Hi everyone, total newbie to programming here but can take instructions well. I found a simple sketch for an ESP32 board to use up to four MAX6675 boards to emulate an Arduino with a TC4 (four channel thermocouple shield initially conceived for coffee roasting) but the TC4 isn't bulletproof and on the expensive side. I managed to wire up the hardware and got it working but I also happen to already have two MAX31865 boards on hand and there are plenty of praises about how RTDs beat thermocouples in most ways so I was wondering how difficult would it be to swap the MAX6675 library reference and related code to utilise a MAX31865 library and relevant code?
The code is below but unfortunately my ability in coding is only to remove the MAX6675 library reference and include the MAX31865 one from Adafruit although I'm using cheap Chinese MAX31865 boards.
#include <SerialCommands.h> // https://github.com/ppedro74/Arduino-SerialCommands
#include <BluetoothSerial.h> // Classic Bluetooth
#include <DHT.h> // DHT22
#include <Adafruit_MAX31865.h>
//#include <SPI.h> // MAX6675 over hardware SPI
// Bluetooth
#define ESP32_RTD_BLUETOOTH_NAME "U.A.F. Mk. 2" //Bluetooth device name
BluetoothSerial SerialBT;
// DHT22
#define DHTPIN 22 // GPIO22 -> DHT22 Output
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);
double humidity;
double ambientc;
double ambientf;
// MAX6675
#define TC1_CS 32 // GPIO32 -> CS MAX6675[TC1]
#define TC2_CS 33 // GPIO33 -> CS MAX6675[TC2]
#define TC3_CS 25 // GPIO25 -> CS MAX6675[TC3]
#define TC4_CS 26 // GPIO26 -> CS MAX6675[TC4]
/* Note: All MAX6675
* MAX6675 to EPS32
* VCC -> 3.3V
* GND -> GND
* SCK -> GPIO18/CLK
* SO -> GPIO19/MISO
*/
bool unit_F = false;
#define SMA 5
int sma_idx = 0;
bool sma_filled = false;
double tc1s[SMA], tc2s[SMA], tc3s[SMA], tc4s[SMA];
double tc1, tc2, tc3, tc4;
// DHT22
void readDHT(){
float h = dht.readHumidity();
float c = dht.readTemperature();
float f = dht.readTemperature(true);
if(!isnan(h)){
humidity = h;
}
if(!isnan(c)){
ambientc = c;
}
if(!isnan(f)){
ambientf = f;
}
}
// MAX6675
double readCelsius(uint8_t cs) {
uint16_t v;
digitalWrite(cs, LOW);
v = SPI.transfer(0x00);
v <<= 8;
v |= SPI.transfer(0x00);
digitalWrite(cs, HIGH);
if (v & 0x4) {
// uh oh, no thermocouple attached!
return NAN;
}
v >>= 3;
return v*0.25;
}
double readFahrenheit(uint8_t cs) {
return readCelsius(cs) * 1.8 + 32;
}
bool readTCs(){
tc1s[sma_idx] = readCelsius(TC1_CS);
tc2s[sma_idx] = readCelsius(TC2_CS);
tc3s[sma_idx] = readCelsius(TC3_CS);
tc4s[sma_idx] = readCelsius(TC4_CS);
if(!isnan(tc1s[sma_idx]) && !isnan(tc1s[sma_idx]) && !isnan(tc1s[sma_idx]) && !isnan(tc1s[sma_idx])){
sma_idx++;
if(sma_idx >= SMA){
sma_filled = true;
sma_idx = 0;
}
tc1 = 0;
tc2 = 0;
tc3 = 0;
tc4 = 0;
if(sma_filled){
for(int i = 0; i<SMA; i++){
tc1 += tc1s[i];
tc2 += tc2s[i];
tc3 += tc3s[i];
tc4 += tc4s[i];
}
tc1 /= SMA;
tc2 /= SMA;
tc3 /= SMA;
tc4 /= SMA;
}
return true;
}
return false;
}
// USB & Bluetooth SerialCommands
char serialbt_cmds_buffer[32];
char serial_cmds_buffer[32];
SerialCommands serialbt_cmds(&SerialBT, serialbt_cmds_buffer, sizeof(serialbt_cmds_buffer), "\n", ";");
SerialCommands serial_cmds(&Serial, serial_cmds_buffer, sizeof(serial_cmds_buffer), "\n", ";");
//This is the default handler, and gets called when no other command matches.
