Hello,
I am trying to send commands to my pH stamp with my Arduino Uno with the objective of switching LEDs on/off and calibrating the probe.
When connected, it currently sends an uncalibrated pH reading to the serial monitor every second.
However, when I type any command into the serial monitor (such as L,0 to switch off the LEDs or cal,mid,7 to calibrate the probe), the device gives a *RS followed by a *RE and then continues to send uncalibrated pH readings to the serial monitor with no change to the LEDs or calibration.
According to the data sheet below, the messages indicate that the device has reset, and then booted up.
Datasheet link for an EZO pH Circuit: http://www.atlas-scientific.com/_files/_datasheets/_circuit/pH_EZO_datasheet.pdf?
The circuit was wired correctly according to Atlas Scientific's wiring diagram found here: http://www.atlas-scientific.com/_files/instructions/ezo-ph-wiringdiagram.pdf with pin 2 connected to the tx pin on the pH stamp, and pin 3 connected to the rx pin in the pH stamp.
Finally, the code I've used was copied exactly from the sample code given on the Atlas Scientific website: http://www.atlas-scientific.com/_files/code/Arduino_pH_sample_code.pdf which is inefficient, but I'd like to get it to work first before I start truncating it for myself.
Below is the code I have sent to the Arduino:
//This code will output data to the Arduino serial monitor. Type commands into the Arduino serial monitor to control the pH circuit.
//set the var Arduino_only to equal 1 to watch the Arduino take over control of the pH circuit.
//As of 11/6/14 the default baud rate has changed to 9600.
//The old default baud rate was 38400.
#include <SoftwareSerial.h> //we have to include the SoftwareSerial library, or else we can't use it.
#define rx 2 //define what pin rx is going to be.
#define tx 3 //define what pin Tx is going to be.
SoftwareSerial myserial(rx, tx); //define how the soft serial port is going to work.
char ph_data[20]; //we make a 20 byte character array to hold incoming data from the pH.
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 received_from_sensor=0; //we need to know how many characters have been received.
byte arduino_only=0; //if you would like to operate the pH Circuit with the Arduino only and not use the serial monitor to send it commands set this to 1. The data will still come out on the serial monitor, so you can see it working.
byte startup=0; //used to make sure the Arduino takes over control of the pH Circuit properly.
float ph=0; //used to hold a floating point number that is the pH.
byte string_received=0; //used to identify when we have received a string from the pH circuit.
void setup(){
Serial.begin(9600); //enable the hardware serial port
myserial.begin(9600); //enable the software serial port
}
void serialEvent(){ //this interrupt will trigger when the data coming from the serial monitor(pc/mac/other) is received.
if(arduino_only!=1){ //if Arduino_only does not equal 1 this function will be bypassed.
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; //we add a 0 to the spot in the array just after the last character we received.. This will stop us from transmitting incorrect data that may have been left in the buffer.
myserial.print(computerdata); //we transmit the data received from the serial monitor(pc/mac/other) through the soft serial port to the pH Circuit.
myserial.print('\r'); //all data sent to the pH Circuit must end with a <CR>.
}
}
void loop(){
if(myserial.available() > 0){ //if we see that the pH Circuit has sent a character.
received_from_sensor=myserial.readBytesUntil(13,ph_data,20); //we read the data sent from pH Circuit until we see a <CR>. We also count how many character have been received.
ph_data[received_from_sensor]=0; //we add a 0 to the spot in the array just after the last character we received. This will stop us from transmitting incorrect data that may have been left in the buffer.
string_received=1; //a flag used when the Arduino is controlling the pH Circuit to let us know that a complete string has been received.
Serial.println(ph_data); //lets transmit that data received from the pH Circuit to the serial monitor.
}
if(arduino_only==1){Arduino_Control();} //If the var arduino_only is set to one we will call this function. Letting the Arduino take over control of the pH Circuit
}
void Arduino_Control(){
if(startup==0){ //if the Arduino just booted up, we need to set some things up first.
myserial.print("c,0\r"); //take the pH Circuit out of continues mode.
delay(50); //on start up sometimes the first command is missed.
myserial.print("c,0\r"); //so, let’s send it twice.
delay(50); //a short delay after the pH Circuit was taken out of continues mode is used to make sure we don’t over load it with commands.
startup=1; //startup is completed, let's not do this again during normal operation.
}
delay(800); //we will take a reading ever 800ms. You can make this much longer or shorter if you like.
myserial.print("R\r"); //send it the command to take a single reading.
if(string_received==1){ //did we get data back from the ph Circuit?
ph=atof(ph_data); //many people ask us "how do I convert a string into a float?" This is how...
if(ph>=7.5){Serial.println("high\r");} //This is the proof that it has been converted into a float.
if(ph<7.5){Serial.println("low\r");} //This is the proof that it has been converted into a float.
string_received=0;} //reset the string received flag.
}
//here are some functions you might find useful
//these functions are not enabled
void cal_s(){ //calibrate to a pH of 7
myserial.print("cal,mid,7\r");} //send the "cal,mid,7" command to calibrate to a pH of 7.00
void cal_f(){ //calibrate to a pH of 4
myserial.print("cal,low,4\r");} //send the "cal,low,4" command to calibrate to a pH of 4.00
void cal_t(){ //calibrate to a pH of 10.00
myserial.print("cal,high,10\r");} //send the "cal,high,10" command to calibrate to a pH of 10.00
void phFactoryDefault(){ //factory defaults the pH circuit
myserial.print("X\r");} //send the "X" command to factory reset the device
void read_info(){ //get device info
myserial.print("I\r");} //send the "I" command to query the information
void phSetLEDs(byte enabled) //turn the LEDs on or off
{
if(enabled) //if enabled is > 0
myserial.print("L,1\r"); //the LED's will turn ON
else //if enabled is 0
myserial.print("L,0\r"); //the LED's will turn OFF
}
Please find below a previous post on a similar issue with the pH stamp and serial monitor:
http://forum.arduino.cc/index.php?topic=294120.0
Any assistance on getting the pH circuit to respond to commands sent by the serial monitor for calibration would be greatly appreciated.
Thanks in advance!