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authorPiotr Esden-Tempski2013-01-28 18:26:46 -0800
committerPiotr Esden-Tempski2013-01-29 13:33:58 -0800
commit8b062bb659a696e5d9ff910bc7d7c986c9b1151d (patch)
tree97f0e9f3c5ae483b3b8c3f2310bc2b13a7695b8c /examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c
parent20bfcaeb1c773012f1c41e004915b72f6abba352 (diff)
Added IRQ USART example for the f4 discovery board.
Diffstat (limited to 'examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c')
-rw-r--r--examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c115
1 files changed, 115 insertions, 0 deletions
diff --git a/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c b/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c
new file mode 100644
index 0000000..8e7aa7f
--- /dev/null
+++ b/examples/stm32/f4/stm32f4-discovery/usart_irq/usart_irq.c
@@ -0,0 +1,115 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ * Copyright (C) 2013 Piotr Esden-Tempski <piotr@esden.net>
+ *
+ * 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/f4/rcc.h>
+#include <libopencm3/stm32/f4/gpio.h>
+#include <libopencm3/stm32/usart.h>
+#include <libopencm3/cm3/nvic.h>
+
+void clock_setup(void)
+{
+ /* Enable GPIOD clock for LED & USARTs. */
+ rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPDEN);
+ rcc_peripheral_enable_clock(&RCC_AHB1ENR, RCC_AHB1ENR_IOPAEN);
+
+ /* Enable clocks for USART2. */
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN);
+}
+
+void usart_setup(void)
+{
+ /* Enable the USART2 interrupt. */
+ nvic_enable_irq(NVIC_USART2_IRQ);
+
+ /* Setup GPIO pins for USART2 transmit. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);
+
+ /* Setup GPIO pins for USART2 receive. */
+ gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO3);
+ gpio_set_output_options(GPIOA, GPIO_OTYPE_OD, GPIO_OSPEED_25MHZ, GPIO3);
+
+ /* Setup USART2 TX and RX pin as alternate function. */
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
+ gpio_set_af(GPIOA, GPIO_AF7, GPIO3);
+
+ /* 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_RX);
+ usart_set_parity(USART2, USART_PARITY_NONE);
+ usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);
+
+ /* Enable USART2 Receive interrupt. */
+ usart_enable_rx_interrupt(USART2);
+
+ /* Finally enable the USART. */
+ usart_enable(USART2);
+}
+
+void gpio_setup(void)
+{
+ /* Setup GPIO pin GPIO12 on GPIO port D for LED. */
+ gpio_mode_setup(GPIOD, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO12);
+}
+
+int main(void)
+{
+ clock_setup();
+ gpio_setup();
+ usart_setup();
+
+ while (1) {
+ __asm__("NOP");
+ }
+
+ return 0;
+}
+
+void usart2_isr(void)
+{
+ static u8 data = 'A';
+
+ /* Check if we were called because of RXNE. */
+ if (((USART_CR1(USART2) & USART_CR1_RXNEIE) != 0) &&
+ ((USART_SR(USART2) & USART_SR_RXNE) != 0)) {
+
+ /* Indicate that we got data. */
+ gpio_toggle(GPIOD, GPIO12);
+
+ /* Retrieve the data from the peripheral. */
+ data = usart_recv(USART2);
+
+ /* Enable transmit interrupt so it sends back the data. */
+ usart_enable_tx_interrupt(USART2);
+ }
+
+ /* Check if we were called because of TXE. */
+ if (((USART_CR1(USART2) & USART_CR1_TXEIE) != 0) &&
+ ((USART_SR(USART2) & USART_SR_TXE) != 0)) {
+
+ /* Put data into the transmit register. */
+ usart_send(USART2, data);
+
+ /* Disable the TXE interrupt as we don't need it anymore. */
+ usart_disable_tx_interrupt(USART2);
+ }
+}