diff --git a/flight/PiOS/Common/pios_gcsrcvr.c b/flight/PiOS/Common/pios_gcsrcvr.c
index e3e34db5b..709eeef76 100644
--- a/flight/PiOS/Common/pios_gcsrcvr.c
+++ b/flight/PiOS/Common/pios_gcsrcvr.c
@@ -137,11 +137,18 @@ extern int32_t PIOS_GCSRCVR_Init(uint32_t *gcsrcvr_id)
 	return 0;
 }
 
+/**
+ * Get the value of an input channel
+ * \param[in] channel Number of the channel desired (zero based)
+ * \output PIOS_RCVR_INVALID channel not available
+ * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
+ * \output >=0 channel value
+ */
 static int32_t PIOS_GCSRCVR_Get(uint32_t rcvr_id, uint8_t channel)
 {
 	if (channel >= GCSRECEIVER_CHANNEL_NUMELEM) {
 		/* channel is out of range */
-		return -1;
+		return PIOS_RCVR_INVALID;
 	}
 
 	return (gcsreceiverdata.Channel[channel]);
diff --git a/flight/PiOS/STM32F10x/pios_ppm.c b/flight/PiOS/STM32F10x/pios_ppm.c
index b47a2d6c2..4893d56a9 100644
--- a/flight/PiOS/STM32F10x/pios_ppm.c
+++ b/flight/PiOS/STM32F10x/pios_ppm.c
@@ -200,11 +200,12 @@ out_fail:
 }
 
 /**
-* Get the value of an input channel
-* \param[in] Channel Number of the channel desired
-* \output -1 Channel not available
-* \output >0 Channel value
-*/
+ * Get the value of an input channel
+ * \param[in] channel Number of the channel desired (zero based)
+ * \output PIOS_RCVR_INVALID channel not available
+ * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
+ * \output >=0 channel value
+ */
 static int32_t PIOS_PPM_Get(uint32_t rcvr_id, uint8_t channel)
 {
 	struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)rcvr_id;
diff --git a/flight/PiOS/STM32F10x/pios_pwm.c b/flight/PiOS/STM32F10x/pios_pwm.c
index 4e7c98b14..497a5d19b 100644
--- a/flight/PiOS/STM32F10x/pios_pwm.c
+++ b/flight/PiOS/STM32F10x/pios_pwm.c
@@ -170,11 +170,12 @@ out_fail:
 }
 
 /**
-* Get the value of an input channel
-* \param[in] Channel Number of the channel desired
-* \output -1 Channel not available
-* \output >0 Channel value
-*/
+ * Get the value of an input channel
+ * \param[in] channel Number of the channel desired (zero based)
+ * \output PIOS_RCVR_INVALID channel not available
+ * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
+ * \output >=0 channel value
+ */
 static int32_t PIOS_PWM_Get(uint32_t rcvr_id, uint8_t channel)
 {
 	struct pios_pwm_dev * pwm_dev = (struct pios_pwm_dev *)rcvr_id;
diff --git a/flight/PiOS/STM32F10x/pios_sbus.c b/flight/PiOS/STM32F10x/pios_sbus.c
index 53730b16b..50d0480c3 100644
--- a/flight/PiOS/STM32F10x/pios_sbus.c
+++ b/flight/PiOS/STM32F10x/pios_sbus.c
@@ -166,7 +166,7 @@ out_fail:
  * \param[in] channel Number of the channel desired (zero based)
  * \output PIOS_RCVR_INVALID channel not available
  * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
- * \output >0 channel value
+ * \output >=0 channel value
  */
 static int32_t PIOS_SBus_Get(uint32_t rcvr_id, uint8_t channel)
 {
diff --git a/flight/PiOS/STM32F4xx/pios_ppm.c b/flight/PiOS/STM32F4xx/pios_ppm.c
index 048377ebd..9acaca017 100644
--- a/flight/PiOS/STM32F4xx/pios_ppm.c
+++ b/flight/PiOS/STM32F4xx/pios_ppm.c
@@ -200,11 +200,12 @@ out_fail:
 }
 
 /**
-* Get the value of an input channel
-* \param[in] Channel Number of the channel desired
-* \output -1 Channel not available
-* \output >0 Channel value
-*/
+ * Get the value of an input channel
+ * \param[in] channel Number of the channel desired (zero based)
+ * \output PIOS_RCVR_INVALID channel not available
+ * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
+ * \output >=0 channel value
+ */
 static int32_t PIOS_PPM_Get(uint32_t rcvr_id, uint8_t channel)
 {
 	struct pios_ppm_dev * ppm_dev = (struct pios_ppm_dev *)rcvr_id;
diff --git a/flight/PiOS/STM32F4xx/pios_pwm.c b/flight/PiOS/STM32F4xx/pios_pwm.c
index 5bbec32aa..2c67ad465 100644
--- a/flight/PiOS/STM32F4xx/pios_pwm.c
+++ b/flight/PiOS/STM32F4xx/pios_pwm.c
@@ -170,11 +170,12 @@ out_fail:
 }
 
 /**
-* Get the value of an input channel
-* \param[in] Channel Number of the channel desired
-* \output -1 Channel not available
-* \output >0 Channel value
-*/
+ * Get the value of an input channel
+ * \param[in] channel Number of the channel desired (zero based)
+ * \output PIOS_RCVR_INVALID channel not available
+ * \output PIOS_RCVR_TIMEOUT failsafe condition or missing receiver
+ * \output >=0 channel value
+ */
 static int32_t PIOS_PWM_Get(uint32_t rcvr_id, uint8_t channel)
 {
 	struct pios_pwm_dev * pwm_dev = (struct pios_pwm_dev *)rcvr_id;