void cmd_unrecognized(SerialCommands* sender, const char* cmd){
sender->GetSerial()->print("Unrecognized command [");
sender->GetSerial()->print(cmd);
sender->GetSerial()->println("]");
}
void cmdSetChannel(SerialCommands* sender){
sender->GetSerial()->println("#OK");
}
SerialCommand serialCmdSetChannel("CHAN", cmdSetChannel);
void cmdSetUnits(SerialCommands* sender){
char* units = sender->Next();
if (units[0] == 'F'){
unit_F = true;
sender->GetSerial()->println("#OK Farenheit");
}else if (units[0] == 'C'){
unit_F = false;
sender->GetSerial()->println("#OK Celsius");
}
}
SerialCommand serialCmdSetUnits("UNITS", cmdSetUnits);
void cmdSetFilter(SerialCommands* sender){
sender->GetSerial()->println("#OK");
}
SerialCommand serialCmdSetFilter("FILT", cmdSetFilter);
void cmdRead(SerialCommands* sender){
readDHT();
if(unit_F){
sender->GetSerial()->print(ambientf);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc1 * 1.8 + 32);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc2 * 1.8 + 32);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc3 * 1.8 + 32);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc4 * 1.8 + 32);
sender->GetSerial()->print(",0.00,0.00,0.00"); // Heater, Fan, PID set value
}else{
sender->GetSerial()->print(ambientc);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc1);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc2);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc3);
sender->GetSerial()->print(",");
sender->GetSerial()->print(tc4);
sender->GetSerial()->print(",0.00,0.00,0.00"); // Heater, Fan, PID set value
}
sender->GetSerial()->println("");
}
SerialCommand serialCmdRead("READ", cmdRead);
void setup(){
// DHT22 for ambient and humidity
pinMode(DHTPIN, INPUT);
dht.begin();
// Thermocouple (MAX6675 x4 over hardware SPI)
pinMode(TC1_CS, OUTPUT);
pinMode(TC2_CS, OUTPUT);
pinMode(TC3_CS, OUTPUT);
pinMode(TC4_CS, OUTPUT);
digitalWrite(TC1_CS, HIGH);
digitalWrite(TC2_CS, HIGH);
digitalWrite(TC3_CS, HIGH);
digitalWrite(TC4_CS, HIGH);
SPI.begin();
SPI.beginTransaction (SPISettings (1000000, MSBFIRST, SPI_MODE0));
// USB Serial
Serial.begin(115200);
serial_cmds.SetDefaultHandler(cmd_unrecognized);
serial_cmds.AddCommand(&serialCmdSetChannel);
serial_cmds.AddCommand(&serialCmdSetUnits);
serial_cmds.AddCommand(&serialCmdSetFilter);
serial_cmds.AddCommand(&serialCmdRead);
// Bluetooth Serial
SerialBT.begin(ROAST_ESP32_BLUETOOTH_NAME);
serialbt_cmds.SetDefaultHandler(cmd_unrecognized);
serialbt_cmds.AddCommand(&serialCmdSetChannel);
serialbt_cmds.AddCommand(&serialCmdSetUnits);
serialbt_cmds.AddCommand(&serialCmdSetFilter);
serialbt_cmds.AddCommand(&serialCmdRead);
sma_idx = 0;
sma_filled = true;
tc1 = 0;
tc2 = 0;
tc3 = 0;
tc4 = 0;
}
void loop(){
serialbt_cmds.ReadSerial();
serial_cmds.ReadSerial();
if(readTCs()){
delay(200);
}
}
