Add usart support for L1.

Only tested with basic tx blocking, ie, the same example code as on
F2/F4, but the description of the block is almost identical.

examples/stm32/l1/stm32l-discovery/usart/Makefile

@@ -0,0 +1,25 @@
+##
+## This file is part of the libopencm3 project.
+##
+## Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## 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 = ../../../../../lib/stm32/l1/stm32l15xxb.ld
+
+include ../../Makefile.include
+

examples/stm32/l1/stm32l-discovery/usart/README

@@ -0,0 +1,12 @@
+------------------------------------------------------------------------------
+README
+------------------------------------------------------------------------------
+
+This example program sends some characters on USART2 on the
+ST STM32L DISCOVERY eval board. (USART2 TX on PA2)
+
+The terminal settings for the receiving device/PC are 38400 8n1.
+
+The sending is done in a blocking way in the code, see the usart_irq example
+for a more elaborate USART example.
+

examples/stm32/l1/stm32l-discovery/usart/usart.c

@@ -0,0 +1,80 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2012 Karl Palsson <karlp@tweak.net.au>
+ *
+ * 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/l1/rcc.h>
+#include <libopencm3/stm32/l1/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+void clock_setup(void) {
+    /* We are running on MSI after boot. */
+    /* Enable GPIOD clock for LED & USARTs. */
+    rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOAEN);
+    rcc_peripheral_enable_clock(&RCC_AHBENR, RCC_AHBENR_GPIOBEN);
+
+    /* Enable clocks for USART2. */
+    rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
+}
+
+void usart_setup(void) {
+    /* Setup USART2 parameters. */
+    usart_set_baudrate(USART2, 38400);
+    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);
+}
+
+void gpio_setup(void) {
+    /* Setup GPIO pin GPIO7 on GPIO port B for Green LED. */
+    gpio_mode_setup(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO7);
+
+    /* 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(GPIOB, GPIO7); /* 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 < 100000; i++) /* Wait a bit. */
+            __asm__("NOP");
+    }
+
+    return 0;
+}

include/libopencm3/stm32/l1/gpio.h

@@ -152,7 +152,7 @@
 #define GPIO_MODE_MASK(n)               (0x3 << (2 * (n)))
 #define GPIO_MODE_INPUT			0x00	/* Default */
 #define GPIO_MODE_OUTPUT		0x01
-#define GPIO_MODE_ALTFN			0x02
+#define GPIO_MODE_AF			0x02
 #define GPIO_MODE_ANALOG		0x03
 
 /* --- GPIOx_OTYPER values -------------------------------------------- */

lib/stm32/l1/Makefile

@@ -28,7 +28,7 @@ CFLAGS		= -Os -g -Wall -Wextra -I../../../include -fno-common \
 		  -ffunction-sections -fdata-sections -MD -DSTM32F1
 # ARFLAGS	= rcsv
 ARFLAGS		= rcs
-OBJS		= rcc.o gpio.o desig.o crc.o
+OBJS		= rcc.o gpio.o desig.o crc.o usart.o
 
 VPATH += ../../usb:../:../../cm3
 

lib/stm32/usart.c

@@ -46,6 +46,8 @@ LGPL License Terms @ref lgpl_license
 #	include <libopencm3/stm32/f2/rcc.h>
 #elif defined(STM32F4)
 #	include <libopencm3/stm32/f4/rcc.h>
+#elif defined(STM32L1)
+#	include <libopencm3/stm32/l1/rcc.h>
 #else
 #	error "stm32 family not defined."
 #endif