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-rw-r--r--examples/stm32/stm32-h103/usart/usart.c42
-rw-r--r--lib/stm32/usart.c19
2 files changed, 54 insertions, 7 deletions
diff --git a/examples/stm32/stm32-h103/usart/usart.c b/examples/stm32/stm32-h103/usart/usart.c
index 487ee84..9692d61 100644
--- a/examples/stm32/stm32-h103/usart/usart.c
+++ b/examples/stm32/stm32-h103/usart/usart.c
@@ -26,15 +26,45 @@ void clock_setup(void)
rcc_clock_setup_in_hse_8mhz_out_72mhz();
/* Enable GPIOC clock. */
- rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPCEN);
+ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPAEN | RCC_APB2ENR_IOPBEN | RCC_APB2ENR_IOPCEN);
/* Enable clocks for GPIO port B (for GPIO_USART3_TX) and USART3. */
- rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_IOPBEN);
- rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART3EN);
+ rcc_peripheral_enable_clock(&RCC_APB2ENR, RCC_APB2ENR_USART1EN);
+ rcc_peripheral_enable_clock(&RCC_APB1ENR, RCC_APB1ENR_USART2EN | RCC_APB1ENR_USART3EN);
}
void usart_setup(void)
{
+ /* Setup GPIO pin GPIO_USART1_TX. */
+ 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);
+ 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);
+
+ /* Setup GPIO pin GPIO_USART2_TX. */
+ gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ,
+ GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART2_TX);
+
+ /* Setup UART 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);
+
/* Setup GPIO pin GPIO_USART3_TX/GPIO10 on GPIO port B for transmit. */
gpio_set_mode(GPIOB, GPIO_MODE_OUTPUT_50_MHZ,
GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART3_TX);
@@ -69,9 +99,15 @@ int main(void)
/* Blink the LED (PC12) on the board with every transmitted byte. */
while (1) {
gpio_toggle(GPIOC, GPIO12); /* LED on/off */
+ usart_send_blocking(USART1, c + '0'); /* USART1: Send byte. */
+ usart_send_blocking(USART2, c + '0'); /* USART2: Send byte. */
usart_send_blocking(USART3, c + '0'); /* USART3: 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');
+ usart_send_blocking(USART2, '\r');
+ usart_send_blocking(USART2, '\n');
usart_send_blocking(USART3, '\r');
usart_send_blocking(USART3, '\n');
}
diff --git a/lib/stm32/usart.c b/lib/stm32/usart.c
index f644776..ead0ef7 100644
--- a/lib/stm32/usart.c
+++ b/lib/stm32/usart.c
@@ -17,14 +17,25 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <libopencm3/stm32/rcc.h>
+
#include <libopencm3/stm32/usart.h>
void usart_set_baudrate(u32 usart, u32 baud)
{
- u32 clock = 72000000; /* FIXME: Don't hardcode this clock! */
-
- /* TODO: Document and explain calculation. */
- USART_BRR(usart) = (u16)((clock << 4) / (baud * 16));
+ u32 clock = rcc_ppre1_frequency;
+
+ if (usart == USART1) {
+ clock = rcc_ppre2_frequency;
+ }
+
+ /* yes it is as simple as that. The reference manual is
+ * talking about factional calculation but it seems to be only
+ * marketting bable to sound awesome. It is nothing else but a
+ * simple divider to generate the correct baudrate. >_< If I
+ * am wrong feel free to correct me on that. :) (esden)
+ */
+ USART_BRR(usart) = clock/baud;
}
void usart_set_databits(u32 usart, u32 bits)