From 5570b6bbc6542642735f774b95af56451ca87dda Mon Sep 17 00:00:00 2001
From: Kevin Hester <kevinh@geeksville.com>
Date: Thu, 22 Aug 2024 10:15:23 -0700
Subject: [PATCH] change GPS to use virtual GPIOs (for #4154)

---
 src/GpioLogic.cpp |  6 ++++++
 src/GpioLogic.h   |  2 +-
 src/gps/GPS.cpp   | 27 +++++++++++++++++----------
 src/gps/GPS.h     | 11 +++++++++--
 4 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/src/GpioLogic.cpp b/src/GpioLogic.cpp
index d164615a7..c23c40a7f 100644
--- a/src/GpioLogic.cpp
+++ b/src/GpioLogic.cpp
@@ -10,6 +10,12 @@ void GpioVirtPin::set(bool value)
     }
 }
 
+void GpioHwPin::set(bool value)
+{
+    pinMode(num, OUTPUT);
+    digitalWrite(num, value);
+}
+
 GpioTransformer::GpioTransformer(GpioPin *outPin) : outPin(outPin) {}
 
 void GpioTransformer::set(bool value)
diff --git a/src/GpioLogic.h b/src/GpioLogic.h
index 27e85d55b..c5a3cefa9 100644
--- a/src/GpioLogic.h
+++ b/src/GpioLogic.h
@@ -29,7 +29,7 @@ class GpioHwPin : public GpioPin
   public:
     explicit GpioHwPin(uint32_t num) : num(num) {}
 
-    void set(bool value) { digitalWrite(num, value); }
+    void set(bool value);
 };
 
 class GpioTransformer;
diff --git a/src/gps/GPS.cpp b/src/gps/GPS.cpp
index 7d7de8700..f7db1367a 100644
--- a/src/gps/GPS.cpp
+++ b/src/gps/GPS.cpp
@@ -2,6 +2,7 @@
 #if !MESHTASTIC_EXCLUDE_GPS
 #include "Default.h"
 #include "GPS.h"
+#include "GpioLogic.h"
 #include "NodeDB.h"
 #include "PowerMon.h"
 #include "RTC.h"
@@ -875,16 +876,8 @@ void GPS::writePinEN(bool on)
     if (HW_VENDOR == meshtastic_HardwareModel_RAK4631 && (rotaryEncoderInterruptImpl1 || upDownInterruptImpl1))
         return;
 
-    // Abort: if pin unset
-    if (!en_gpio)
-        return;
-
-    // Determine new value for the pin
-    bool val = GPS_EN_ACTIVE ? on : !on;
-
     // Write and log
-    pinMode(en_gpio, OUTPUT);
-    digitalWrite(en_gpio, val);
+    enablePin->set(on);
 #ifdef GPS_EXTRAVERBOSE
     LOG_DEBUG("Pin EN %s\n", val == HIGH ? "HIGH" : "LOW");
 #endif
@@ -1421,7 +1414,21 @@ GPS *GPS::createGps()
     GPS *new_gps = new GPS;
     new_gps->rx_gpio = _rx_gpio;
     new_gps->tx_gpio = _tx_gpio;
-    new_gps->en_gpio = _en_gpio;
+
+    if (_en_gpio) {
+        GpioPin *p = new GpioHwPin(_en_gpio);
+
+        if (!GPS_EN_ACTIVE) { // Need to invert the pin before hardware
+            auto virtPin = new GpioVirtPin();
+            new GpioNotTransformer(
+                virtPin, p); // We just leave this created object on the heap so it can stay watching virtPin and driving en_gpio
+            p = virtPin;
+        }
+        new_gps->enablePin = p;
+    } else {
+        // Just use a simulated pin
+        new_gps->enablePin = new GpioVirtPin();
+    }
 
 #ifdef PIN_GPS_PPS
     // pulse per second
diff --git a/src/gps/GPS.h b/src/gps/GPS.h
index 96171cba5..494bddae8 100644
--- a/src/gps/GPS.h
+++ b/src/gps/GPS.h
@@ -3,6 +3,7 @@
 #if !MESHTASTIC_EXCLUDE_GPS
 
 #include "GPSStatus.h"
+#include "GpioLogic.h"
 #include "Observer.h"
 #include "TinyGPS++.h"
 #include "concurrency/OSThread.h"
@@ -73,7 +74,6 @@ class GPS : private concurrency::OSThread
     uint32_t lastWakeStartMsec = 0, lastSleepStartMsec = 0, lastFixStartMsec = 0;
     uint32_t rx_gpio = 0;
     uint32_t tx_gpio = 0;
-    uint32_t en_gpio = 0;
 
     int speedSelect = 0;
     int probeTries = 2;
@@ -152,6 +152,13 @@ class GPS : private concurrency::OSThread
 
     meshtastic_Position p = meshtastic_Position_init_default;
 
+    /** This is normally bound to config.position.gps_en_gpio but some rare boards (like heltec tracker) need more advanced
+     * implementations. Those boards will set this public variable to a custom implementation.
+     *
+     * Normally set by GPS::createGPS()
+     */
+    GpioPin *enablePin;
+
     GPS() : concurrency::OSThread("GPS") {}
 
     virtual ~GPS();
@@ -303,4 +310,4 @@ class GPS : private concurrency::OSThread
 };
 
 extern GPS *gps;
-#endif // Exclude GPS
+#endif // Exclude GPS
\ No newline at end of file