make USART more noise resistant

7 years ago · 875e0de18b
parent 765fb2e338
commit 875e0de18b
1 changed files with 2 additions and 1 deletions
--- a/lib/usart.c
+++ b/lib/usart.c
@ -44,7 +44,8 @@ void usart_setup(void)
 {
 	rcc_periph_clock_enable(USART_RCC); // enable USART1 clock
 	gpio_set_mode(USART_PORT, GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, USART_PIN_TX); // setup GPIO pin USART transmit
-	gpio_set_mode(USART_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, USART_PIN_RX); // setup GPIO pin USART receive
+	gpio_set_mode(USART_PORT, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, USART_PIN_RX); // setup GPIO pin USART receive
+	gpio_set(USART_PORT, USART_PIN_RX); // pull up to avoid noise when not connected

 	/* setup UART parameters */
 	usart_set_baudrate(USART, 115200);