diff --git a/src/drivers/boards/px4fmu-v4/board_config.h b/src/drivers/boards/px4fmu-v4/board_config.h
index f86d904aea..6d6e99b91b 100644
--- a/src/drivers/boards/px4fmu-v4/board_config.h
+++ b/src/drivers/boards/px4fmu-v4/board_config.h
@@ -236,10 +236,10 @@
 #define GPIO_OTGFS_VBUS		(GPIO_INPUT|GPIO_FLOAT|GPIO_SPEED_100MHz|GPIO_OPENDRAIN|GPIO_PORTA|GPIO_PIN9)
 
 /* High-resolution timer */
-#define HRT_TIMER		3	/* use timer8 for the HRT */
-#define HRT_TIMER_CHANNEL	4	/* use capture/compare channel */
+#define HRT_TIMER           3   /* use timer 3 for the HRT */
+#define HRT_TIMER_CHANNEL	4   /* use capture/compare channel 4 */
 
-#define HRT_PPM_CHANNEL		3	/* use capture/compare channel 2 */
+#define HRT_PPM_CHANNEL		3	/* use capture/compare channel 3 */
 #define GPIO_PPM_IN			(GPIO_ALT|GPIO_AF2|GPIO_PULLUP|GPIO_PORTB|GPIO_PIN0)
 
 #define RC_SERIAL_PORT		"/dev/ttyS4"
@@ -255,7 +255,7 @@
 #define GPIO_PERIPH_3V3_EN		(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN5)
 /* for R12, this signal is active high */
 #define GPIO_SBUS_INV			(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTC|GPIO_PIN13)
-#define INVERT_RC_INPUT(_s)		px4_arch_gpiowrite(GPIO_SBUS_INV, _s)
+#define INVERT_RC_INPUT(_invert_true) px4_arch_gpiowrite(GPIO_SBUS_INV, _invert_true)
 
 #define GPIO_8266_GPIO0			(GPIO_INPUT|GPIO_PULLUP|GPIO_PORTE|GPIO_PIN2)
 #define GPIO_SPEKTRUM_PWR_EN		(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_CLEAR|GPIO_PORTE|GPIO_PIN4)
@@ -264,14 +264,21 @@
 
 /* Power switch controls ******************************************************/
 
-#define POWER_SPEKTRUM(_s)			px4_arch_gpiowrite(GPIO_SPEKTRUM_PWR_EN, (1-_s))
-#define SPEKTRUM_RX_AS_UART()		px4_arch_configgpio(GPIO_USART1_RX)
+#define SPEKTRUM_POWER(_on_true)    px4_arch_gpiowrite(GPIO_SPEKTRUM_PWR_EN, (!_on_true))
 
-// FMUv4 has a separate GPIO for serial RC output
-#define GPIO_RC_OUT			(GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTB|GPIO_PIN0)
-#define SPEKTRUM_RX_AS_GPIO()		px4_arch_configgpio(GPIO_RC_OUT)
-#define SPEKTRUM_RX_HIGH(_s)		px4_arch_gpiowrite(GPIO_RC_OUT, (_s))
+/*
+ * FMUv4 has separate RC_IN
+ *
+ * GPIO PPM_IN on PB0 T3C3
+ * SPEKTRUM_RX (it's TX or RX in Bind) on UART6 PC7
+ * Inversion is possible via the 74LVC2G86 controlled by the FMU
+ * The FMU can drive  GPIO PPM_IN as an output
+ */
 
+#define GPIO_PPM_IN_AS_OUT             (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_SPEED_2MHz|GPIO_OUTPUT_SET|GPIO_PORTB|GPIO_PIN0)
+#define SPEKTRUM_RX_AS_GPIO_OUTPUT()   px4_arch_configgpio(GPIO_PPM_IN_AS_OUT)
+#define SPEKTRUM_RX_AS_UART()          /* Can be left as uart */
+#define SPEKTRUM_OUT(_one_true)        px4_arch_gpiowrite(GPIO_PPM_IN_AS_OUT, (_one_true))
 
 #define	BOARD_NAME "PX4FMU_V4"
 
diff --git a/src/drivers/boards/px4fmu-v4/px4fmu_init.c b/src/drivers/boards/px4fmu-v4/px4fmu_init.c
index c985808061..d3978990f4 100644
--- a/src/drivers/boards/px4fmu-v4/px4fmu_init.c
+++ b/src/drivers/boards/px4fmu-v4/px4fmu_init.c
@@ -182,11 +182,6 @@ stm32_boardinitialize(void)
 	stm32_configgpio(GPIO_8266_RST);
 	stm32_configgpio(GPIO_BTN_SAFETY);
 
-#ifdef GPIO_RC_OUT
-	stm32_configgpio(GPIO_RC_OUT);      /* Serial RC output pin */
-	stm32_gpiowrite(GPIO_RC_OUT, 1);    /* set it high to pull RC input up */
-#endif
-
 	/* configure the GPIO pins to outputs and keep them low */
 	stm32_configgpio(GPIO_GPIO0_OUTPUT);
 	stm32_configgpio(GPIO_GPIO1_OUTPUT);