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Diffstat (limited to 'examples/stm32/f1/stm32-discovery/usart/usart.c')
-rw-r--r--examples/stm32/f1/stm32-discovery/usart/usart.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/examples/stm32/f1/stm32-discovery/usart/usart.c b/examples/stm32/f1/stm32-discovery/usart/usart.c
new file mode 100644
index 0000000..942805b
--- /dev/null
+++ b/examples/stm32/f1/stm32-discovery/usart/usart.c
@@ -0,0 +1,87 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <libopencm3/stm32/f1/rcc.h>
+#include <libopencm3/stm32/f1/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+void clock_setup(void)
+{
+ rcc_clock_setup_in_hse_8mhz_out_24mhz();
+
+ /* Enable GPIOC clock. */
+ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPCEN);
+
+ /* Enable clocks for GPIO port A (for GPIO_USART1_TX) and USART1. */
+ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN);
+ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_USART1EN);
+}
+
+void usart_setup(void)
+{
+ /* Setup GPIO pin GPIO_USART1_TX/GPIO9 on GPIO port A for transmit. */
+ gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
+ GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
+
+ /* Setup UART parameters. */
+ // usart_set_baudrate(USART1, 38400);
+ /* TODO usart_set_baudrate() doesn't support 24MHz clock (yet). */
+ /* This is the equivalent: */
+ USART_BRR(USART1) = (u16)((24000000 << 4) / (38400 * 16));
+
+ usart_set_databits(USART1, 8);
+ usart_set_stopbits(USART1, USART_STOPBITS_1);
+ usart_set_mode(USART1, USART_MODE_TX);
+ usart_set_parity(USART1, USART_PARITY_NONE);
+ usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
+
+ /* Finally enable the USART. */
+ usart_enable(USART1);
+}
+
+void gpio_setup(void)
+{
+ /* Set GPIO9 (in GPIO port C) to 'output push-pull'. [LED] */
+ gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ,
+ GPIO_CNF_OUTPUT_PUSHPULL, GPIO9);
+}
+
+int main(void)
+{
+ int i, j = 0, c = 0;
+
+ clock_setup();
+ gpio_setup();
+ usart_setup();
+
+ /* Blink the LED (PC9) on the board with every transmitted byte. */
+ while (1) {
+ gpio_toggle(GPIOC, GPIO9); /* LED on/off */
+ usart_send_blocking(USART1, c + '0'); /* USART1: Send byte. */
+ c = (c == 9) ? 0 : c + 1; /* Increment c. */
+ if ((j++ % 80) == 0) { /* Newline after line full. */
+ usart_send_blocking(USART1, '\r');
+ usart_send_blocking(USART1, '\n');
+ }
+ for (i = 0; i < 800000; i++) /* Wait a bit. */
+ __asm__("NOP");
+ }
+
+ return 0;
+}