Nucleo F411RE - Simple USART example

Same as the one for other boards

Author: ChuckM

examples/stm32/f4/nucleo-f411re/usart/Makefile

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+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <[email protected]>
+## Copyright (C) 2015 Chuck McManis <[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 = usart
+
+LDSCRIPT = ../nucleo-f411re.ld
+
+include ../../Makefile.include
+

examples/stm32/f4/nucleo-f411re/usart/README.md

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+# README
+
+This example program sends repeating sequence of characters "0123456789" on 
+USART2 on the ST Nucleo F411RE eval board.
+
+The sending is done in a blocking way.
+
+Note that the Nucleo board exports the serial port as an ttyACM device on
+Linux or a COM port on Windows. On Linux, if you can locate the correct
+serial port as 
+
+/dev/serial/by-id/usb-STMicroelectronics_STM32_STLink_066CFF515056805087171825-if02
+
+(note there will be differences based on the serial number of your board) 
+this may also show up as /dev/ttyACM0 if it was the first serial port 
+enumerated, if you have additional serial devices attached to the USB port
+of your system they may show up as additional ttyACM1/ttyACM2/... etc. 
+
+Connect to the port using `screen /dev/ttyACM0 115200` where you replace
+the serial port with the one for your system. 
+

examples/stm32/f4/nucleo-f411re/usart/usart.c

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <[email protected]>
+ * Copyright (C) 2011 Stephen Caudle <[email protected]>
+ * Copyright (C) 2015 Chuck McManis <[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 <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+static void clock_setup(void)
+{
+	/* Enable GPIOD clock for LED & USARTs. */
+	rcc_periph_clock_enable(RCC_GPIOA);
+
+	/* Enable clocks for USART2. */
+	rcc_periph_clock_enable(RCC_USART2);
+}
+
+static void usart_setup(void)
+{
+	/* Setup USART2 parameters. */
+	usart_set_baudrate(USART2, 115200);
+	usart_set_databits(USART2, 8);
+	usart_set_stopbits(USART2, USART_STOPBITS_1);
+	usart_set_mode(USART2, USART_MODE_TX);
+	usart_set_parity(USART2, USART_PARITY_NONE);
+	usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+
+	/* Finally enable the USART. */
+	usart_enable(USART2);
+}
+
+static void gpio_setup(void)
+{
+	/* Setup GPIO pin GPIO5 on GPIO port A for LED. */
+	gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO5);
+
+	/* Setup GPIO pins for USART2 transmit. */
+	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+
+	/* Setup USART2 TX pin as alternate function. */
+	gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+}
+
+int main(void)
+{
+	int i, j = 0, c = 0;
+
+	clock_setup();
+	gpio_setup();
+	usart_setup();
+
+	/* Blink the LED (PD12) on the board with every transmitted byte. */
+	while (1) {
+		gpio_toggle(GPIOA, GPIO5);	/* LED on/off */
+		usart_send_blocking(USART2, c + '0'); /* USART2: Send byte. */
+		c = (c == 9) ? 0 : c + 1;	/* Increment c. */
+		if ((j++ % 80) == 0) {		/* Newline after line full. */
+			usart_send_blocking(USART2, '\r');
+			usart_send_blocking(USART2, '\n');
+		}
+		for (i = 0; i < 300000; i++) {	/* Wait a bit. */
+			__asm__("NOP");
+		}
+	}
+
+	return 0;
+}