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本項目是一個采用Traffic LED模塊、Arduino Uno/Nano，以及TOF10120飛行時間傳感器的工業(yè)級智能停車系統(tǒng)。項目采用一塊切邊的墊子作為停車區(qū)，先測量墊子長度，再根據(jù)這個數(shù)值定義不同距離的代碼，一個接一個的點(diǎn)亮（ON）和熄滅（OFF）這些LEDs，以幫助司機(jī)安全停車：
當(dāng)汽車即將進(jìn)入停車區(qū)域時，綠色LED點(diǎn)亮。然后，黃色LED點(diǎn)亮，提醒司機(jī)即將接近目標(biāo)停車位置，這表明汽車車身已經(jīng)有一半位于停車區(qū)域。
當(dāng)紅色LED開始閃爍時，警告司機(jī)緩慢行駛并留意，到達(dá)停車點(diǎn)后關(guān)閉汽車，或者繼續(xù)移動直到紅色LED停止閃爍。
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作為一個用以理解停車系統(tǒng)的原型，項目使用的均為廉價元件。讀者可對電路進(jìn)行升級，如改變代碼中的測量距離數(shù)值，甚至替換電路中的傳感器等，使項目更加實用。
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ToF10120飛行時間傳感器
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tof10120激光模塊最大的優(yōu)勢在于測距遠(yuǎn)、操作簡單，程序中僅僅需要通過單片機(jī)給模塊串口發(fā)送命令字符串，就可以向單片機(jī)發(fā)送回距離數(shù)據(jù)。如果發(fā)送自動測距的字符串命令，則模塊會按照一定頻率自動回送數(shù)據(jù)，相關(guān)物理量都可以通過命令字符串設(shè)置。傳感器僅需要串口就可以實現(xiàn)。
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TOF10120基于Sharp低成本標(biāo)準(zhǔn)CMOS工藝和SPAD技術(shù)，可為自動對焦（AF）提供精確、可重復(fù)的長距離測量，測量結(jié)果不受物體反射的影響。主要特點(diǎn)包括：
?采用940nm激光；
?小型陶瓷封裝（20×13.2×2.0mm）；
? 可在室內(nèi)測量長達(dá)1.8m長度，精度5％；
?測量距離不受姆堡反射的影響；
?先進(jìn)廣促俄串?dāng)_補(bǔ)償技術(shù)；
?30ms高速測量；
?單電源供電；
?Txd接口用于設(shè)備控制和數(shù)據(jù)傳送；
?無鉛，符合RoHS指令。
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TOF10120典型測距范圍為100-1800mm，電源電壓3-5v，消耗電流35mA，兼容Arduino、ESP8266、ESP32等5V和3.3V控制板，適合-20°C to +70°C等室內(nèi)外環(huán)境。
TOF10120支持UART、I2C通訊，1#引腳、2#引腳、3#引腳、4#引腳、5#引腳、6#引腳分別為GND、VDD、RXD、TXD、SDA、SCL。在六個引腳中，本項目只使用了其中的GND, VDD, SDA, and SCL四個腳。
根據(jù)數(shù)據(jù)表，TOF10120的I2C地址為0xA4，但尋址采用高7bit即0x52，這相當(dāng)于82。
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交通LED模塊
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該模塊為司機(jī)提供指示，本身帶有限流電阻，無需額外連接電阻器。
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模塊共有4個公頭，GND引腳鏈接與控制器的GND引腳，或數(shù)字引腳。這樣，5v信號將熄滅模塊，GND or LOW電平信號將啟動模塊。其中，R標(biāo)號代表紅色LED, Y標(biāo)號代表黃色LED，G標(biāo)號代表綠色LED，高電平信號時LED點(diǎn)亮。
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連接電路
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首先，按照電路圖，5V電源由LM7805三端穩(wěn)壓器提供給Arduino Nano，后面需要連接一個470uF的去耦鋁電解電容器。
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其中，5v穩(wěn)壓連接到Arduino Nano的VIN引腳，TOF10120激光測距模塊的SCL、SDA引腳分別連接于Arduino板子的A5、A4引腳，電源線鏈接于Arduino板子的5V和接地引腳。
信號燈LED模塊的GND引腳鏈接到Arduino板子的5號引腳，紅色LED鏈接到Arduino的4號引腳，黃色LED連接到3號引腳，綠色LED連接到2號引腳。
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PCB設(shè)計
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接下來，設(shè)計Arduino Nano PCB開發(fā)板，母頭用于3.3V、12V、5V和接地，左側(cè)作為Vero板用來焊接其他電子元件，Arduino Nano的左右兩側(cè)都設(shè)計母頭來連接跳線，也可連接傳感器和電子元器件，例如TOF10120傳感器和OLED顯示模塊的I2C引腳。
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最后，將Traffic LED模塊連接于Arduino板子的5、4、3、2引腳，再用公頭連來連接TOF10120傳感器的GND、Vdd、SCL、SDA引線。
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做完上述連接后，就使用下述代碼進(jìn)行I2C尋址：
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#include
void setup()
{
Wire.begin();
Serial.begin(115200);
Serial.println("\nI2C Scanner");
}
void loop()
{
byte error, address;
int nDevices;
Serial.println("Scanning...");
nDevices = 0;
for(address = 0; address <= 127; address++ )
{
Wire.beginTransmission(address);
error = Wire.endTransmission();
if (error == 0)
{
Serial.print("I2C device found at address 0x");
if (address<16)
Serial.print("0");
Serial.print(address, HEX);
Serial.println(" !");
nDevices++;
}
else if (error==4)
{
Serial.print("Unknow error at address 0x");
if (address<16)
Serial.print("0");
Serial.println(address,HEX);
}
}
if (nDevices == 0)
Serial.println("No I2C devices found\n");
else
Serial.println("done\n");
delay(30000);
}
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#include
void setup()
{
Wire.begin();
Serial.begin(115200);
Serial.println("\nI2C Scanner");
}
void loop()
{
byte error, address;
int nDevices;
Serial.println("Scanning...");
nDevices = 0;
for(address = 0; address <= 127; address++ )
{
Wire.beginTransmission(address);
error = Wire.endTransmission();
if (error == 0)
{
Serial.print("I2C device found at address 0x");
if (address<16)
Serial.print("0");
Serial.print(address, HEX);
Serial.println(" !");
nDevices++;
}
else if (error==4)
{
Serial.print("Unknow error at address 0x");
if (address<16)
Serial.print("0");
Serial.println(address,HEX);
}
}
if (nDevices == 0)
Serial.println("No I2C devices found\n");
else
Serial.println("done\n");
delay(30000);
}
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上述代碼上傳完成后，打開serial monitor就會看到TOF10120激光傳感器的I2C地址。按照數(shù)據(jù)手冊，TOF10120模塊的I2C地址為0xA4，由于其尋址采用了高7 bits，這樣就變成了0x52，相當(dāng)于82。
