Ultrasonic LCD Meter — Arduino Uno simulation

Ultrasonic Distance Meter with LCD2004 display on Arduino Uno

An interactive Arduino Uno circuit simulation you can run free in your browser on Velxio, by leikz.

Components

• Grove Ultrasonic Ranger
• Junction
• Lcd2004 I2C

Sketch code

/*
 * 完全无库版：Grove 超声波 + LCD2004(I2C)
 * 直接操作 TWI 寄存器，不 include 任何库
 */

#define SIG_PIN   2
#define LCD_ADDR  0x27

/* ---------- 裸 I2C / TWI ---------- */
void i2cInit() {
    TWBR = 72;        // 100kHz @ 16MHz
    TWSR = 0x00;      // 预分频 = 1
}
void i2cStart() {
    TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
    while (!(TWCR & (1<<TWINT)));
}
void i2cStop() {
    TWCR = (1<<TWINT) | (1<<TWSTO) | (1<<TWEN);
}
void i2cWrite(byte d) {
    TWDR = d;
    TWCR = (1<<TWINT) | (1<<TWEN);
    while (!(TWCR & (1<<TWINT)));
}
void i2cSend(byte d) {
    i2cStart();
    i2cWrite(LCD_ADDR << 1);
    i2cWrite(d);
    i2cStop();
}

/* ---------- LCD 2004 ---------- */
void lcdByte(byte val, bool isData) {
    byte rs = isData ? 0x01 : 0x00;
    i2cSend((val & 0xF0) | rs | 0x08 | 0x04);
    i2cSend((val & 0xF0) | rs | 0x08);
    i2cSend(((val<<4) & 0xF0) | rs | 0x08 | 0x04);
    i2cSend(((val<<4) & 0xF0) | rs | 0x08);
    delayMicroseconds(50);
}
void lcdCmd(byte c)  { lcdByte(c, false); }
void lcdData(byte d) { lcdByte(d, true);  }

void lcdInit() {
    delay(50);
    lcdCmd(0x30); delay(5);
    lcdCmd(0x30); delayMicroseconds(150);
    lcdCmd(0x30); delayMicroseconds(150);
    lcdCmd(0x20); delayMicroseconds(150);
    lcdCmd(0x28);
    lcdCmd(0x0C);
    lcdCmd(0x06);
    lcdCmd(0x01);
    delay(2);
}

void lcdPos(byte col, byte row) {
    static byte off[] = {0x00, 0x40, 0x14, 0x54};
    lcdCmd(0x80 | (col + off[row]));
}

void lcdStr(const char* s) { while (*s) lcdData(*s++); }

/* ---------- 超声波 ---------- */
long readCm() {
    long sum = 0;
    long minUs = 99999, maxUs = 0;
    for (byte i = 0; i < 5; i++) {
        pinMode(SIG_PIN, OUTPUT);
        digitalWrite(SIG_PIN, LOW);
        delayMicroseconds(2);
        digitalWrite(SIG_PIN, HIGH);
        delayMicroseconds(10);
        digitalWrite(SIG_PIN, LOW);
        pinMode(SIG_PIN, INPUT);
        long us = pulseIn(SIG_PIN, HIGH, 50000UL);
        if (us == 0) return -1;
        sum += us;
        if (us < minUs) minUs = us;
        if (us > maxUs) maxUs = us;
        delay(15);
    }
    long avg = (sum - minUs - maxUs) / 3;
    long cm = (long)(avg / 58.0 + 2.0);
    if (cm < 3) cm = 2;        // 传感器最小量程 2cm，再近就钳位
    return cm;
}

void setup() {
    i2cInit();
    lcdInit();
    lcdPos(0, 0);
    lcdStr("Ultrasonic Meter");
}

void loop() {
    long cm = readCm();
    lcdPos(0, 1);
    if (cm < 0) lcdStr("Out of range    ");
    else {
        char buf[16];
        snprintf(buf, sizeof(buf), "%ld cm            ", cm);
        lcdStr(buf);
    }
    delay(200);
}

More projects by leikz

• 作业2 — Arduino Mega
• 超声波测距仪 LCD2004 — Arduino Uno