Display fixes

examples/simple_secure_chat_ui/main.cpp

@@ -900,10 +900,74 @@ void configureDisplay() {
   lcd.fillScreen(0x000000u);
 }
 
+// ── ROOT CAUSE NOTE ──────────────────────────────────────────────────────────
+// Upstream LovyanGFX 1.2.7 does NOT understand the IO_EXPANDER pin encoding
+// (only the mverch67 fork does).  Our SCIndicatorDisplay.h sets
+//   cfg.pin_cs = 4 | IO_EXPANDER  (= 0x44 = 68)
+// During Panel_ST7701_Base::init(), LovyanGFX calls
+//   lgfx::gpio_lo(pin_cs)  // assert CS
+//   ... send SPI init commands (gamma, voltages, RGB666, sleep-out, etc.) ...
+//   lgfx::gpio_hi(pin_cs)  // deassert CS
+// gpio_lo(68) on ESP32-S3 (max GPIO 48) is a silent no-op → CS is NEVER
+// actually asserted → all SPI init commands are sent into the void →
+// the ST7701 never receives its init sequence.
+//
+// This worked SOMETIMES because:
+//   - on soft reboot the ST7701 retained state from the previous boot
+//   - on cold boot from charged caps it was in some semi-init state
+//   - on cold boot from discharged caps it stayed in factory state → stripes
+//
+// FIX: manually assert TCA9535 P0.4 (real LCD CS) LOW before lcd.begin()
+// and deassert it HIGH after. CS stays LOW for the entire LovyanGFX init,
+// so all SPI commands actually reach the ST7701. The internal gpio_lo/hi
+// calls in LovyanGFX become harmless no-ops (they target a non-existent
+// GPIO 68, but our manual TCA9535 CS state is preserved).
+// ────────────────────────────────────────────────────────────────────────────
+
+static void sensecap_lcd_cs_assert() {
+  const uint8_t TCA = 0x20;
+  // Config Port 0: bit 4 (LCD CS) = OUTPUT, bit 5 (LCD RESX) = OUTPUT,
+  // others = INPUT.  0xCF = 1100 1111 (bits 4,5 cleared = output).
+  Wire.beginTransmission(TCA);
+  Wire.write(0x06);   // CONFIG_P0
+  Wire.write(0xCF);
+  uint8_t e1 = Wire.endTransmission();
+
+  // Output Port 0: bit 4 LOW (CS asserted), bit 5 HIGH (RESX deasserted),
+  // all other latches HIGH.  0xEF = 1110 1111.
+  Wire.beginTransmission(TCA);
+  Wire.write(0x02);   // OUTPUT_P0
+  Wire.write(0xEF);
+  uint8_t e2 = Wire.endTransmission();
+
+  Serial.printf("[lcd_cs] assert LOW: cfg_err=%u out_err=%u\n", e1, e2);
+}
+
+static void sensecap_lcd_cs_deassert() {
+  const uint8_t TCA = 0x20;
+  // Output Port 0: all HIGH (CS deasserted, RESX deasserted).
+  Wire.beginTransmission(TCA);
+  Wire.write(0x02);   // OUTPUT_P0
+  Wire.write(0xFF);
+  uint8_t e = Wire.endTransmission();
+  Serial.printf("[lcd_cs] deassert HIGH: out_err=%u\n", e);
+}
+
 void initializeDisplay() {
   ESP_LOGI(TAG, "Initializing display...");
+
+  // Hold the LCD CS LOW manually for the entire lcd.begin() duration so the
+  // ST7701 actually receives the SPI init sequence.  See ROOT CAUSE NOTE above.
+  sensecap_lcd_cs_assert();
+  delay(5);
+
   bool ok = lcd.begin();
   Serial.printf("[display] lcd.begin() = %s  w=%d h=%d\n", ok ? "OK" : "FAIL", lcd.width(), lcd.height());
+
+  // Release LCD CS now that the SPI init sequence is complete.  Subsequent
+  // RGB pixel data goes via the parallel bus and does not need CS.
+  sensecap_lcd_cs_deassert();
+
   lcd.setBrightness(255);
   // Fallback: force GPIO 45 HIGH in case LovyanGFX Light_PWM LEDC setup failed.
   pinMode(45, OUTPUT);

