+	return (reg & USART_SR_RXNE) ? USART_DR(CONSOLE_UART) : '\000';
+}
+
+/*
+ * void console_puts(char *s)
+ *
+ * Send a string to the console, one character at a time, return
+ * after the last character, as indicated by a NUL character, is
+ * reached.
+ */
+void console_puts(char *s) {
+	while (*s != '\000') {
+		console_putc(*s);
+		/* Add in a carraige return, after sending line feed */
+		if (*s == '\n') {
+			console_putc('\r');
+		}
+		s++;
+	}
+}
+
+/*
+ * int console_gets(char *s, int len)
+ *
+ * Wait for a string to be entered on the console, limited
+ * support for editing characters (back space and delete)
+ * end when a <CR> character is received.
+ */
+int console_gets(char *s, int len) {
+	char *t = s;
+	char c;
+
+	*t = '\000';
+	/* read until a <CR> is received */
+	while ((c = console_getc(1)) != '\r') {
+		if ((c == '\010') || (c == '\127')) {
+			if (t > s) {
+				/* send ^H ^H to erase previous character */
+				console_puts("\010 \010");
+				t--;
+			}
+		} else {
+			*t = c;
+			console_putc(c);
+			if ((t - s) < len) {
+				t++;
+			}
+		}
+		/* update end of string with NUL */
+		*t = '\000';
+	}
+	return (t - s);
+}
+
+/*
+ * Set up the GPIO subsystem with an "Alternate Function"
+ * on some of the pins, in this case connected to a
+ * USART.
+ */
+int main(void) {
+	char buf[128];
+	int	len;
+
+	clock_setup(); // initialize our clock
+
+	/* MUST enable the GPIO clock in ADDITION to the USART clock */
+	rcc_periph_clock_enable(RCC_GPIOD);
+
+	/* This example uses PD5 and PD6 for Tx and Rx respectively
+     * but other pins are available for this role on USART2 (our chosen
+ 	 * USART) as well, such as PA2 and PA3. You can also split them
+	 * so PA2 for Tx, PD6 for Rx but you would have to enable both
+	 * the GPIOA and GPIOD clocks in that case
+	 */
+	gpio_mode_setup(GPIOD, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO5 | GPIO6);
+
+	/* Actual Alternate function number (in this case 7) is part
+	 * depenedent, check the data sheet for the right number to
+	 * use.
+	 */
+	gpio_set_af(GPIOD, GPIO_AF7, GPIO5 | GPIO6);
+
+	/* This then enables the clock to the USART2 peripheral which is
+	 * attached inside the chip to the APB2 bus. Different peripherals
+	 * attach to different buses, and even some UARTS are attached to
+	 * APB1 and some to APB2, again the data sheet is useful here.
+	 */
+	rcc_periph_clock_enable(RCC_USART2);
+
+	/* Set up USART/UART parameters using the libopencm3 helper functions */
+	usart_set_baudrate(CONSOLE_UART, 115200);
+	usart_set_databits(CONSOLE_UART, 8);
+	usart_set_stopbits(CONSOLE_UART, USART_STOPBITS_1);
+	usart_set_mode(CONSOLE_UART, USART_MODE_TX_RX);
+	usart_set_parity(CONSOLE_UART, USART_PARITY_NONE);
+	usart_set_flow_control(CONSOLE_UART, USART_FLOWCONTROL_NONE);
+	usart_enable(CONSOLE_UART);
+
+	/* At this point our console is ready to go so we can create our
+	 * simple application to run on it.
+	 */
+	console_puts("\nUART Demonstration Application\n");
+	while (1) {
+		console_puts("Enter a string: ");
+		len = console_gets(buf, 128);
+		if (len) {
+			console_puts("\nYou entered : '");
+			console_puts(buf);
+			console_puts("'\n");
+		} else {
+			console_puts("\nNo string entered\n");
+		}
+	}
+}