fix: backlight on CrowPanel Advance 4.3/5.0/7.0 V1.2+ hardware (STC8H1K28 MCU)

include/graphics/LGFX/LGFX_ELECROW70.h

@@ -10,6 +10,22 @@
 #define FREQ_WRITE 14000000
 #endif
 
+// Backlight / buzzer / speaker / touch control on CrowPanel Advance 4.3"/5.0"/7.0":
+//   - HW rev V1.0/V1.1: TCA9534 I/O expander at I2C 0x18 (pin 1 gates backlight).
+//   - HW rev V1.2+ (incl. V1.3/V1.4): STC8H1K28 microcontroller at I2C 0x30.
+//     Writing a single byte selects the function, per Elecrow's reference code:
+//       V1.2:  0x05..0x10  (0x05 = off, 0x10 = max)
+//       V1.3+: 0..245      (0 = max, 244 = min, 245 = off)
+//       Both:  246/247 buzzer on/off, 248/249 speaker on/off, 250 activate touch
+//   Sending a value in the V1.3+ scale to a V1.2 board is a no-op (undefined
+//   commands are ignored), so we send the V1.3+ "max brightness" byte and let
+//   V1.2 hardware stay dark rather than risk flipping buzzer/speaker pins by
+//   reusing bytes with overlapping meanings.
+#define CROW_MCU_I2C_ADDR 0x30
+#define CROW_MCU_BL_MAX 0
+#define CROW_MCU_BL_OFF 245
+#define CROW_MCU_TOUCH_ACTIVATE 250
+
 class LGFX_ELECROW70 : public lgfx::LGFX_Device
 {
     lgfx::Bus_RGB _bus_instance;
@@ -24,24 +40,54 @@ class LGFX_ELECROW70 : public lgfx::LGFX_Device
 
     bool init_impl(bool use_reset, bool use_clear) override
     {
-        ioex.attach(Wire);
-        ioex.setDeviceAddress(0x18);
-        ioex.config(1, TCA9534::Config::OUT);
-        ioex.config(2, TCA9534::Config::OUT);
-        ioex.config(3, TCA9534::Config::OUT);
-        ioex.config(4, TCA9534::Config::OUT);
-
-        ioex.output(1, TCA9534::Level::H);
-        ioex.output(3, TCA9534::Level::L);
-        ioex.output(4, TCA9534::Level::H);
-
-        pinMode(1, OUTPUT);
-        digitalWrite(1, LOW);
-        ioex.output(2, TCA9534::Level::L);
-        delay(20);
-        ioex.output(2, TCA9534::Level::H);
-        delay(100);
-        pinMode(1, INPUT);
+        // Distinguish hardware revisions by probing for the TCA9534 I/O
+        // expander at 0x18: present on V1.0/V1.1, absent on V1.2+ where
+        // its role has been taken over by the STC8H1K28 microcontroller
+        // at 0x30. Probing 0x18 is reliable even on cold boot — the
+        // TCA9534 is passive and responds immediately, unlike the MCU
+        // which needs a wake sequence before it ACKs.
+        Wire.beginTransmission(0x18);
+        bool hasExpander = (Wire.endTransmission() == 0);
+        hasMcu = !hasExpander;
+
+        if (hasMcu) {
+            // V1.2+ wake sequence, mirrors Elecrow's CrowPanel-Advance-7
+            // reference code. The first write may NACK because the MCU
+            // is still booting; the GPIO1 pulse then latches/wakes it,
+            // and subsequent writes set the desired state. Repeat the
+            // command a few times so we don't rely on any single
+            // transmission succeeding.
+            for (int attempt = 0; attempt < 5; ++attempt) {
+                writeMcu(CROW_MCU_TOUCH_ACTIVATE);
+                pinMode(1, OUTPUT);
+                digitalWrite(1, LOW);
+                delay(120);
+                pinMode(1, INPUT);
+                delay(100);
+                writeMcu(CROW_MCU_BL_MAX);
+                delay(20);
+            }
+        } else {
+            // V1.0/V1.1: TCA9534 I/O expander at 0x18.
+            ioex.attach(Wire);
+            ioex.setDeviceAddress(0x18);
+            ioex.config(1, TCA9534::Config::OUT);
+            ioex.config(2, TCA9534::Config::OUT);
+            ioex.config(3, TCA9534::Config::OUT);
+            ioex.config(4, TCA9534::Config::OUT);
+
+            ioex.output(1, TCA9534::Level::H);
+            ioex.output(3, TCA9534::Level::L);
+            ioex.output(4, TCA9534::Level::H);
+
+            pinMode(1, OUTPUT);
+            digitalWrite(1, LOW);
+            ioex.output(2, TCA9534::Level::L);
+            delay(20);
+            ioex.output(2, TCA9534::Level::H);
+            delay(100);
+            pinMode(1, INPUT);
+        }
 
         return LGFX_Device::init_impl(use_reset, use_clear);
     }
@@ -137,15 +183,31 @@ class LGFX_ELECROW70 : public lgfx::LGFX_Device
 
     void sleep(void)
     {
-        ioex.output(1, TCA9534::Level::L);
+        if (hasMcu) {
+            writeMcu(CROW_MCU_BL_OFF);
+        } else {
+            ioex.output(1, TCA9534::Level::L);
+        }
         _panel->setSleep(true);
     }
     void wakeup(void)
     {
-        ioex.output(1, TCA9534::Level::H);
+        if (hasMcu) {
+            writeMcu(CROW_MCU_BL_MAX);
+        } else {
+            ioex.output(1, TCA9534::Level::H);
+        }
         _panel->setSleep(false);
     }
 
   private:
+    void writeMcu(uint8_t cmd)
+    {
+        Wire.beginTransmission(CROW_MCU_I2C_ADDR);
+        Wire.write(cmd);
+        Wire.endTransmission();
+    }
+
     TCA9534 ioex;
+    bool hasMcu = false;
 };