serial support

1 files changed, 27 insertions, 0 deletions

diff --git a/src/serial.c b/src/serial.c
new file mode 100644
index 0000000..692faf0
--- /dev/null
+++ b/src/serial.c
@@ -0,0 +1,27 @@
+#include <stm32l476xx.h>
+#include <gpio.h>
+
+void serial_init(void)
+{
+	gpio_mode(GPIOA, 2, ALTERNATE);
+	gpio_mode(GPIOA, 3, ALTERNATE);
+	GPIOA->AFR[0] &= ~(0x0000FF00);
+	GPIOA->AFR[0] |= 0x00007700;
+	RCC->APB1ENR1 |= RCC_APB1ENR1_USART2EN;
+
+	// start usart device
+	USART2->BRR = 80000000L / 115200L;
+	USART2->CR1 |= USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;
+}
+
+void serial_put(int c)
+{
+	while (!(USART2->ISR & USART_ISR_TXE));
+	USART2->TDR = c & 0xFF;
+}
+
+char serial_get(void)
+{
+	while (!(USART2->ISR & USART_ISR_RXNE));
+	return USART2->RDR & 0xFF;
+}