Usart baud rate setting function now uses the new apb1 and apb2 frequency variables. And calculates the full BRR value.

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');
 		}

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)