From 59238085265e594191d0df05f6b2a3288895c5e9 Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Wed, 2 Jan 2013 12:51:56 +1100
Subject: [PATCH] AP_Relay: allow for no relay pin

---
 libraries/AP_Relay/AP_Relay.cpp | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_Relay/AP_Relay.cpp b/libraries/AP_Relay/AP_Relay.cpp
index 07b8802c0c..85bf7a1bb6 100644
--- a/libraries/AP_Relay/AP_Relay.cpp
+++ b/libraries/AP_Relay/AP_Relay.cpp
@@ -17,35 +17,50 @@ extern const AP_HAL::HAL& hal;
 #elif CONFIG_HAL_BOARD == HAL_BOARD_APM2 || CONFIG_HAL_BOARD == HAL_BOARD_AVR_SITL
 #define RELAY_PIN 26
 #else
-#error "no RELAY_PIN defined for this board"
+// no relay for this board
+#define RELAY_PIN -1
 #endif
 
 void AP_Relay::init() {
+#if RELAY_PIN != -1
     hal.gpio->pinMode(RELAY_PIN, GPIO_OUTPUT);
+#endif
 }
 
 void AP_Relay::on() {
+#if RELAY_PIN != -1
     hal.gpio->write(RELAY_PIN, 1);
+#endif
 }
 
 
 void AP_Relay::off() {
+#if RELAY_PIN != -1
     hal.gpio->write(RELAY_PIN, 0);
+#endif
 }
 
 
 void AP_Relay::toggle() {
+#if RELAY_PIN != -1
     bool ison = hal.gpio->read(RELAY_PIN);
     if (ison)
         off();
     else
         on();
+#endif
 }
 
 void AP_Relay::set(bool status){
+#if RELAY_PIN != -1
     hal.gpio->write(RELAY_PIN, status);
+#endif
 }
 
 bool AP_Relay::get() {
+#if RELAY_PIN != -1
     return hal.gpio->read(RELAY_PIN); 
+#else
+    return false;
+#endif
 }