Fundamental:
This article provides a general overview of Maxim’s 1-Wire® technology, its communication concept and the benefit of low pin count package options. The main section discusses 1-Wire devices by their feature set and explains the typical applications. The article concludes with practical information on how to evaluate 1-Wire devices, explains device customization options, and references resources that assist customers with integration of 1-Wire technology in their systems.
Purpose:
1-Wire communication is a protocol operating through one wire between the controller device and the peripheral device. This article covers the basics of using the 1-Wire protocol with an ESP32 with the help of the OneWire library. The following sections provide information about the 1-Wire protocol, interface, power, addressing devices, reading devices and finally a short glimpse into the library's history.
DS18B20 introduce:
The DS18B20 temperature sensor is widely used in electronic projects that uses a single wire to acquire data, therefore claiming it as single wire programmable in nature. It uses a single GPIO pin of the microcontroller to output the current temperature reading of its surroundings. By using the least number of pins, we can conveniently access multiple temperature readings by hooking up DS18B20 sensors on the same GPIO pin.
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ESP32 Code Introduce:
#include <OneWire.h>
#include <DallasTemperature.h>
//--------- Flag structure --------------------------------------
typedef struct _vFlag
{
uint8_t BTFlag = 0;
uint8_t DC_Flag = 0;
uint8_t CANFlag = 0;
uint8_t I2C_Flag = 0;
uint8_t BMP180Flag = 0;
uint8_t DS18B20Flag = 0;
uint8_t JSONFlag = 0;
uint8_t Radar_L_Flag = 0;
uint8_t Radar_R_Flag = 0;
uint8_t sensor_Flag = 0;
uint8_t sensor1_Flag = 0;
uint8_t initial_Flag = 0;
uint8_t Tone_Flag = -1;
uint8_t IR_RECV_Flag=0;
uint8_t IR_SEND_Flag=0;
uint8_t FunctionFlag = 3;
uint8_t SendFlag = 0;
uint8_t BMPCnt = 0;
} vFlag;
vFlag *flag_Ptr;
vFlag flag;
//----- DS18B20 ------------------
#define DQ_Pin 4
OneWire oneWire(DQ_Pin);
DallasTemperature sensors(&oneWire);
byte data[12]; // buffer for data
byte address[8]; // 64 bit device address
//----------uart--------------
#define LINE_BUFFER_LENGTH 64
//--------- uart structure --------------------------------------
typedef struct _vUart
{
char c;
int lineIndex = 0;
int line1Index = 0;
int BTlineIndex = 0;
bool lineIsComment;
bool lineSemiColon;
//char *line;
char line[128];
//char line1[128];
char BTline[20];
//char R_line[20];
//char L_line[20];
String inputString;
String BTinputString;
String S1inputString;
int V[16];
char ctemp[30];
char I2C_Data[80];
int DC_Spped = 50;
float Voltage[16];
int Buffer[128];
int StartCnt = 0;
int ReadCnt = 0;
int sensorValue = 0;
} vUart;
vUart *Uart_Ptr;
vUart Uart;
//-------------------------------------------------
void setup()
{
Serial.begin(9600);
Serial.println(F("init"));
if (oneWire.search(address))
{
Serial.println("Slave device found!");
Serial.print("Device Address = ");
Serial.println(address[0]);
}
else
{
Serial.println("Slave device not found!");
}
//-----DS-----------
sensors.begin();
}
//-----------------------------------------
void loop()
{
Serial.print(F("Main at core:"));
Serial.println(xPortGetCoreID());
while(1)
{
while (Serial.available() > 0)
{
Uart.c = Serial.read();
if ((Uart.c == '\n') || (Uart.c == '\r'))
{ // End of line reached
if (Uart.lineIndex > 0)
{ // Line is complete. Then execute!
Uart.line[Uart.lineIndex] = '\0'; // Terminate string
//Serial.println( F("Debug") );
//Serial.println( Uart.inputString );
processCommand(Uart.line); // do something with the command
//傳輸給藍芽
Uart.lineIndex = 0;
Uart.inputString = "";
}
else
{
// Empty or comment line. Skip block.
}
Uart.lineIsComment = false;
Uart.lineSemiColon = false;
Serial.println(F("ok>"));
}
else
{
//Serial.println( c );
if ((Uart.lineIsComment) || (Uart.lineSemiColon))
{
if (Uart.c == ')')
Uart.lineIsComment = false; // End of comment. Resume line.
}
else
{
if (Uart.c == '/')
{ // Block delete not supported. Ignore character.
}
else if (Uart.c == '~')
{ // Enable comments flag and ignore all characters until ')' or EOL.
Uart.lineIsComment = true;
}
else if (Uart.c == ';')
{
Uart.lineSemiColon = true;
}
else if (Uart.lineIndex >= LINE_BUFFER_LENGTH - 1)
{
Serial.println("ERROR - lineBuffer overflow");
Uart.lineIsComment = false;
Uart.lineSemiColon = false;
}
else if (Uart.c >= 'a' && Uart.c <= 'z')
{ // Upcase lowercase
Uart.line[Uart.lineIndex] = Uart.c - 'a' + 'A';
Uart.lineIndex = Uart.lineIndex + 1;
Uart.inputString += (char)(Uart.c - 'a' + 'A');
}
else
{
Uart.line[Uart.lineIndex] = Uart.c;
Uart.lineIndex = Uart.lineIndex + 1;
Uart.inputString += Uart.c;
}
}
}
} //while (Serial.available() > 0)
if(flag.DS18B20Flag == 1)
{
vDS18B20Task();
}
}
}
//----------------------------------------
void processCommand(char *data)
{
int len, xlen, ylen, zlen, alen;
int tempDIO;
String stemp;
len = Uart.inputString.length();
//---------------------------------------
if (strstr(data, "VER") != NULL)
{
Serial.println(F("ESP32_20230710"));
}
if (strstr(data, "DS18B20_ON") != NULL)
{
flag.DS18B20Flag = 1;
Serial.println(F("DS18B20_ON"));
}
if (strstr(data, "DS18B20_OFF") != NULL)
{
flag.DS18B20Flag = 0;
Serial.println(F("DS18B20_OFF"));
}
}
//-----------------------------------------
//-------------------------------------------
void vDS18B20Task()
{
Serial.print("Temperatures --> ");
sensors.requestTemperatures();
Serial.println(sensors.getTempCByIndex(0));
//flag.DS18B20Flag = 0;
}
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