diff --git a/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef-bl.dat
new file mode 100644
index 0000000000..9ddc9a026d
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef-bl.dat
@@ -0,0 +1,4 @@
+# hw definition file for processing by chibios_hwdef.py
+# for CUAVv5 bootloader
+
+include ../fmuv5/hwdef-bl.dat
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef.dat
new file mode 100644
index 0000000000..617155c018
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/CUAVv5/hwdef.dat
@@ -0,0 +1,4 @@
+# hw definition file for processing by chibios_hwdef.py
+# for CUAVv5 hardware.
+
+include ../fmuv5/hwdef.dat
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/PH4-mini/defaults.parm b/libraries/AP_HAL_ChibiOS/hwdef/PH4-mini/defaults.parm
new file mode 100644
index 0000000000..ccd4e2f888
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/PH4-mini/defaults.parm
@@ -0,0 +1,4 @@
+
+# Pixhawk4 does not have hw flow control on radios
+BRD_SER1_RTSCTS 0
+BRD_SER2_RTSCTS 0
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/defaults.parm b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/defaults.parm
new file mode 100644
index 0000000000..ccd4e2f888
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/defaults.parm
@@ -0,0 +1,4 @@
+
+# Pixhawk4 does not have hw flow control on radios
+BRD_SER1_RTSCTS 0
+BRD_SER2_RTSCTS 0
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef-bl.dat b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef-bl.dat
new file mode 100644
index 0000000000..8f84484e43
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef-bl.dat
@@ -0,0 +1,4 @@
+# hw definition file for processing by chibios_hwdef.py
+# for Pixhawk4 bootloader
+
+include ../fmuv5/hwdef-bl.dat
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef.dat
new file mode 100644
index 0000000000..e273b7fdc5
--- /dev/null
+++ b/libraries/AP_HAL_ChibiOS/hwdef/Pixhawk4/hwdef.dat
@@ -0,0 +1,5 @@
+# hw definition file for processing by chibios_hwdef.py
+# for Holybro Pixhawk4 hardware.
+
+include ../fmuv5/hwdef.dat
+