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至此，大家已經(jīng)知道了i2c地址，可以把TOF10120測距傳感器模塊固定到板子上了。該傳感器須固定到適當(dāng)?shù)母叨龋?a target="_blank">檢測車輛和距離。這當(dāng)然不難，你可以豎一個底部帶有螺絲的膠塊，我為了方便站了一個充電器的外殼，只要高度滿足即可。
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下面是本項目的代碼，我是按照裁剪的墊子大小來寫的，這個尺寸正好就是停車區(qū)域的大小。
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/* Smart Car Parking system Code
* In this project the TOF10120 Laser Distance Sensor is used for measuring the distance.
*/
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#include
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// Traffic LED Module interfacing with Arduino Uno or Arduino Nano
int GND_PIN = 5;
int RED_PIN = 4;
int YELLOW_PIN = 3;
int GREEN_PIN = 2;
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unsigned char ok_flag;
unsigned char fail_flag;
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unsigned short lenth_val = 0;
unsigned char i2c_rx_buf[16];
unsigned char dirsend_flag=0;
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int x_mm; // distance in millimeters
float y_inches; // distance in inches
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void setup() {
Wire.begin();
Serial.begin(9600,SERIAL_8N1);
printf_begin();
pinMode(GND_PIN, OUTPUT);
pinMode(RED_PIN, OUTPUT);
pinMode(YELLOW_PIN, OUTPUT);
pinMode(GREEN_PIN, OUTPUT);
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digitalWrite(GND_PIN, LOW);
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
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}
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void loop() {
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x_mm = ReadDistance();
// Serial.print(x_mm);
// Serial.println(" mm");
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// You can convert millimeters to inches in one of two ways: divide the number of millimeters by 25.4, or multiply the number of millimeters by 0.0394
y_inches = x_mm * 0.0394;
// Serial.print(y_inches);
// Serial.println(" inches");
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if ( (y_inches > 0) && (y_inches <= 3) )
{
digitalWrite(RED_PIN, HIGH);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
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if ( (y_inches > 3) && (y_inches <= 6) )
{
digitalWrite(RED_PIN, HIGH);
delay(200);
digitalWrite(RED_PIN, LOW);
delay(200);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
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if ( (y_inches > 6) && (y_inches <= 10) )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, HIGH);
digitalWrite(GREEN_PIN, LOW);
}
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if ( (y_inches > 10) && (y_inches <= 20) )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, HIGH);
}
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if ( y_inches > 20 )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
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if ( y_inches < 0 )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
}
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int serial_putc( char c, struct __file * )
{
Serial.write( c );
return c;
}
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void printf_begin(void)
{
fdevopen( &serial_putc, 0 );
}
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void SensorRead(unsigned char addr,unsigned char* datbuf,unsigned char cnt)
{
unsigned short result=0;
// step 1: instruct sensor to read echoes
Wire.beginTransmission(82); // transmit to device #82 (0x52), you can also find this address using the i2c_scanner code, which is available on electroniclinic.com
// the address specified in the datasheet is 164 (0xa4)
// but i2c adressing uses the high 7 bits so it's 82
Wire.write(byte(addr)); // sets distance data address (addr)
Wire.endTransmission(); // stop transmitting
// step 2: wait for readings to happen
delay(1); // datasheet suggests at least 30uS
// step 3: request reading from sensor
Wire.requestFrom(82, cnt); // request cnt bytes from slave device #82 (0x52)
// step 5: receive reading from sensor
if (cnt <= Wire.available()) { // if two bytes were received
*datbuf++ = Wire.read(); // receive high byte (overwrites previous reading)
*datbuf++ = Wire.read(); // receive low byte as lower 8 bits
}
}
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int ReadDistance(){
SensorRead(0x00,i2c_rx_buf,2);
lenth_val=i2c_rx_buf[0];
lenth_val=lenth_val<<8;
lenth_val|=i2c_rx_buf[1];
delay(300);
return lenth_val;
}
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/* Smart Car Parking system Code
* In this project the TOF10120 Laser Distance Sensor is used for measuring the distance.
