I am using the following code (from atlas scientific do data sheet)
//**THIS CODE WILL WORK ON ANY ARDUINO**
//This code was written to be easy to understand.
//Modify this code as you see fit.
//This code will output data to the Arduino serial monitor.
//Type commands into the Arduino serial monitor to control the D.O. circuit.
//An Arduino UNO was used to test this code.
//This code was written in the Arduino 1.8.5 IDE
//This code was last tested 1/2018
#include <Wire.h> //enable I2C.
#define address 97 //default I2C ID number for EZO D.O. Circuit.
char computerdata[20]; //we make a 20 byte character array to hold incoming data from a pc/mac/other.
byte received_from_computer = 0; //we need to know how many characters have been received.
byte code = 0; //used to hold the I2C response code.
char DO_data[20]; //we make a 20 byte character array to hold incoming data from the D.O. circuit.
byte in_char = 0; //used as a 1 byte buffer to store inbound bytes from the D.O. Circuit.
int time_ = 1000; //used to change the delay needed depending on the command sent to the EZO Class D.O. Circuit.
float DO_float; //float var used to hold the float value of the DO.
char *DO; //char pointer used in string parsing.
char *sat; //char pointer used in string parsing.
float do_float; //float var used to hold the float value of the dissolved oxygen.
float sat_float; //float var used to hold the float value of the saturation percentage.
void setup() //hardware initialization.
{
Serial.begin(9600); //enable serial port.
Wire.begin(); //enable I2C port.
}
void loop() { //the main loop.
byte i = 0; //counter used for DO_data array.
if (Serial.available() > 0) { //if data is holding in the serial buffer
received_from_computer = Serial.readBytesUntil(13, computerdata, 20); //we read the data sent from the serial monitor(pc/mac/other) until we see a <CR>. We also count how many characters have been received.
computerdata[received_from_computer] = 0; //stop the buffer from transmitting leftovers or garbage.
computerdata[0] = tolower(computerdata[0]); //we make sure the first char in the string is lower case.
if (computerdata[0] == 'c' || computerdata[0] == 'R')time_ = 600; //if a command has been sent to calibrate or take a reading we wait 600ms so that the circuit has time to take the reading.
else time_ = 300; //if not 300ms will do
Wire.beginTransmission(address); //call the circuit by its ID number.
Wire.write(computerdata); //transmit the command that was sent through the serial port.
Wire.endTransmission(); //end the I2C data transmission.
if (strcmp(computerdata, "sleep") != 0) { //if the command that has been sent is NOT the sleep command, wait the correct amount of time and request data.
//if it is the sleep command, we do nothing. Issuing a sleep command and then requesting data will wake the D.O. circuit.
delay(time_); //wait the correct amount of time for the circuit to complete its instruction.
Wire.requestFrom(address, 20, 1); //call the circuit and request 20 bytes (this may be more than we need)
code = Wire.read(); //the first byte is the response code, we read this separately.
switch (code) { //switch case based on what the response code is.
case 1: //decimal 1.
Serial.println("Success"); //means the command was successful.
break; //exits the switch case.
case 2: //decimal 2.
Serial.println("Failed"); //means the command has failed.
break; //exits the switch case.
case 254: //decimal 254.
Serial.println("Pending"); //means the command has not yet been finished calculating.
break; //exits the switch case.
case 255: //decimal 255.
Serial.println("No Data"); //means there is no further data to send.
break; //exits the switch case.
}
while (Wire.available()) { //are there bytes to receive.
in_char = Wire.read(); //receive a byte.
DO_data[i] = in_char; //load this byte into our array.
i += 1; //incur the counter for the array element.
if (in_char == 0) { //if we see that we have been sent a null command.
i = 0; //reset the counter i to 0.
Wire.endTransmission(); //end the I2C data transmission.
break; //exit the while loop.
}
}
if (isDigit(DO_data[0])) {
string_pars(); //If the first char is a number we know it is a DO reading, lets parse the DO reading
}
else { //if it’s not a number
Serial.println(DO_data); //print the data.
for (i = 0; i < 20; i++) { //step through each char
DO_data[i] = 0; //set each one to 0 this clears the memory
}
}
}
}
}
void string_pars() { //this function will break up the CSV string into its 2 individual parts, DO and %sat.
byte flag = 0; //this is used to indicate is a “,” was found in the string array
byte i = 0; //counter used for DO_data array.
for (i = 0; i < 20; i++) { //Step through each char
if (DO_data[i] == ',') { //do we see a ','
flag = 1; //if so we set the var flag to 1 by doing this we can identify if the string being sent from the DO circuit is a CSV string containing tow values
}
}
if (flag != 1) { //if we see the there WAS NOT a ‘,’ in the string array
Serial.print("DO:"); //print the identifier
Serial.println(DO_data); //print the reading
}
if (flag == 1) { //if we see the there was a ‘,’ in the string array
DO = strtok(DO_data, ","); //let's pars the string at each comma
sat = strtok(NULL, ","); //let's pars the string at each comma
Serial.print("DO:"); //print the identifier
Serial.println(DO); //print the reading
Serial.print("Sat:"); //print the identifier
Serial.println(sat); //print the reading
flag = 0; //reset the flag
}
/* //uncomment this section if you want to take the ASCII values and convert them into a floating point number.
DO_float=atof(DO);
sat_float=atof(sat);
*/
}
According to the data sheet (link in post#1), for reading, 'R' needs to be sent. Is there any method that 'R' be sent in the code itself in a loop as i have to "send" 'R' and a blank "send" it in the serial monitor window every time i have to take reading and .