KY-004 按键模块 STM32F103 接线与代码

// 测试修改
/*
 * ============================================================================
 * 13_KY-004 按键 | STM32F103C8T6 BluePill + KY-004 按键模块 + 0.96" OLED(SSD1306)
 * ----------------------------------------------------------------------------
 * 重要概念:
 *   KY-004 网上存在上拉/下拉版本差异, 本块实物已实测确认(2026-08-20):
 *   上拉版, 按下为 LOW(松开 HIGH)。R1(丝印 102)阻值未实测, 不写死。
 *   当前代码 INPUT_PULLUP + HIGH->LOW 下降沿计数, 与实测一致, 保留。
 *     RAW=1 -> RELEASED (未按下) / RAW=0 -> PRESSED (按下)   [已实测确认]
 *
 * 功能:
 *   1. PA0 读取 KY-004 信号端 S, 板载 LED(PC13, 低电平点亮) 跟随按键状态
 *   2. 仅在 HIGH->LOW 下降沿触发计数 COUNT+1 (已实测按下为 LOW; 按下一次计一次, 按住不重复计)
 *   3. 输入经 20ms 稳定确认, 按键抖动/毛刺不计数、不乱跳
 *   4. OLED: 开机页 -> 运行页(STATE: PRESSED/RELEASED 大字反白 + COUNT)
 *   5. 串口 115200, 每 400ms 输出一次状态, 按键变化时立即输出
 *   6. 全部使用 millis() 非阻塞时序, 无长 delay()
 *
 * 接线:
 *   KY-004  -> BluePill:  S->PA0   +->3.3V   -->GND
 *   OLED    -> BluePill:  VCC->3.3V GND->GND  SCL->PB8  SDA->PB9 (I2C 0x3C)
 *
 * 注意: 不同批次 KY-004 引脚丝印可能不同(常见 S/+/- 或 S/VCC/GND), 以模块丝印为准!
 * ============================================================================
 */
#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define FIRMWARE_VERSION "v1.0"

/* ------------------------- 引脚常量 ------------------------- */
constexpr uint8_t BTN_PIN       = PA0;   // KY-004 信号端 S, 数字输入(内部上拉, 已实测按下为 LOW)
constexpr uint8_t LED_PIN       = PC13;  // 板载 LED, 低电平点亮
constexpr uint8_t I2C_SDA_PIN   = PB9;   // OLED SDA
constexpr uint8_t I2C_SCL_PIN   = PB8;   // OLED SCL
constexpr uint8_t OLED_ADDRESS  = 0x3C;  // SSD1306 I2C 地址

/* ------------------------- OLED ------------------------- */
constexpr int SCREEN_WIDTH  = 128;
constexpr int SCREEN_HEIGHT = 64;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

/* ------------------------- 时序参数 (ms) ------------------------- */
constexpr uint32_t BOOT_SCREEN_MS  = 1500UL;   // 开机画面停留时长
constexpr uint32_t DEBOUNCE_MS     = 20UL;     // 按键稳定确认时间(10~30ms)
constexpr uint32_t SERIAL_INTERVAL = 400UL;    // 串口输出周期

/* ------------------------- 状态变量 ------------------------- */
enum class Phase : uint8_t { BOOT, RUN };

Phase    phase        = Phase::BOOT;
uint32_t phaseStartMs = 0;

uint8_t  lastSample   = HIGH;   // 最近一次采样到的电平
uint8_t  confirmedRaw = HIGH;   // 连续稳定 DEBOUNCE_MS 后确认的电平
uint32_t rawChangeMs  = 0;      // 采样电平发生变化的时刻
uint32_t pressCount   = 0;      // 按下次数(仅 HIGH->LOW 下降沿 +1)
bool     stateDirty   = false;  // OLED 需要刷新

bool     displayOk    = false;
uint32_t lastSerialMs = 0;
uint32_t lastLedMs    = 0;

/* ------------------------- OLED 绘制辅助 ------------------------- */

// 屏幕水平居中显示一行文字(默认 5x7 字体)
void drawCentered(const char* s, int16_t y, uint8_t size = 1) {
  display.setTextSize(size);
  int16_t x1, y1;
  uint16_t w, h;
  display.getTextBounds(s, 0, 0, &x1, &y1, &w, &h);
  display.setCursor((SCREEN_WIDTH - (int16_t)w) / 2, y);
  display.print(s);
}

// 开机页
void drawBootPage() {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextWrap(false);
  drawCentered("KY-004 BUTTON", 16);
  drawCentered("Initializing...", 32);
  display.display();
}

// 运行页: pressed=是否按下, 大字反白显示当前状态
void drawRunPage(bool pressed) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextWrap(false);
  drawCentered("KY-004", 0);

  display.setTextSize(1);
  display.setCursor(0, 14);
  display.print("STATE:");

