From 0feedbec2e40715c224733a9cf64c70285ae696b Mon Sep 17 00:00:00 2001
From: agessaman <adam@gessaman.com>
Date: Sun, 23 Aug 2026 15:43:22 -0700
Subject: [PATCH] fix(boards): reset Heltec V4 R8 TFT on GPIO 21

GPIO 21 is the Expansion Kit V2 panel reset, not touch reset.
Leaving RST unwired left the ST7789 blank after a bogus touch pulse.
---
 src/helpers/ui/ST7789LCDDisplay.cpp       | 24 +++++++++++++++--------
 variants/heltec_v4_r8/HeltecV4R8Board.cpp |  2 ++
 variants/heltec_v4_r8/platformio.ini      |  3 +--
 3 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/src/helpers/ui/ST7789LCDDisplay.cpp b/src/helpers/ui/ST7789LCDDisplay.cpp
index a9f30dd5..6e0862c3 100644
--- a/src/helpers/ui/ST7789LCDDisplay.cpp
+++ b/src/helpers/ui/ST7789LCDDisplay.cpp
@@ -4,6 +4,10 @@
   #define PIN_TFT_MISO -1
 #endif
 
+#ifndef PIN_TFT_LEDA_CTL_ACTIVE
+  #define PIN_TFT_LEDA_CTL_ACTIVE HIGH
+#endif
+
 #ifndef DISPLAY_ROTATION
   #define DISPLAY_ROTATION 3
 #endif
@@ -36,11 +40,14 @@ ColorVal UIColor::corp_blue = 0x001A;
 
 bool ST7789LCDDisplay::begin() {
   if (!_isOn) {
-    if (_peripher_power) _peripher_power->claim();
+    if (_peripher_power) {
+      _peripher_power->claim();
+      delay(100);
+    }
 
     if (PIN_TFT_LEDA_CTL != -1) {
       pinMode(PIN_TFT_LEDA_CTL, OUTPUT);
-      digitalWrite(PIN_TFT_LEDA_CTL, HIGH);
+      digitalWrite(PIN_TFT_LEDA_CTL, !PIN_TFT_LEDA_CTL_ACTIVE);
     }
 
     // Im not sure if this is just a t-deck problem or not, if your display is slow try this.
@@ -55,9 +62,13 @@ bool ST7789LCDDisplay::begin() {
 
     display.fillScreen(ST77XX_BLACK);
     display.setTextColor(ST77XX_WHITE);
-    display.setTextSize(2 * DISPLAY_SCALE_X); 
+    display.setTextSize(2 * DISPLAY_SCALE_X);
     display.cp437(true); // Use full 256 char 'Code Page 437' font
-  
+
+    if (PIN_TFT_LEDA_CTL != -1) {
+      digitalWrite(PIN_TFT_LEDA_CTL, PIN_TFT_LEDA_CTL_ACTIVE);
+    }
+
     _isOn = true;
   }
 
@@ -71,14 +82,11 @@ void ST7789LCDDisplay::turnOn() {
 void ST7789LCDDisplay::turnOff() {
   if (_isOn) {
     if (PIN_TFT_LEDA_CTL != -1) {
-      digitalWrite(PIN_TFT_LEDA_CTL, HIGH);
+      digitalWrite(PIN_TFT_LEDA_CTL, !PIN_TFT_LEDA_CTL_ACTIVE);
     }
     if (PIN_TFT_RST != -1) {
       digitalWrite(PIN_TFT_RST, LOW);
     }
-    if (PIN_TFT_LEDA_CTL != -1) {
-      digitalWrite(PIN_TFT_LEDA_CTL, LOW);
-    }
     _isOn = false;
 
     if (_peripher_power) _peripher_power->release();
diff --git a/variants/heltec_v4_r8/HeltecV4R8Board.cpp b/variants/heltec_v4_r8/HeltecV4R8Board.cpp
index 11aa9f64..580662b3 100644
--- a/variants/heltec_v4_r8/HeltecV4R8Board.cpp
+++ b/variants/heltec_v4_r8/HeltecV4R8Board.cpp
@@ -8,6 +8,8 @@ void HeltecV4R8Board::begin() {
 
   loRaFEMControl.init();
 
+  // Expansion Kit CHSC6X touch RST/INT are unwired. GPIO 21 is TFT RST
+  // (PIN_TFT_RST), owned by ST7789LCDDisplay. Do not pulse it here.
 #ifdef PIN_TOUCH_RST
   pinMode(PIN_TOUCH_RST, OUTPUT);
   digitalWrite(PIN_TOUCH_RST, HIGH);
diff --git a/variants/heltec_v4_r8/platformio.ini b/variants/heltec_v4_r8/platformio.ini
index 95fa3a2e..ea788e10 100644
--- a/variants/heltec_v4_r8/platformio.ini
+++ b/variants/heltec_v4_r8/platformio.ini
@@ -65,7 +65,7 @@ build_flags =
   -D PIN_BOARD_SCL=18
   -D DISPLAY_SCALE_X=2.5
   -D DISPLAY_SCALE_Y=3.75
-  -D PIN_TFT_RST=-1
+  -D PIN_TFT_RST=21
   -D PIN_TFT_VDD_CTL=-1
   -D PIN_TFT_LEDA_CTL=44
   -D PIN_TFT_LEDA_CTL_ACTIVE=HIGH
@@ -75,7 +75,6 @@ build_flags =
   -D PIN_TFT_SDA=15
   -D PIN_TFT_MISO=45
   -D PIN_BUZZER=4
-  -D PIN_TOUCH_RST=21
 build_src_filter = ${Heltec_v4_r8.build_src_filter}
   +<helpers/ui/buzzer.cpp>
 lib_deps =