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astrosloth.ino
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/*******************************************************************************
Title: Astrosloth Reflow Controller
Version: 1.00
Date: 08-19-2019
Author: Astrosloth
Brief
=====
The AstroSloth Reflow Oven Controller is an ATMEGA328 microcontroller
based system that automates your toaster oven to reflow your DIY SMT PCB projects.
With two profiles stored, you can choose between lead-based and SnAgCu based solder.
The firmware was modified from the original Rocketscream Electronics Tiny Reflow controller code written by Lim Phang Moh.
Disclaimer
==========
Please note that while the board works with DC voltages, mains power voltages are involved during oven use.
High voltages can be lethal and in the worst case may lead to electrocution and possible death.
If you are unsure of how to connect the device to mains voltage, please first contact and speak to a licensed electrician who can help you.
Use of the Astrosloth Reflow Controller is entirely at your own risk, for which we shall not be liable.
Licences
========
This Tiny Reflow Controller hardware and firmware are released under the
Creative Commons Share Alike v3.0 license
http://creativecommons.org/licenses/by-sa/3.0/
You are free to take this piece of code, use it and modify it.
All we ask is attribution including the supporting libraries used in this
firmware.
Required Libraries
==================
- Arduino PID Library:
>> https://github.com/br3ttb/Arduino-PID-Library
- Adafruit MAX31855 Library:
>> https://github.com/adafruit/Adafruit_MAX31855
- Adafruit SSD1306 Library:
>> https://github.com/adafruit/Adafruit_SSD1306
- Adafruit GFX Library:
>> https://github.com/adafruit/Adafruit-GFX-Library
Revision Description
======== ===========
1.00 Initial public release:
- Based on ATMega328 5V @ 16MHz
- Uses SSD1306 128x64 Monochrome display
*******************************************************************************/
// ***** INCLUDES *****
#include <SPI.h>
#include <Wire.h>
#include <EEPROM.h>
#include <LiquidCrystal.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_MAX31855.h>
#include <PID_v1.h>
// ***** STATE TYPE DEFINITIONS *****
typedef enum REFLOW_STATE
{
REFLOW_STATE_IDLE, //orange
REFLOW_STATE_PREHEAT, //yellow
REFLOW_STATE_SOAK, //green
REFLOW_STATE_REFLOW, // bright green
REFLOW_STATE_COOL, //blue
REFLOW_STATE_COMPLETE, //indigo
REFLOW_STATE_TOO_HOT, //violet
REFLOW_STATE_ERROR //red
} reflowState_t;
typedef enum REFLOW_STATUS
{
REFLOW_STATUS_OFF,
REFLOW_STATUS_ON
} reflowStatus_t;
typedef enum SWITCH
{
SWITCH_NONE,
SWITCH_1,
SWITCH_2
} switch_t;
typedef enum DEBOUNCE_STATE
{
DEBOUNCE_STATE_IDLE,
DEBOUNCE_STATE_CHECK,
DEBOUNCE_STATE_RELEASE
} debounceState_t;
typedef enum REFLOW_PROFILE
{
REFLOW_PROFILE_LEADFREE,
REFLOW_PROFILE_LEADED
} reflowProfile_t;
// ***** CONSTANTS *****
// ***** GENERAL PROFILE CONSTANTS *****
#define PROFILE_TYPE_ADDRESS 0
#define TEMPERATURE_ROOM 50
#define TEMPERATURE_SOAK_MIN 150
#define TEMPERATURE_COOL_MIN 100
#define SENSOR_SAMPLING_TIME 1000
#define SOAK_TEMPERATURE_STEP 5
// ***** LEAD FREE PROFILE CONSTANTS *****
#define TEMPERATURE_SOAK_MAX_LF 200
#define TEMPERATURE_REFLOW_MAX_LF 250
#define SOAK_MICRO_PERIOD_LF 9000
// ***** LEADED PROFILE CONSTANTS *****
#define TEMPERATURE_SOAK_MAX_PB 180
#define TEMPERATURE_REFLOW_MAX_PB 224
#define SOAK_MICRO_PERIOD_PB 10000
// ***** SWITCH SPECIFIC CONSTANTS *****
#define DEBOUNCE_PERIOD_MIN 100
// ***** DISPLAY SPECIFIC CONSTANTS *****
#define UPDATE_RATE 100
#define SCREEN_WIDTH 128 // display display width, in pixels
#define SCREEN_HEIGHT 64 // display display height, in pixels
#define X_AXIS_START 18 // X-axis starting position
// ***** PID PARAMETERS *****
// ***** PRE-HEAT STAGE *****
#define PID_KP_PREHEAT 100