  /* PRESSED / RELEASED 大字反白(按下白底黑字, 松开白字) */
  if (pressed) {
    display.fillRect(0, 26, 128, 18, SSD1306_WHITE);
    display.setTextColor(SSD1306_BLACK);
  } else {
    display.setTextColor(SSD1306_WHITE);
  }
  display.setTextSize(2);
  display.setCursor(0, 27);
  display.print(pressed ? "PRESSED" : "RELEASED");
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  char line[20];
  snprintf(line, sizeof(line), "COUNT: %lu", (unsigned long)pressCount);
  display.setCursor(0, 52);
  display.print(line);

  display.display();
}

/* ------------------------- 进入运行页 ------------------------- */

// 以当前实际电平为基准进入运行, 避免上电时正按着按键被误判为一次"新按下"
void enterRun(uint32_t now) {
  phase        = Phase::RUN;
  phaseStartMs = now;
  lastSample   = digitalRead(BTN_PIN);
  confirmedRaw = lastSample;
  rawChangeMs  = now;
  pressCount   = 0;
  stateDirty   = true;
  lastSerialMs = now;
  digitalWrite(LED_PIN, (confirmedRaw == LOW) ? LOW : HIGH);
  Serial.println("BTN | READY | RUNNING");
}

/* ------------------------- setup / loop ------------------------- */

void setup() {
  Serial.begin(115200);

  pinMode(BTN_PIN, INPUT_PULLUP);   // 已实测按下为 LOW(上拉版), 保留
  pinMode(LED_PIN, OUTPUT);
  digitalWrite(LED_PIN, HIGH);      // 开机 LED 灭(PC13 低电平点亮)

  Wire.setSDA(I2C_SDA_PIN);
  Wire.setSCL(I2C_SCL_PIN);
  Wire.begin();
  Wire.setClock(400000);

  Serial.println("KY-004 BUTTON TEST");
  Serial.print("Firmware: ");
  Serial.println(FIRMWARE_VERSION);
  Serial.println();

  // 先探测 I2C 地址, 给出明确错误信息(display.begin 的返回值不保证真实 ACK)
  Wire.beginTransmission(OLED_ADDRESS);
  if (Wire.endTransmission() != 0) {
    Serial.println("ERROR: OLED not found at 0x3C (check wiring/I2C)");
    displayOk = false;
    return;
  }

  displayOk = display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS, true, false);
  if (!displayOk) {
    Serial.println("ERROR: OLED init failed");
    return;   // loop() 中快速闪灯提示
  }

  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextWrap(false);

  phase        = Phase::BOOT;
  phaseStartMs = millis();
  drawBootPage();
}

void loop() {
  uint32_t now = millis();

  if (!displayOk) {
    // OLED 初始化失败: PC13 快速闪灯报警(非阻塞)
    if (now - lastLedMs >= 100) {
      lastLedMs = now;
      digitalWrite(LED_PIN, !digitalRead(LED_PIN));
    }
    return;
  }

  switch (phase) {

    case Phase::BOOT:
      if (now - phaseStartMs >= BOOT_SCREEN_MS) {
        enterRun(now);
      }
      break;

    case Phase::RUN: {
      /* 1) 采样 + 稳定确认(去抖): 电平连续稳定 DEBOUNCE_MS 才承认变化 */
      uint8_t sample = digitalRead(BTN_PIN);
      if (sample != lastSample) {
        lastSample  = sample;
        rawChangeMs = now;               // 出现变化, 重新计时
      }
      if (now - rawChangeMs >= DEBOUNCE_MS) {
        if (confirmedRaw != lastSample) {  // 稳定变化被确认
          uint8_t prev = confirmedRaw;
          confirmedRaw = lastSample;
          if (prev == HIGH && confirmedRaw == LOW) {
            pressCount++;                  // 仅 HIGH->LOW 下降沿计数一次
          }
          stateDirty = true;
        }
      }

      /* 2) LED: 按下->亮, 松开->灭 (PC13 低电平点亮) */
      digitalWrite(LED_PIN, (confirmedRaw == LOW) ? LOW : HIGH);

      /* 3) 串口: 每 400ms 输出一次; 状态变化时立即输出, 与 OLED 一致 */
      bool stateChanged = stateDirty;
      if (stateChanged || now - lastSerialMs >= SERIAL_INTERVAL) {
        lastSerialMs = now;
        Serial.print("BTN | RAW=");
        Serial.print(confirmedRaw);
        Serial.print(" | STATE=");
        Serial.print(confirmedRaw == LOW ? "PRESSED  " : "RELEASED ");
        Serial.print("| COUNT=");
        Serial.println(pressCount);
      }

      /* 4) OLED: 状态变化立即刷新, 不变不刷 */
      if (stateDirty) {
        stateDirty = false;
        drawRunPage(confirmedRaw == LOW);
      }
      break;
    }
  }
}