From c0c0b8c976856c7e06b06efcf0e4c675d69c1356 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Wed, 22 Aug 2012 13:33:12 +1000
Subject: [PATCH] APM: added RECEIVER_RSSI_PIN option

this allows for the receiver RSSI to be sent over MAVLink

Thanks to Burt Green for the suggestion
---
 ArduPlane/ArduPlane.pde   |  4 ++++
 ArduPlane/GCS_Mavlink.pde |  3 +--
 ArduPlane/config.h        |  5 +++++
 ArduPlane/sensors.pde     | 15 +++++++++++++++
 4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/ArduPlane/ArduPlane.pde b/ArduPlane/ArduPlane.pde
index 0c078ae6f9..37c6012e24 100644
--- a/ArduPlane/ArduPlane.pde
+++ b/ArduPlane/ArduPlane.pde
@@ -280,6 +280,10 @@ AP_RangeFinder_MaxsonarXL sonar(&pitot_analog_source, &sonar_mode_filter);
 AP_RangeFinder_MaxsonarXL sonar(&pitot_analog_source, &sonar_mode_filter);
 #endif
 
+#if RECEIVER_RSSI_PIN != -1
+AP_AnalogSource_Arduino RSSI_pin(RECEIVER_RSSI_PIN, 0.25);
+#endif
+
 AP_Relay relay;
 
 
diff --git a/ArduPlane/GCS_Mavlink.pde b/ArduPlane/GCS_Mavlink.pde
index 2fe7b21e32..dddd6a5547 100644
--- a/ArduPlane/GCS_Mavlink.pde
+++ b/ArduPlane/GCS_Mavlink.pde
@@ -286,7 +286,6 @@ static void NOINLINE send_gps_raw(mavlink_channel_t chan)
 
 static void NOINLINE send_servo_out(mavlink_channel_t chan)
 {
-    const uint8_t rssi = 1;
     // normalized values scaled to -10000 to 10000
     // This is used for HIL.  Do not change without discussing with
     // HIL maintainers
@@ -302,7 +301,7 @@ static void NOINLINE send_servo_out(mavlink_channel_t chan)
         0,
         0,
         0,
-        rssi);
+        receiver_rssi());
 }
 
 static void NOINLINE send_radio_in(mavlink_channel_t chan)
diff --git a/ArduPlane/config.h b/ArduPlane/config.h
index 8f520da743..525e30ef9e 100644
--- a/ArduPlane/config.h
+++ b/ArduPlane/config.h
@@ -115,6 +115,11 @@
 #endif
 
 
+// pin for receiver RSSI
+#ifndef RECEIVER_RSSI_PIN
+# define RECEIVER_RSSI_PIN -1
+#endif
+
 //////////////////////////////////////////////////////////////////////////////
 // IMU Selection
 //
diff --git a/ArduPlane/sensors.pde b/ArduPlane/sensors.pde
index 1d7ca777c4..c77b22ade6 100644
--- a/ArduPlane/sensors.pde
+++ b/ArduPlane/sensors.pde
@@ -55,3 +55,18 @@ static void read_battery(void)
 #endif
 }
 
+
+// return receiver RSSI as an 8 bit number for MAVLink
+// RC_CHANNELS_SCALED message
+uint8_t receiver_rssi(void)
+{
+#if RECEIVER_RSSI_PIN != -1
+    float ret = RSSI_pin.read();
+    if (ret >= 255) {
+        return 255;
+    }
+    return (uint8_t)ret;
+#else
+    return 0;
+#endif
+}