#define PID_KI_PREHEAT 0.025
#define PID_KD_PREHEAT 20
// ***** SOAKING STAGE *****
#define PID_KP_SOAK 300
#define PID_KI_SOAK 0.05
#define PID_KD_SOAK 250
// ***** REFLOW STAGE *****
#define PID_KP_REFLOW 300
#define PID_KI_REFLOW 0.05
#define PID_KD_REFLOW 350
#define PID_SAMPLE_TIME 1000
// ***** LCD MESSAGES *****
const char* lcdMessagesReflowStatus[] = {
"Ready",
"PreHeat",
"Soak",
"Reflow",
"Cool",
"Done!",
"Hot!",
"Error"
};
// ***** DEGREE SYMBOL FOR LCD *****
unsigned char degree[8] = {
140, 146, 146, 140, 128, 128, 128, 128
};
// ***** PIN ASSIGNMENT *****
unsigned char ssrPin = 5;
unsigned char fanPin = A1;
unsigned char buzzerPin = 6;
unsigned char switchStartStopPin = A0;
unsigned char switchLfPbPin = A2;
#define ledPin A6
#define display_MOSI 11
#define display_CLK 13
#define display_DC 10
#define display_CS 8
#define display_RESET 7
#define MAXDO 4
#define MAXCS 2
#define MAXCLK 3
// ***** PID CONTROL VARIABLES *****
double setpoint;
double input;
double output;
double kp = PID_KP_PREHEAT;
double ki = PID_KI_PREHEAT;
double kd = PID_KD_PREHEAT;
int windowSize;
unsigned long windowStartTime;
unsigned long nextCheck;
unsigned long nextRead;
unsigned long updateLcd;
unsigned long timerSoak;
unsigned long buzzerPeriod;
unsigned char soakTemperatureMax;
unsigned char reflowTemperatureMax;
unsigned long soakMicroPeriod;
// Reflow oven controller state machine state variable
reflowState_t reflowState;
// Reflow oven controller status
reflowStatus_t reflowStatus;
// Reflow profile type
reflowProfile_t reflowProfile;
// Switch debounce state machine state variable
debounceState_t debounceState;
// Switch debounce timer
long lastDebounceTime;
// Switch press status
switch_t switchStatus;
switch_t switchValue;
switch_t switchMask;
// Seconds timer
unsigned int timerSeconds;
// Thermocouple fault status
unsigned char fault;
unsigned int timerUpdate;
unsigned char temperature[SCREEN_WIDTH - X_AXIS_START];
unsigned char x;
// PID control interface
PID reflowOvenPID(&input, &output, &setpoint, kp, ki, kd, DIRECT);
//OLED DISPLAY SETUP
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, display_RESET);
// MAX31855 thermocouple interface
Adafruit_MAX31855 thermocouple(MAXCLK, MAXCS, MAXDO);
void setup()
{
// Check current selected reflow profile
unsigned char value = EEPROM.read(PROFILE_TYPE_ADDRESS);
if ((value == 0) || (value == 1))
{
// Valid reflow profile value
reflowProfile = value;
}
else
{
// Default to lead-free profile
EEPROM.write(PROFILE_TYPE_ADDRESS, 0);
reflowProfile = REFLOW_PROFILE_LEADFREE;
}
// SSR pin initialization to ensure reflow oven is off
digitalWrite(ssrPin, LOW);
pinMode(ssrPin, OUTPUT);
// Buzzer pin initialization to ensure annoying buzzer is off
digitalWrite(buzzerPin, LOW);
pinMode(buzzerPin, OUTPUT);
// LED pins initialization and turn on upon start-up (active high)
//pinMode(ledPin, OUTPUT);
//digitalWrite(ledPin, HIGH);
// Start-up splash
digitalWrite(buzzerPin, HIGH);
display.begin(SSD1306_SWITCHCAPVCC, 0x3D);
display.display();
digitalWrite(buzzerPin, LOW);
delay(2000);
display.clearDisplay();
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0, 0);
display.println(F(" AstroSloth"));
display.println(F(" Reflow"));
display.println(F(" Controller"));
display.println();
display.println(F(" v1.00"));
display.println();
display.println(F(" 08-19-19"));
display.display();
delay(3000);
display.clearDisplay();
// Serial communication at 115200 bps
Serial.begin(115200);
// Turn off LED (active high)
//digitalWrite(ledPin, LOW);
// Set window size
windowSize = 2000;
// Initialize time keeping variable
nextCheck = millis();
// Initialize thermocouple reading variable
nextRead = millis();
// Initialize LCD update timer
updateLcd = millis();
}
void loop()
{
// Current time
unsigned long currentTime;
// Time to read thermocouple?
