UnoTC4.ino

/*
 * TC4 Simulator for Artisan Coffee Roaster Application
 *
 * Released under MIT License
 *
 * Created by Sam Chen on 2020
 * Copyright (c) 2020 sam4sharing.com, All rights reserved.
 * 
 * Blog     : https://www.sam4sharing.com
 * YouTube  : https://www.youtube.com/channel/UCN7IzeZdi7kl1Egq_a9Tb4g
 */

#include <Arduino.h>
#include <SoftwareSerial.h>
#include <MAX6675.h>
#include "SevSeg.h"

float averageTemperature ( float *);
void handleArtisanCommands( void );

#define PRINT_TEAMPERATURE_EACH_READING     1	    // Set, to print temperature vaule on serial debug port
#define PRINT_ARTISAN_WHOLE_MESSAGE	    	0       // set, to print Artisan commands on serial debug port
#define ENVIRONMENT_TEMPERATURE_EXIST       1       // Set, if you installed ET thermal couple 
#define SEGMENT_DISPLAY_EXIST               1       // Set, if you installed 7-Segment Display

#define SCK_PIN       13      // D13, PB5
#define SO_PIN 	      12      // D12, PB4
#define CS_BT_PIN     10      // D10, PB2
#define CS_ET_PIN     9       // D9,  PB1
#define SOFT_TX       8       // D8,  PB0
#define SOFT_RX       7       // D7,  PD7

/* 
the default sample rate of Artisan is 3 seconds, although the setting value can be modified by user.
I think this value is generated from lots of experimental, so uses 3 seconds as our program algorithm
thus, 1) Set polling intervel 750ms and 2) Array length is 4. that is, the reported temperature is
avaraged from 4 times MAX6675 temperature reading. (750ms x 4 = 3s)
*/
#define TEMPERATURE_ARRAY_LENGTH	       	4		// for averagging temperature purpose
#define INTERVEL 							750		// read MAX6675 value every "INTERVEL" ms
float   	BT_TempArray[TEMPERATURE_ARRAY_LENGTH];	// temperature array
int			BT_ArrayIndex = 0;                      // A pointer of temperature array
float		BT_CurTemp, BT_AvgTemp;

bool		isReady = false;                      	// flag for temperature array ready for reading
bool 		unit_C = true;                          // indicate temperature unit from Artisan requested 

#define ABNORMAL_TEMPERATURE_DEGREE         10      // A arrange for abnormal temperature value
bool		abnormalValue = false;                  // indicate temperature value is unexpect or not

unsigned long 	previousMillis = 0;    	           	// store last time of temperature reading

// Create objects for Beam Temperature (BT) and Environment Temperature (ET)
MAX6675 BT_Thermocouple(CS_BT_PIN);

// Variables for Environment Temperature if exist
#if ENVIRONMENT_TEMPERATURE_EXIST
float		ET_CurTemp = 0.0;
MAX6675 ET_Thermocouple(CS_ET_PIN);
#endif

#if SEGMENT_DISPLAY_EXIST
// Create object for a seven segment controller
SevSeg sevseg; 
#endif

// Create Software Serial port for debugging purpose
SoftwareSerial SerialDebug(SOFT_RX, SOFT_TX);		// RX, TX : D7, D8

void setup() {

#if SEGMENT_DISPLAY_EXIST
  byte numDigits = 3;   
  byte digitPins[] = {6, 5, 4}; 
  byte segmentPins[] = {14, 15, 16, 17, 18, 19, 2, 3}; 

  sevseg.begin(COMMON_ANODE, numDigits, digitPins, segmentPins);
  sevseg.setBrightness(100);
#endif

  // Serial ports initialize
  Serial.begin(115200);
  SerialDebug.begin(115200);
//Serial.println("On board UART2USB port is used to communicate with Artisan App");
  SerialDebug.println(" ");
  SerialDebug.println("Artisan TC4 Simulator with MAX6675 v0.02");

  previousMillis = millis();						// store current time as previousMillis
}

void loop() {

	unsigned long currentMillis = millis();			// get current time

  	// For the MAX6675 to update, 250ms delay is AT LEAST !
	// Here, we set INTERVEL (750ms) to reading per time
	if ( currentMillis - previousMillis >= INTERVEL ) {
	    // means time to read new temperature
	    previousMillis = currentMillis;

      	// read BT from MAX6675 thermal couple
      	BT_CurTemp = BT_Thermocouple.readTempC();

	    if ( isReady ) {
        	// means, first round of temperature array is done, can do averaging and filter out operation  
	    	BT_AvgTemp = averageTemperature( &BT_TempArray[0] );

        	// filter out abnormal temperature-up only, bypass temperature-down
	    	// because "CHARGE" period, the temperature-down may large than 10 degree
	    	if ( BT_CurTemp < (BT_AvgTemp + ABNORMAL_TEMPERATURE_DEGREE) ) {
	    		// temperature is in-arrange, store it
	    		BT_TempArray[BT_ArrayIndex] = BT_CurTemp;
	    	}
	    	else {
	    	  	// set abnormal flag
	    		abnormalValue = true;
	    		// print ? with temperature value in newline
          		SerialDebug.println(" ");
          		SerialDebug.print(" ?");
          		SerialDebug.println(BT_CurTemp);
	    	}
	    }
	    else {
	    	// just read current temperature in "first 10" reading
	    	BT_TempArray[BT_ArrayIndex] = BT_CurTemp;
	    }

      	if ( !abnormalValue ) {
        	// Normal temperature will into this loop
#if PRINT_TEAMPERATURE_EACH_READING
        	// print MAX6675 reading value on serial monitor
	    	if ( BT_ArrayIndex == 0 ) {
				SerialDebug.println(" ");
	    		SerialDebug.print("Temperature: ");
	    	}

