diff --git a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
index c595075e0d..b7ebbee9e5 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
@@ -65,10 +65,13 @@ PB14 HEATER OUTPUT GPIO(0)
 PB5 SAFETY_INPUT INPUT PULLDOWN
 PB13 SAFETY_LED OUTPUT HIGH
 
+# amber LED
+PB15 AMBER_LED OUTPUT LOW
+
 # UART for DSM input
 # TX side is for IO debug, and is unused
 PA9  USART1_TX USART1
-PA10 USART1_RX USART1
+PA10 USART1_RX USART1 PULLUP
 
 PC13 SPEKTRUM_PWR_EN OUTPUT LOW
 define HAL_GPIO_PIN_SPEKTRUM_OUT PAL_LINE(GPIOA,10U)