if (millis() > nextRead)
{
// Read thermocouple next sampling period
nextRead += SENSOR_SAMPLING_TIME;
// Read current temperature
input = thermocouple.readCelsius();
// If any thermocouple fault is detected
if (isnan(input))
{
// Illegal operation
reflowState = REFLOW_STATE_ERROR;
reflowStatus = REFLOW_STATUS_OFF;
Serial.println(F("Error"));
}
}
if (millis() > nextCheck)
{
// Check input in the next seconds
nextCheck += SENSOR_SAMPLING_TIME;
// If reflow process is on going
if (reflowStatus == REFLOW_STATUS_ON)
{
// Toggle red LED as system heart beat
//digitalWrite(ledPin, !(digitalRead(ledPin)));
// Increase seconds timer for reflow curve plot
timerSeconds++;
// Send temperature and time stamp to serial
Serial.print(timerSeconds);
Serial.print(F(","));
Serial.print(setpoint);
Serial.print(F(","));
Serial.print(input);
Serial.print(F(","));
Serial.println(output);
}
else
{
// Turn off red LED
//digitalWrite(ledPin, LOW);
}
}
if (millis() > updateLcd)
{
// Update LCD in the next 100 ms
updateLcd += UPDATE_RATE;
display.clearDisplay();
display.setTextSize(2);
display.setCursor(0, 0);
display.print(lcdMessagesReflowStatus[reflowState]);
display.setTextSize(1);
display.setCursor(115, 0);
if (reflowProfile == REFLOW_PROFILE_LEADFREE)
{
display.print(F("LF"));
}
else
{
display.print(F("PB"));
}
// Temperature markers
display.setCursor(0, 18);
display.print(F("250"));
display.setCursor(0, 36);
display.print(F("150"));
display.setCursor(0, 54);
display.print(F("50"));
// Draw temperature and time axis on monochrome display
display.drawLine(18, 18, 18, 63, WHITE);
display.drawLine(18, 63, 127, 63, WHITE);
display.setCursor(115, 0);
// If currently in error state
if (reflowState == REFLOW_STATE_ERROR)
{
display.setCursor(80, 9);
display.print(F("TC Error"));
}
else
{
// Right align temperature reading
if (input < 10) display.setCursor(91, 9);
else if (input < 100) display.setCursor(85,9);
else display.setCursor(80, 9);
// Display current temperature
display.print(input);
display.print((char)247);
display.print(F("C"));
}
if (reflowStatus == REFLOW_STATUS_ON)
{
// We are updating the display faster than sensor reading
if (timerSeconds > timerUpdate)
{
// Store temperature reading every 3 s
if ((timerSeconds % 3) == 0)
{
timerUpdate = timerSeconds;
unsigned char averageReading = map(input, 0, 250, 63, 19);
if (x < (SCREEN_WIDTH - X_AXIS_START))
{
temperature[x++] = averageReading;
}
}
}
}
unsigned char timeAxis;
for (timeAxis = 0; timeAxis < x; timeAxis++)
{
display.drawPixel(timeAxis + X_AXIS_START, temperature[timeAxis], WHITE);
}
// Update screen
display.display();
}
// Reflow oven controller state machine
switch (reflowState)
{
case REFLOW_STATE_IDLE:
// If oven temperature is still above room temperature
if (input >= TEMPERATURE_ROOM)
{
reflowState = REFLOW_STATE_TOO_HOT;
}
else
{
// If switch is pressed to start reflow process
if (switchStatus == SWITCH_1)
{
// Send header for CSV file
Serial.println(F("Time,Setpoint,Input,Output"));
// Intialize seconds timer for serial debug information
timerSeconds = 0;
// Initialize reflow plot update timer
timerUpdate = 0;
for (x = 0; x < (SCREEN_WIDTH - X_AXIS_START); x++)
{
temperature[x] = 0;
}
// Initialize index for average temperature array used for reflow plot
x = 0;