*/
#include
// Traffic LED Module interfacing with Arduino Uno or Arduino Nano
int GND_PIN = 5;
int RED_PIN = 4;
int YELLOW_PIN = 3;
int GREEN_PIN = 2;
unsigned char ok_flag;
unsigned char fail_flag;
unsigned short lenth_val = 0;
unsigned char i2c_rx_buf[16];
unsigned char dirsend_flag=0;
int x_mm; // distance in millimeters
float y_inches; // distance in inches
void setup() {
Wire.begin();
Serial.begin(9600,SERIAL_8N1);
printf_begin();
pinMode(GND_PIN, OUTPUT);
pinMode(RED_PIN, OUTPUT);
pinMode(YELLOW_PIN, OUTPUT);
pinMode(GREEN_PIN, OUTPUT);
digitalWrite(GND_PIN, LOW);
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
void loop() {
x_mm = ReadDistance();
// Serial.print(x_mm);
// Serial.println(" mm");
// You can convert millimeters to inches in one of two ways: divide the number of millimeters by 25.4, or multiply the number of millimeters by 0.0394
y_inches = x_mm * 0.0394;
// Serial.print(y_inches);
// Serial.println(" inches");
if ( (y_inches > 0) && (y_inches <= 3) )
{
digitalWrite(RED_PIN, HIGH);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
if ( (y_inches > 3) && (y_inches <= 6) )
{
digitalWrite(RED_PIN, HIGH);
delay(200);
digitalWrite(RED_PIN, LOW);
delay(200);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
if ( (y_inches > 6) && (y_inches <= 10) )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, HIGH);
digitalWrite(GREEN_PIN, LOW);
}
if ( (y_inches > 10) && (y_inches <= 20) )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, HIGH);
}
if ( y_inches > 20 )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
if ( y_inches < 0 )
{
digitalWrite(RED_PIN, LOW);
digitalWrite(YELLOW_PIN, LOW);
digitalWrite(GREEN_PIN, LOW);
}
}
int serial_putc( char c, struct __file * )
{
Serial.write( c );
return c;
}
void printf_begin(void)
{
fdevopen( &serial_putc, 0 );
}
void SensorRead(unsigned char addr,unsigned char* datbuf,unsigned char cnt)
{
unsigned short result=0;
// step 1: instruct sensor to read echoes
Wire.beginTransmission(82); // transmit to device #82 (0x52), you can also find this address using the i2c_scanner code, which is available on electroniclinic.com
// the address specified in the datasheet is 164 (0xa4)
// but i2c adressing uses the high 7 bits so it's 82
Wire.write(byte(addr)); // sets distance data address (addr)
Wire.endTransmission(); // stop transmitting
// step 2: wait for readings to happen
delay(1); // datasheet suggests at least 30uS
// step 3: request reading from sensor
Wire.requestFrom(82, cnt); // request cnt bytes from slave device #82 (0x52)
// step 5: receive reading from sensor
if (cnt <= Wire.available()) { // if two bytes were received
*datbuf++ = Wire.read(); // receive high byte (overwrites previous reading)
*datbuf++ = Wire.read(); // receive low byte as lower 8 bits
}
}
int ReadDistance(){
SensorRead(0x00,i2c_rx_buf,2);
lenth_val=i2c_rx_buf[0];
lenth_val=lenth_val<<8;
lenth_val|=i2c_rx_buf[1];
delay(300);
return lenth_val;
}
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上面是編程代碼，前提是已經(jīng)下載了 Wire.h 庫文件，代碼中的距離單位為英寸，歡迎實踐和分享。
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