Add touch buttons for speaker toggle and music playback.

Enable SoftSPI touch, replace auto beeps with Speaker ON/OFF and Play Music controls, and document usage.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/touch.cpp

@@ -0,0 +1,83 @@
+#include "touch.h"
+#include "pins.h"
+
+#include <Arduino.h>
+
+static void soft_spi_write(uint8_t data) {
+  for (int i = 7; i >= 0; --i) {
+    digitalWrite(TOUCH_MOSI, (data >> i) & 1);
+    digitalWrite(TOUCH_CLK, HIGH);
+    delayMicroseconds(1);
+    digitalWrite(TOUCH_CLK, LOW);
+    delayMicroseconds(1);
+  }
+}
+
+static uint16_t soft_spi_read12() {
+  uint16_t v = 0;
+  for (int i = 0; i < 12; ++i) {
+    digitalWrite(TOUCH_CLK, HIGH);
+    delayMicroseconds(1);
+    v = (v << 1) | (digitalRead(TOUCH_MISO) ? 1 : 0);
+    digitalWrite(TOUCH_CLK, LOW);
+    delayMicroseconds(1);
+  }
+  // 丢掉多余时钟位
+  digitalWrite(TOUCH_CLK, HIGH);
+  delayMicroseconds(1);
+  digitalWrite(TOUCH_CLK, LOW);
+  return v;
+}
+
+static uint16_t xpt_read(uint8_t cmd) {
+  digitalWrite(TOUCH_CS, LOW);
+  soft_spi_write(cmd);
+  delayMicroseconds(5);
+  uint16_t v = soft_spi_read12();
+  digitalWrite(TOUCH_CS, HIGH);
+  return v;
+}
+
+void touch_init() {
+  pinMode(TOUCH_CS, OUTPUT);
+  pinMode(TOUCH_CLK, OUTPUT);
+  pinMode(TOUCH_MOSI, OUTPUT);
+  pinMode(TOUCH_MISO, INPUT);
+  pinMode(TOUCH_IRQ, INPUT);
+  digitalWrite(TOUCH_CS, HIGH);
+  digitalWrite(TOUCH_CLK, LOW);
+  Serial.println("Touch: XPT2046 SoftSPI ready");
+}
+
+void touch_read_cb(lv_indev_t * /*indev*/, lv_indev_data_t *data) {
+  const bool irq = (digitalRead(TOUCH_IRQ) == LOW);
+
+  uint16_t raw_x = xpt_read(0x90);
+  uint16_t raw_y = xpt_read(0xD0);
+
+  if (!irq || raw_x < 80 || raw_y < 80 || raw_x > 4000 || raw_y > 4000) {
+    data->state = LV_INDEV_STATE_RELEASED;
+    return;
+  }
+
+  // LV_DISPLAY_ROTATION_270 → 逻辑 320x240
+  int16_t x = map((int)raw_y, 200, 3800, 0, UI_HOR_RES - 1);
+  int16_t y = map((int)raw_x, 240, 3700, 0, UI_VER_RES - 1);
+
+  if (x < 0) {
+    x = 0;
+  }
+  if (y < 0) {
+    y = 0;
+  }
+  if (x >= UI_HOR_RES) {
+    x = UI_HOR_RES - 1;
+  }
+  if (y >= UI_VER_RES) {
+    y = UI_VER_RES - 1;
+  }
+
+  data->point.x = x;
+  data->point.y = y;
+  data->state = LV_INDEV_STATE_PRESSED;
+}