src/helpers/esp32/SenseCapHAL.h

@@ -9,11 +9,15 @@
 // Pin encoding matches LovyanGFX convention: (pin_index | IO_EXPANDER)
 //   IO_EXPANDER = 0x40  (defined as build flag in platformio.ini)
 //
-// SX1262 expander pin assignments (TCA9535 Port 0):
-//   pin 0 = NSS   (EXPANDER_IO_RADIO_NSS)
-//   pin 1 = RESET (EXPANDER_IO_RADIO_RST)
-//   pin 2 = BUSY  (EXPANDER_IO_RADIO_BUSY)
-//   pin 3 = DIO1  (EXPANDER_IO_RADIO_DIO_1)
+// TCA9535 Port 0 pin assignments:
+//   pin 0 = NSS   (EXPANDER_IO_RADIO_NSS)       — SX1262 chip-select
+//   pin 1 = RESET (EXPANDER_IO_RADIO_RST)        — SX1262 hardware reset
+//   pin 2 = BUSY  (EXPANDER_IO_RADIO_BUSY)       — SX1262 busy signal
+//   pin 3 = DIO1  (EXPANDER_IO_RADIO_DIO_1)      — SX1262 IRQ
+//   pin 4 =        display SPI CS                — ST7701 chip-select (must stay OUTPUT HIGH)
+//   pin 5 =        display RESX                  — ST7701 hardware reset (LovyanGFX cfg.pin_rst)
+//   pin 6 =        touch INT                     — FT5x06 interrupt (input, not used in SW)
+//   pin 7 =        touch RST                     — FT5x06 reset (not used in SW)
 //
 // DIO1 interrupt: TCA9535 /INT output → GPIO 42 (IO_EXPANDER_IRQ)
 //   The /INT pin fires FALLING when any input changes.
@@ -85,23 +89,22 @@ public:
   // Both this HAL and the touch-read callback must use the same handle.
   void setMutex(SemaphoreHandle_t m) { _mutex = m; }
 
-  // Call once Wire is running.
-  // Configures TCA9535 Port 0 radio pins (bits 0-3) only.
-  // Bits 4-7 are preserved exactly as LovyanGFX left them
-  // (bit 4 = display SPI CS, must stay OUTPUT HIGH so the
-  //  display ignores any SPI clock pulses from the radio).
+  // Call once Wire is running, AFTER lcd.begin() has completed.
+  // Configures TCA9535 Port 0 radio pins (bits 0-3) and locks bit 4 (display CS).
+  // Bits 5-7 are preserved exactly as LovyanGFX left them.
   void initExpander() {
     // Read the current register values set by LovyanGFX
     uint8_t cur_out = readReg(0x02);
     uint8_t cur_cfg = readReg(0x06);
 
-    // Bits 0-3  (radio pins):     inputs initially, output latch HIGH (de-asserted)
-    //                              RadioLib will reconfigure them as needed.
-    // Bit  4    (display SPI CS):  OUTPUT HIGH — permanently de-asserted.
-    //                              LovyanGFX leaves this pin as INPUT after lcd.begin(),
-    //                              which lets it float. When radio SPI transactions drive
-    //                              GPIO 41/48, a floating CS can corrupt the ST7701 display.
-    // Bits 5-7  (other):           preserved exactly as LovyanGFX left them.
+    // Bits 0-3  (radio):           inputs initially; RadioLib reconfigures as needed.
+    //                              Output latch HIGH = de-asserted.
+    // Bit  4    (display CS):      OUTPUT HIGH — permanently de-asserted.
+    //                              LovyanGFX leaves this as INPUT after lcd.begin();
+    //                              a floating CS allows radio SPI to corrupt the ST7701.
+    // Bit  5    (display RESX):    preserved as OUTPUT HIGH — lcd.begin() already pulsed
+    //                              it LOW→HIGH to reset the ST7701 before init commands.
+    // Bits 6-7  (touch INT/RST):   preserved as LovyanGFX left them (inputs).
     _out0 = (cur_out & 0xE0) | 0x1F;  // bits 0-4 = HIGH,   bits 5-7 = preserved
     _cfg0 = (cur_cfg & 0xE0) | 0x0F;  // bits 0-3 = input,  bit 4 = OUTPUT, bits 5-7 = preserved
 

variants/sensecap_indicator-espnow/SCIndicatorDisplay.h

@@ -58,12 +58,15 @@ public:
         cfg.offset_x = 0;
         cfg.offset_y = 0;
         cfg.offset_rotation = 0;
+        // pin_rst stays at default (no-connect). Upstream LovyanGFX cannot
+        // toggle expander pins. The ST7701 RESX (TCA9535 bit 5) is pulsed
+        // manually by sensecap_lcd_reset_pulse() in main.cpp before lcd.begin().
         _panel_instance.config(cfg);
     }
 
     {
         auto cfg = _panel_instance.config_detail();
-        cfg.pin_cs = 4 | IO_EXPANDER;
+        cfg.pin_cs  = 4 | IO_EXPANDER;  // TCA9535 bit 4 = ST7701 chip-select
         cfg.pin_sclk = 41;
         cfg.pin_mosi = 48;
         cfg.use_psram = 1;