        	SerialDebug.print(" ");			
	    	SerialDebug.print(BT_CurTemp);
#endif
        	BT_ArrayIndex++;
        	if ( BT_ArrayIndex >= TEMPERATURE_ARRAY_LENGTH ) {
          		BT_ArrayIndex = 0;

          		if ( !isReady ) {
            		isReady = true;
          		}
          
#if PRINT_TEAMPERATURE_EACH_READING                   
          		SerialDebug.print(" ");	
          		SerialDebug.print("Average: ");
          		SerialDebug.print(BT_AvgTemp);
#endif     
#if ENVIRONMENT_TEMPERATURE_EXIST
          		// The ET is reference temperature, don't need averaging
          		// just read ET from MAX6675 thermal couple every 3 seconds
          		ET_CurTemp = ET_Thermocouple.readTempC();
#if PRINT_TEAMPERATURE_EACH_READING           
          		SerialDebug.print(" ");	
          		SerialDebug.print("ET: ");
          		SerialDebug.print(ET_CurTemp);
#endif   
#endif
        	} 
#if SEGMENT_DISPLAY_EXIST
        	sevseg.setNumber(BT_AvgTemp);   
#endif             
      	}
      	else {
        	// After bypass abnormal value, reset flag here
	    	abnormalValue = false;
      	}
  	}

	// A handle for Artisan application command from
  	handleArtisanCommands();

#if SEGMENT_DISPLAY_EXIST
  	// Must run repeatedly; don't use blocking code (ex: delay()) in the loop() function or this won't work right
  	sevseg.refreshDisplay(); 
#endif  
}

void handleArtisanCommands() {   

    if ( Serial.available() ) {
        String msg = Serial.readStringUntil('\n');

#if PRINT_ARTISAN_WHOLE_MESSAGE
		SerialDebug.println(msg);                 			// print whole message
#endif

		if (msg.indexOf("READ")==0) {	       				// READ command
/*
	The READ command requests current temperature readings on all active channels. 
	Response from TC4 device is ambient temperature followed by a comma separated list of temperatures in current active units
	The logical channel order is : ambient,chan1,chan2,chan3,chan4
*/	
			Serial.print("0.00,");			      			// ambient temperature
#ifdef ENVIRONMENT_TEMPERATURE_EXIST    
      		if (unit_C)  
			  	Serial.print(ET_CurTemp);					// channel 1 : Environment Temperature (ET) with degree Celsius
      		else 
      			Serial.print(ET_CurTemp * 9.0/5.0 + 32);	// channel 1 : Environment Temperature (ET) with degree Farenheit
#else
      		if (unit_C)
			  	Serial.print(BT_AvgTemp);			        // channel 1 : Environment Temperature (ET); no ET sensor, so uses BT instead	
      		else
        		Serial.print(BT_AvgTemp * 9.0/5.0 + 32);	// channel 1 : Environment Temperature (ET); no ET sensor, so uses BT instead	
#endif      				 
    		Serial.print(",");		
      		if (unit_C)		
			  	Serial.print(BT_AvgTemp);	            	// channel 2 : Bean Temperature (BT) with degree Celsius
      		else 
        		Serial.print(BT_AvgTemp * 9.0/5.0 + 32);	// channel 2 : Bean Temperature (BT) with degree Farenheit 
    		Serial.println(",0.00,0.00");	          		// channel 3,4 : A vaule of zero indicates the channel is inactive
			
// The READ command be sent from Artisan every 3 seconds (set by sample rate), unmark below code carefully
//		SerialDebug.println("Artisan \"READ\"");						
    	} else if (msg.indexOf("UNITS;")== 0) {	  			// UNIT command 
      		if (msg.substring(6,7)=="F") {   
			  	unit_C = false;
        		Serial.println("#OK Farenheit");
				SerialDebug.println("Artisan \"Farenheit\"");
      		}
      		else if (msg.substring(6,7)=="C") {  
        		unit_C = true;
        		Serial.println("#OK Celsius");
			  	SerialDebug.println("Artisan \"Celsius\"");
      		}
    	} else if (msg.indexOf("CHAN;")== 0) {    			// CHAN command
      		Serial.print("#OK");
	    	SerialDebug.println("Artisan \"CHAN\"");
    	} else if (msg.indexOf("FILT;")== 0) {    			// FILT command
      		Serial.print("#OK");
			SerialDebug.println("Artisan \"FILT\"");
		} else {
		  	SerialDebug.println("Artisan Unhandle command");
			SerialDebug.println(msg);
		}
  	}
}

// A function to average temperature array which values are from MAX6675 temperature reading
float averageTemperature ( float *pTemp ) {

	float avg = *pTemp;

#if 0 
  	// Below code works on ESP32 and ESP8266 but get OVF error on UNO,
  	// I think this is because UNO is 8-bit microcontroller
  	pTemp++;
  	for (int i=0; i<=(TEMPERATURE_ARRAY_LENGTH-1); i++) {
		avg = avg + *pTemp;
    	avg =  avg / 2;
    	pTemp++;
	}
#else
  	pTemp++;
	avg = avg + *pTemp;
  	avg =  avg / 2;
  	pTemp++;
	avg = avg + *pTemp;
  	avg =  avg / 2;
  	pTemp++;
	avg = avg + *pTemp;
  	avg =  avg / 2;
#endif  

	return avg;
}