// Initialize PID control window starting time
windowStartTime = millis();
// Ramp up to minimum soaking temperature
setpoint = TEMPERATURE_SOAK_MIN;
// Load profile specific constant
if (reflowProfile == REFLOW_PROFILE_LEADFREE)
{
soakTemperatureMax = TEMPERATURE_SOAK_MAX_LF;
reflowTemperatureMax = TEMPERATURE_REFLOW_MAX_LF;
soakMicroPeriod = SOAK_MICRO_PERIOD_LF;
}
else
{
soakTemperatureMax = TEMPERATURE_SOAK_MAX_PB;
reflowTemperatureMax = TEMPERATURE_REFLOW_MAX_PB;
soakMicroPeriod = SOAK_MICRO_PERIOD_PB;
}
// Tell the PID to range between 0 and the full window size
reflowOvenPID.SetOutputLimits(0, windowSize);
reflowOvenPID.SetSampleTime(PID_SAMPLE_TIME);
// Turn the PID on
reflowOvenPID.SetMode(AUTOMATIC);
// Proceed to preheat stage
reflowState = REFLOW_STATE_PREHEAT;
}
}
break;
case REFLOW_STATE_PREHEAT:
reflowStatus = REFLOW_STATUS_ON;
// If minimum soak temperature is achieve
if (input >= TEMPERATURE_SOAK_MIN)
{
// Chop soaking period into smaller sub-period
timerSoak = millis() + soakMicroPeriod;
// Set less agressive PID parameters for soaking ramp
reflowOvenPID.SetTunings(PID_KP_SOAK, PID_KI_SOAK, PID_KD_SOAK);
// Ramp up to first section of soaking temperature
setpoint = TEMPERATURE_SOAK_MIN + SOAK_TEMPERATURE_STEP;
// Proceed to soaking state
reflowState = REFLOW_STATE_SOAK;
}
break;
case REFLOW_STATE_SOAK:
// If micro soak temperature is achieved
if (millis() > timerSoak)
{
timerSoak = millis() + soakMicroPeriod;
// Increment micro setpoint
setpoint += SOAK_TEMPERATURE_STEP;
if (setpoint > soakTemperatureMax)
{
// Set agressive PID parameters for reflow ramp
reflowOvenPID.SetTunings(PID_KP_REFLOW, PID_KI_REFLOW, PID_KD_REFLOW);
// Ramp up to first section of soaking temperature
setpoint = reflowTemperatureMax;
// Proceed to reflowing state
reflowState = REFLOW_STATE_REFLOW;
}
}
break;
case REFLOW_STATE_REFLOW:
// We need to avoid hovering at peak temperature for too long
// Crude method that works like a charm and safe for the components
if (input >= (reflowTemperatureMax - 5))
{
// Set PID parameters for cooling ramp
reflowOvenPID.SetTunings(PID_KP_REFLOW, PID_KI_REFLOW, PID_KD_REFLOW);
// Ramp down to minimum cooling temperature
setpoint = TEMPERATURE_COOL_MIN;
// Proceed to cooling state
reflowState = REFLOW_STATE_COOL;
}
break;
case REFLOW_STATE_COOL:
// If minimum cool temperature is achieved
if (input <= TEMPERATURE_COOL_MIN)
{
// Retrieve current time for buzzer usage
buzzerPeriod = millis() + 1000;
// Turn on buzzer to indicate completion
digitalWrite(buzzerPin, HIGH);
// Turn off reflow process
reflowStatus = REFLOW_STATUS_OFF;
// Proceed to reflow Completion state
reflowState = REFLOW_STATE_COMPLETE;
}
break;
case REFLOW_STATE_COMPLETE:
//play buzzer for buzzerperiod
if (millis() > buzzerPeriod)
{
// Turn off buzzer
digitalWrite(buzzerPin, LOW);
// Reflow process ended
reflowState = REFLOW_STATE_IDLE;
}
break;
case REFLOW_STATE_TOO_HOT:
// If oven temperature drops below room temperature
if (input < TEMPERATURE_ROOM)
{
// Ready to reflow
reflowState = REFLOW_STATE_IDLE;
}
break;
case REFLOW_STATE_ERROR:
// Check for thermocouple fault
double c = thermocouple.readCelsius();
// If thermocouple problem is still present - kinked, or broken, or not sitting in the terminal block correctly.
