diff --git a/libraries/AP_HAL_ChibiOS/hwdef/DrotekP3Pro/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/DrotekP3Pro/hwdef.dat
index 0de79a8191..fbd4c04ea9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/DrotekP3Pro/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/DrotekP3Pro/hwdef.dat
@@ -74,7 +74,6 @@ PE15 MAG_CS CS
 PH5 EEPROM_CS CS
 
 PA9 VBUS INPUT OPENDRAIN
-PA10 FRSKY_INV OUTPUT GPIO(78)
 
 # now we define the pins that USB is connected on
 PA11 OTG_FS_DM OTG1
@@ -172,6 +171,11 @@ PD15 MPU9250_DRDY INPUT
 # UART8 serial4 FrSky
 PE0 UART8_RX UART8
 PE1 UART8_TX UART8
+# allow this uart to be inverted for transmit under user control
+# the polarity is the value to use on the GPIO to change the polarity
+# to the opposite of the default
+PA10 UART8_TXINV OUTPUT HIGH GPIO(78) POL(0)
+
 PE3 VDD_SENSORS_EN OUTPUT HIGH
 
 # start peripheral power off, then enable after init
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/mindpx-v2/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/mindpx-v2/hwdef.dat
index 110962447f..4cb1084156 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/mindpx-v2/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/mindpx-v2/hwdef.dat
@@ -99,8 +99,6 @@ PB9 I2C1_SDA I2C1
 PB10 I2C2_SCL I2C2
 PB11 I2C2_SDA I2C2
 
-PB12 FRSKY_INV OUTPUT
-
 # SPI2 is external SPI (radio NRF)
 PB13 SPI2_SCK SPI2
 PB14 SPI2_MISO SPI2
@@ -146,6 +144,11 @@ PD11 ACCEL_MAG_CS CS
 PE0 UART8_RX UART8
 PE1 UART8_TX UART8
 
+# allow this uart to be inverted for transmit under user control
+# the polarity is the value to use on the GPIO to change the polarity
+# to the opposite of the default
+PB12 UART8_TXINV OUTPUT HIGH GPIO(78) POL(0)
+
 # SPI4 is M_SPI (main sensors)
 PE2 SPI4_SCK SPI4
 PE3 MPU_CS CS