diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef-bl.dat
index df6cc807d7..ca62f80361 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef-bl.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef-bl.dat
@@ -1,5 +1,7 @@
 # hw definition file for processing by chibios_pins.py
 
+# Sierra RM3100 & Airspeed common hwdef
+
 # MCU class and specific type
 MCU STM32L431 STM32L431xx
 
@@ -18,44 +20,33 @@ env AP_PERIPH 1
 # crystal frequency
 OSCILLATOR_HZ 16000000
 
-# assume 256k flash part
+# Flash available
 FLASH_SIZE_KB 256
 
+# a fault LED
+PA15 LED_BOOTLOADER OUTPUT LOW # amber
+define HAL_LED_ON 1
+
 STDOUT_SERIAL SD1
 STDOUT_BAUDRATE 57600
 
 # order of UARTs
-SERIAL_ORDER USART1 USART2
-
-# a fault LED
-PB0 LED_BOOTLOADER OUTPUT LOW # blue
-define HAL_LED_ON 1
-
-PB14 LED_RED OUTPUT LOW GPIO(1)
+SERIAL_ORDER USART1
 
 # USART1
 PA9  USART1_TX USART1 SPEED_HIGH NODMA
-PA10 USART1_RX USART1 SPEED_HIGH NODMA
-
-# USART2
-PA2 USART2_TX USART2 SPEED_HIGH NODMA
-PA3 USART2_RX USART2 SPEED_HIGH NODMA
+PA10  USART1_RX USART1 SPEED_HIGH NODMA
 
 define HAL_USE_SERIAL TRUE
-
 define STM32_SERIAL_USE_USART1 TRUE
-define STM32_SERIAL_USE_USART2 TRUE
+define SERIAL_BUFFERS_SIZE 32
 
 define HAL_NO_GPIO_IRQ
-
-define SERIAL_BUFFERS_SIZE 32
 define HAL_USE_EMPTY_IO TRUE
 define PORT_INT_REQUIRED_STACK 64
 
-
 define DMA_RESERVE_SIZE 0
 
-
 MAIN_STACK 0x800
 PROCESS_STACK 0x800
 
@@ -64,8 +55,6 @@ define HAL_DISABLE_LOOP_DELAY
 # enable CAN support
 PA11 CAN1_RX CAN1
 PA12 CAN1_TX CAN1
-PC1 GPIO_CAN1_SILENT OUTPUT PUSHPULL SPEED_LOW LOW
-
 CAN_ORDER 1
 
 # debugger support
@@ -78,16 +67,7 @@ define BOOTLOADER_BAUDRATE 57600
 # use a small bootloader timeout
 define HAL_BOOTLOADER_TIMEOUT 1000
 
-
-
 define CAN_APP_NODE_NAME "org.ardupilot.Sierra-L431"
 
-# Enable the GPS voltage pin
-PC13 GPS_EN OUTPUT HIGH
-
-# Enable the sensor voltage pin
-PC12 SENSOR_EN OUTPUT HIGH
-
 # Add CS pins to ensure they are high in bootloader
-#PC6 MPU_CS CS
-PA8 BARO_CS CS
+PB12 MAG_CS CS
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef.dat
index 41dfd20e5e..6f941affc5 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Sierra-L431/hwdef.dat
@@ -1,4 +1,6 @@
-g# hw definition file for processing by chibios_pins.py
+# hw definition file for processing by chibios_pins.py
+
+# Sierra RM3100 & Airspeed common hwdef
 
 # MCU class and specific type
 MCU STM32L431 STM32L431xx
@@ -20,56 +22,47 @@ APJ_BOARD_ID 1050
 # setup build for a peripheral firmware
 env AP_PERIPH 1
 
-# enable watchdog
-
 # crystal frequency
 OSCILLATOR_HZ 16000000
 
-# assume the 256k flash part
+# Flash available
 FLASH_SIZE_KB 256
 
-# order of UARTs
-SERIAL_ORDER USART1 USART2
-
 define HAL_CAN_POOL_SIZE 6000
 
-#STDOUT_SERIAL SD1
-#STDOUT_BAUDRATE 57600
+# LEDs
+PA15 LED OUTPUT LOW GPIO(1)
 