if(isnan(c))
{
// Wait until thermocouple wire is re-connected
reflowState = REFLOW_STATE_ERROR;
}
else
{
// Clear to perform reflow process
reflowState = REFLOW_STATE_IDLE;
}
break;
}
// If switch 1 is pressed
if (switchStatus == SWITCH_1)
{
// If currently reflow process is ongoing
if (reflowStatus == REFLOW_STATUS_ON)
{
// Button press is for cancelling
// Turn off reflow process NOW
reflowStatus = REFLOW_STATUS_OFF;
// Reinitialize state machine
reflowState = REFLOW_STATE_IDLE;
}
}
// Switch 2 is pressed
else if (switchStatus == SWITCH_2)
{
// Only can switch reflow profile during idle
if (reflowState == REFLOW_STATE_IDLE)
{
// Currently using lead-free reflow profile
if (reflowProfile == REFLOW_PROFILE_LEADFREE)
{
// Switch to leaded reflow profile
reflowProfile = REFLOW_PROFILE_LEADED;
EEPROM.write(PROFILE_TYPE_ADDRESS, 1);
}
// Currently using leaded reflow profile
else
{
// Switch to lead-free profile
reflowProfile = REFLOW_PROFILE_LEADFREE;
EEPROM.write(PROFILE_TYPE_ADDRESS, 0);
}
}
}
// Switch status has been read
switchStatus = SWITCH_NONE;
// Switch debounce state machine (analog switch)
switch (debounceState)
{
case DEBOUNCE_STATE_IDLE:
// No valid switch press
switchStatus = SWITCH_NONE;
switchValue = readSwitch();
// If either switch is pressed
if (switchValue != SWITCH_NONE)
{
// Note the pressed switch
switchMask = switchValue;
// Intialize debounce counter
lastDebounceTime = millis();
// Proceed to check validity of button press
debounceState = DEBOUNCE_STATE_CHECK;
}
break;
case DEBOUNCE_STATE_CHECK:
switchValue = readSwitch();
if (switchValue == switchMask)
{
// If minimum debounce period is complete
if ((millis() - lastDebounceTime) > DEBOUNCE_PERIOD_MIN)
{
// Valid switch press
switchStatus = switchMask;
// Wait for button release
debounceState = DEBOUNCE_STATE_RELEASE;
}
}
// A False trigger Dettected
else
{
// Reinitialize button debounce state machine
debounceState = DEBOUNCE_STATE_IDLE;
}
break;
case DEBOUNCE_STATE_RELEASE:
switchValue = readSwitch();
if (switchValue == SWITCH_NONE)
{
// Reinitialize button debounce state machine when no switches are pressed
debounceState = DEBOUNCE_STATE_IDLE;
}
break;
}
// PID computation and appropriate SSR control
if (reflowStatus == REFLOW_STATUS_ON)
{
currentTime = millis();
reflowOvenPID.Compute();
if ((currentTime - windowStartTime) > windowSize)
{
// Time to shift the Relay Window
windowStartTime += windowSize;
}
if (output > (currentTime - windowStartTime)) digitalWrite(ssrPin, HIGH);
else digitalWrite(ssrPin, LOW);
}
// Reflow oven process is off, ensure oven is off
else
{
digitalWrite(ssrPin, LOW);
}
}
switch_t readSwitch(void)
{
// Checking if either the START/STOP or CHANGE PROFILE Pins were selected
if (digitalRead(switchStartStopPin) == LOW) return SWITCH_1;
if (digitalRead(switchLfPbPin) == LOW) return SWITCH_2;
if (!(digitalRead(switchLfPbPin) == LOW) || !(digitalRead(switchLfPbPin) == LOW)) return SWITCH_NONE;
}