S3 hub Phase 1: round LCD + touch bring-up (LovyanGFX)

ESP32-S3-Touch-LCD-1.28 first light: GC9A01 round display + backlight + CST816S
touch working via LovyanGFX. Draws a label and red dots on touch.

- src/hub_s3.cpp: LovyanGFX LGFX config for this board (GC9A01 SPI
  SCLK10/MOSI11/MISO12/CS9/DC8/RST14, backlight GPIO2; CST816S touch I2C
  SDA6/SCL7 polled, addr 0x15).
- platformio.ini: new [env:hub_s3] (esp32-s3-devkitc-1, 4MB, LovyanGFX).
  Not in default_envs. Flash: esp32s3, bootloader@0x0 +boot_app0@0xe000.

Foundation for the on-device UI hub. PSRAM not yet enabled (not needed for
bring-up; will enable for LVGL). Next: I2C control bus to Boards B/C.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

platformio.ini

@@ -37,3 +37,16 @@ build_flags = '-DTARGET_SPEAKER="JBL Charge 5"'
 [env:source_cardo]
 build_src_filter = +<board_source.cpp>
 build_flags = '-DTARGET_SPEAKER="Tangerine EDGE"'
+
+; --- Hub: ESP32-S3-Touch-LCD-1.28 (round GC9A01 LCD + CST816S touch) ----------
+;     Different chip (esp32s3) from the relay boards. Drives the UI; later the
+;     wired control bus to Boards B/C. NOT in default_envs — build with -e hub_s3.
+[env:hub_s3]
+platform = espressif32 @ ~6.6.0
+board = esp32-s3-devkitc-1
+framework = arduino
+board_upload.flash_size = 4MB
+board_build.partitions = default.csv
+monitor_speed = 115200
+build_src_filter = +<hub_s3.cpp>
+lib_deps = lovyan03/LovyanGFX@^1.1.16

src/hub_s3.cpp

@@ -0,0 +1,102 @@
+/**
+ * BikeAudio — Hub (ESP32-S3-Touch-LCD-1.28) : PHASE 1 bring-up
+ *
+ * First light: drive the round GC9A01 LCD + backlight, and read the CST816S
+ * touch, to prove the board before building the GUI. No control bus / GUI yet.
+ *
+ * Board pins (Waveshare ESP32-S3-Touch-LCD-1.28):
+ *   GC9A01 SPI: SCLK=10 MOSI=11 MISO=12 CS=9 DC=8 RST=14   backlight=2
+ *   CST816S touch (I2C): SDA=6 SCL=7  (polled; INT left unused)
+ *
+ * Build: pio run -e hub_s3   |   flash: esp32s3, bootloader@0x0
+ */
+
+#define LGFX_USE_V1
+#include <Arduino.h>
+#include <LovyanGFX.hpp>
+
+class LGFX : public lgfx::LGFX_Device {
+    lgfx::Panel_GC9A01    _panel;
+    lgfx::Bus_SPI         _bus;
+    lgfx::Light_PWM       _light;
+    lgfx::Touch_CST816S   _touch;
+public:
+    LGFX() {
+        { auto c = _bus.config();
+          c.spi_host   = SPI2_HOST;
+          c.spi_mode   = 0;
+          c.freq_write = 40000000;
+          c.pin_sclk   = 10;
+          c.pin_mosi   = 11;
+          c.pin_miso   = 12;
+          c.pin_dc     = 8;
+          _bus.config(c); _panel.setBus(&_bus); }
+
+        { auto c = _panel.config();
+          c.pin_cs        = 9;
+          c.pin_rst       = 14;
+          c.panel_width   = 240;
+          c.panel_height  = 240;
+          c.offset_x      = 0;
+          c.offset_y      = 0;
+          c.readable      = false;
+          c.invert        = true;     // GC9A01 typically needs inversion
+          c.rgb_order     = false;
+          _panel.config(c); }
+
+        { auto c = _light.config();
+          c.pin_bl      = 2;
+          c.freq        = 12000;
+          c.pwm_channel = 7;
+          _light.config(c); _panel.setLight(&_light); }
+
+        { auto c = _touch.config();
+          c.i2c_port = 0;
+          c.pin_sda  = 6;
+          c.pin_scl  = 7;
+          c.pin_int  = -1;            // poll over I2C (avoid INT-pin ambiguity)
+          c.pin_rst  = -1;
+          c.i2c_addr = 0x15;
+          c.freq     = 400000;
+          c.x_min = 0; c.x_max = 239; c.y_min = 0; c.y_max = 239;
+          _touch.config(c); _panel.setTouch(&_touch); }
+
+        setPanel(&_panel);
+    }
+};
+
+LGFX lcd;
+
+void setup() {
+    Serial.begin(115200);
+    delay(300);
+    Serial.println("=== BikeAudio Hub — S3 round LCD first light ===");
+
+    lcd.init();
+    lcd.setRotation(0);
+    lcd.setBrightness(200);
+    lcd.fillScreen(TFT_BLACK);
+    lcd.drawCircle(120, 120, 118, TFT_DARKGREY);
+    lcd.setTextColor(TFT_CYAN, TFT_BLACK);
+    lcd.setTextDatum(middle_center);
+    lcd.drawString("BikeAudio", 120, 100, &fonts::FreeSansBold18pt7b);
+    lcd.setTextColor(TFT_WHITE, TFT_BLACK);
+    lcd.drawString("hub: first light", 120, 140, &fonts::Font2);
+    lcd.drawString("touch me", 120, 160, &fonts::Font2);
+    Serial.println("[LCD] drawn; touch to draw dots");
+}
+
+void loop() {
+    int32_t x, y;
+    if (lcd.getTouch(&x, &y)) {
+        lcd.fillCircle(x, y, 5, TFT_RED);
+        Serial.printf("[TOUCH] %d, %d\n", x, y);
+    }
+
+    static unsigned long last = 0;
+    if (millis() - last > 5000) {
+        Serial.printf("[hub] alive heap=%u psram=%u\n", ESP.getFreeHeap(), ESP.getFreePsram());
+        last = millis();
+    }
+    delay(15);
+}