From 01b0e0c27cf91169fb00c5e18197e613539a5339 Mon Sep 17 00:00:00 2001
From: Lanea Lucy S <lanealucy@gmail.com>
Date: Wed, 20 Mar 2024 13:21:49 +0100
Subject: [PATCH] AP_Relay: added relay output invert function

---
 libraries/AP_Relay/AP_Relay.cpp        | 8 ++++++++
 libraries/AP_Relay/AP_Relay_Params.cpp | 9 ++++++++-
 libraries/AP_Relay/AP_Relay_Params.h   | 1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/libraries/AP_Relay/AP_Relay.cpp b/libraries/AP_Relay/AP_Relay.cpp
index 4aa31ec215737..fe3a73ab2d984 100644
--- a/libraries/AP_Relay/AP_Relay.cpp
+++ b/libraries/AP_Relay/AP_Relay.cpp
@@ -408,6 +408,10 @@ void AP_Relay::set_pin_by_instance(uint8_t instance, bool value)
 
     const bool initial_value = get_pin(pin);
 
+    if (_params[instance].inverted > 0) {
+        value = !value;
+    }
+
     if (initial_value != value) {
         set_pin(pin, value);
 #if HAL_LOGGING_ENABLED
@@ -496,6 +500,10 @@ bool AP_Relay::get(uint8_t instance) const
         return false;
     }
 
+    if (_params[instance].inverted > 0) {
+        return !get_pin(_params[instance].pin.get());
+    }
+
     return get_pin(_params[instance].pin.get());
 }
 
diff --git a/libraries/AP_Relay/AP_Relay_Params.cpp b/libraries/AP_Relay/AP_Relay_Params.cpp
index 99abbcb77e6bb..5ca1e1d1dac73 100644
--- a/libraries/AP_Relay/AP_Relay_Params.cpp
+++ b/libraries/AP_Relay/AP_Relay_Params.cpp
@@ -60,11 +60,18 @@ const AP_Param::GroupInfo AP_Relay_Params::var_info[] = {
 
     // @Param: DEFAULT
     // @DisplayName: Relay default state
-    // @Description: Should the relay default to on or off, this only applies to RELAYx_FUNC "Relay" (1). All other uses will pick the appropriate default output state from within the controlling function's parameters.
+    // @Description: Should the relay default to on or off, this only applies to RELAYx_FUNC "Relay" (1). All other uses will pick the appropriate default output state from within the controlling function's parameters. Note that if INVERTED is set then the default is inverted.
     // @Values: 0: Off,1:On,2:NoChange
     // @User: Standard
     AP_GROUPINFO("DEFAULT", 3, AP_Relay_Params, default_state, (float)DefaultState::OFF),
 
+    // @Param: INVERTED
+    // @DisplayName: Relay invert output signal
+    // @Description: Should the relay output signal be inverted. If enabled, relay on would be pin low and relay off would be pin high. NOTE: this impact's DEFAULT.
+    // @Values: 0:Normal,1:Inverted
+    // @User: Standard
+    AP_GROUPINFO("INVERTED", 4, AP_Relay_Params, inverted, false),
+
     AP_GROUPEND
 
 };
diff --git a/libraries/AP_Relay/AP_Relay_Params.h b/libraries/AP_Relay/AP_Relay_Params.h
index 9b6a9d1cc5d8d..694b7202ac664 100644
--- a/libraries/AP_Relay/AP_Relay_Params.h
+++ b/libraries/AP_Relay/AP_Relay_Params.h
@@ -70,4 +70,5 @@ class AP_Relay_Params {
     AP_Enum<FUNCTION> function;            // relay function
     AP_Int16 pin;                          // gpio pin number
     AP_Enum<DefaultState> default_state;  // default state
+    AP_Int8 inverted;                       // inverted signal
 };