-# USART1 Debug
-PA9 USART1_TX USART1 SPEED_HIGH
-PA10 USART1_RX USART1 SPEED_HIGH
+STDOUT_SERIAL SD1
+STDOUT_BAUDRATE 57600
 
-# USART2 M9N
-PA2 USART2_TX USART2 SPEED_HIGH
-PA3 USART2_RX USART2 SPEED_HIGH
+# order of UARTs
+SERIAL_ORDER USART1
 
-# LEDs
-PB0 LED OUTPUT LOW GPIO(1)
+# USART1
+PA9  USART1_TX USART1 SPEED_HIGH NODMA
+PA10  USART1_RX USART1 SPEED_HIGH NODMA
 
-# a fault LED
-# PB14 LED_FAULT OUTPUT LOW # red
+define HAL_USE_SERIAL TRUE
+define STM32_SERIAL_USE_USART1 TRUE
+define SERIAL_BUFFERS_SIZE 32
 
-# SPI1 bus for Baro
+# SPI1 bus for RM3100
 PA5 SPI1_SCK SPI1
 PA6 SPI1_MISO SPI1
 PA7 SPI1_MOSI SPI1
-PA8 BARO_CS CS
-
-SPIDEV dps310 SPI1 DEVID3 BARO_CS MODE3 5*MHZ 5*MHZ
-BARO DPS280 SPI:dps310
+PB12 MAG_CS CS
 
-#SPIDEV Invensensev2 SPI2 DEVID2 IMU_CS  MODE3  2*MHZ  8*MHZ
+# compass
+SPIDEV rm3100 SPI1 DEVID1    MAG_CS MODE0  1*MHZ  1*MHZ
+COMPASS RM3100 SPI:rm3100 false ROTATION_PITCH_180
 
-# QMC5883L
+# MS4525DO Airspeed
 PB6 I2C1_SCL I2C1
 PB7 I2C1_SDA I2C1
 
 I2C_ORDER I2C1
 
-# compass
-COMPASS QMC5883L I2C:0:0xd false ROTATION_PITCH_180_YAW_90
-
 # allow for reboot command for faster development
 define HAL_PERIPH_LISTEN_FOR_SERIAL_UART_REBOOT_CMD_PORT 0
 
@@ -78,11 +71,8 @@ PA13 JTMS-SWDIO SWD
 PA14 JTCK-SWCLK SWD
 
 define HAL_NO_GPIO_IRQ
-define SERIAL_BUFFERS_SIZE 512
-
 define DMA_RESERVE_SIZE 2048
 
-
 # stack for fast interrupts
 define PORT_INT_REQUIRED_STACK 64
 
@@ -97,40 +87,21 @@ define HAL_DISABLE_LOOP_DELAY
 # enable CAN support
 PA11 CAN1_RX CAN1
 PA12 CAN1_TX CAN1
-PC1 GPIO_CAN1_SILENT OUTPUT PUSHPULL SPEED_LOW LOW
-
 CAN_ORDER 1
 
 define HAL_USE_ADC TRUE
 define STM32_ADC_USE_ADC1 TRUE
-PA4 VSENSE ADC1 SCALE(2)
+PA0 VSENSE ADC1 SCALE(2)
 
 define HAL_GCS_ENABLED 0
 define HAL_NO_MONITOR_THREAD
 define HAL_NO_LOGGING
 define HAL_MINIMIZE_FEATURES 0
-
-
 define AP_PARAM_MAX_EMBEDDED_PARAM 512
 
-
-
-
 define CAN_APP_NODE_NAME "org.ardupilot.Sierra-L431"
 
-define HAL_PERIPH_ENABLE_GPS
-define HAL_PERIPH_GPS_PORT_DEFAULT 1
-
 define HAL_PERIPH_ENABLE_MAG
-define HAL_PERIPH_ENABLE_BARO
 define HAL_PERIPH_ENABLE_AIRSPEED
-
-#BARO MS56XX SPI:ms5611
-#BARO BMP388 I2C:0:0x76
-
-# define HAL_SPI_CHECK_CLOCK_FREQ
-
-# WS2812 LED
-PA15 TIM2_CH1 TIM2 PWM(1)
-PB11 TIM2_CH4 TIM2 PWM(2)
-
+define AIRSPEED_MAX_SENSORS 1
+define HAL_AIRSPEED_TYPE_DEFAULT 1