ReflowberryPi - Takeaway

Future Improvements

Future improvements can be made with this project. Implementation of such things as: better heating insulation, active cooling, network integration, notifications over textmessage or email, better board gripping, analog input heat elements, and much much more. This project has so much more potential implementable extras that there would not be an end to this list.
References

Resource for all things Thermocouples (MAX31855) - https://www.adafruit.com/product/269
Resource for PID - http://www.csimn.com/CSI_pages/PIDforDummies.html
Distribution of work

Hardware Hacking - Brendon, Joe
Software Hacking - Joe, Brendon
Website structure and Formatting - Brendon
Content on website- Joe, Brendon
Code

Download the code
Main Reflow Control Script

#
# REFLOW OVEN MAIN CONTROL SCRIPT
#
# Final Project for ECE 5990
#
# Brendon Jackson - btj28
# Joseph Featherston - jgf82
#

import pygame
import os, sys
import RPi.GPIO as GPIO
import time
import datetime
import collections
from pygame.locals import *


size = (width,height) = (320,240)
black = (0,0,0)
white = (255,255,255)
color_1 = (200,50,0)
color_2 = (50,100,150)
label_color = white
value_color = color_2
positive_color = (0,100,30)
negative_color = color_1
curr_color = (200,10,100)
des_color = (100,100,20)



os.putenv('SDL_VIDEODRIVER', 'fbcon')
os.putenv('SDL_FBDEV', '/dev/fb1')
os.putenv('SDL_MOUSEDRV', 'TSLIB')
os.putenv('SDL_MOUSEDEV', '/dev/input/touchscreen')

pygame.init()

screen = pygame.display.set_mode(size)
screen.fill(black)
pygame.display.flip()

sm_font = pygame.font.Font(None, 20)
md_font = pygame.font.Font(None, 40)
lg_font = pygame.font.Font(None, 80)

graph_surface = pygame.Surface((320,100))
graph = pygame.PixelArray(graph_surface)
graph_surface.lock()
graph[:,:] = black
graph_surface.unlock()

def drawStart():
  start_text  = [
    ('Preheat Temp',(60,20),label_color,sm_font),
    (getValue("preheat_temp"),(60,50),value_color,sm_font),
    ('Preheat Time',(60,80),label_color,sm_font),
    (getValue("preheat_time"),(60,110),value_color,sm_font),
    ('Preheat Rate',(60,140),label_color,sm_font),
    (getValue("preheat_rate"),(60,170),value_color,sm_font),
    ('Peak Temp',(180,20),label_color,sm_font),
    (getValue("peak_temp"),(180,50),value_color,sm_font),
    ('Peak Rate',(180,80),label_color,sm_font),
    (getValue("peak_rate"),(180,110),value_color,sm_font),
    ('Cool Rate',(180,140),label_color,sm_font),
    (getValue("cool_rate"),(180,170),value_color,sm_font),
    ('+',(90,45),positive_color,lg_font),
    ('-',(30,45),negative_color,lg_font),
    ('+',(90,105),positive_color,lg_font),
    ('-',(30,105),negative_color,lg_font),
    ('+',(90,165),positive_color,lg_font),
    ('-',(30,165),negative_color,lg_font),
    ('+',(210,45),positive_color,lg_font),
    ('-',(150,45),negative_color,lg_font),
    ('+',(210,105),positive_color,lg_font),
    ('-',(150,105),negative_color,lg_font),
    ('+',(210,165),positive_color,lg_font),
    ('-',(150,165),negative_color,lg_font),
    ]
  screen.fill(black)
  for text,pos,color,font in start_text:
    text = font.render(text, True, color)
    text_rect = text.get_rect(center=pos)
    screen.blit(text,text_rect)
  text = lg_font.render('GO', True, white)
  text_rect = text.get_rect(center=(275,40))
  screen.fill(positive_color,text_rect)
  screen.blit(text,text_rect)
  pygame.display.flip()


def handleStart():
  drawStart()
  events = pygame.event.get()
  for event in events:
    if event.type == pygame.KEYDOWN:
      if event.key == pygame.K_ESCAPE:
        done()
    if event.type ==  pygame.MOUSEBUTTONDOWN:
      x, y = pygame.mouse.get_pos()
      if isPressed(x,y,275,40,20):
        return False
      elif isPressed(x,y,90,45,20):
        incValue("preheat_temp")
      elif isPressed(x,y,30,45,20):
        decValue("preheat_temp")
      elif isPressed(x,y,90,105,20):
        incValue("preheat_time")
      elif isPressed(x,y,30,105,20):
        decValue("preheat_time")
      elif isPressed(x,y,90,165,20):
        incValue("preheat_rate")
      elif isPressed(x,y,30,165,20):
        decValue("preheat_rate")
      elif isPressed(x,y,210,45,20):
        incValue("peak_temp")
      elif isPressed(x,y,150,45,20):
        decValue("peak_temp")
      elif isPressed(x,y,210,105,20):
        incValue("peak_rate")
      elif isPressed(x,y,150,105,20):
        decValue("peak_rate")
      elif isPressed(x,y,210,165,20):
        incValue("cool_rate")
      elif isPressed(x,y,150,165,20):
        decValue("cool_rate")

  return True


def isPressed(x,y,cen_x,cen_y,size):
  if x<cen_x+size and x>cen_x-size:
    if y<cen_y+size and y>cen_y-size:
      return True
  return False

def drawRun():
  run_text  = [
    ('Current Temp',(70,20),label_color,sm_font),
    (getState("temp"),(70,50),value_color,md_font),
    ('Elapsed Time',(70,80),label_color,sm_font),
    (getState("time"),(70,110),value_color,md_font),
    ('Desired Temp',(250,20),label_color,sm_font),
    (getState("desired_temp"),(250,50),value_color,md_font),
    ('Current Stage',(250,80),label_color,sm_font),
    (getState("state"),(250,110),value_color,md_font),
    ]
  screen.fill(black)
  for text,pos,color,font in run_text:
    text = font.render(text, True, color)
    text_rect = text.get_rect(center=pos)
    screen.blit(text,text_rect)
  text = lg_font.render('STOP', True, white)
  text_rect = text.get_rect(center=(160,180))
  screen.fill(negative_color,text_rect)
  screen.blit(text,text_rect)
  #graph_surface.unlock()
  #screen.blit(graph_surface,(0,140))
  pygame.display.flip()


def updateGraph(currT,desT,t):
  graph_surface.lock()
  graph[t, round(currT/3)] = curr_color
  graph[t, round(desT/3)] = des_color
  graph.surface.unlock()

def done():
  open_Door()
  relay_OFF()
  door.stop()
  quit()



def handleRun():
  drawRun()
  events = pygame.event.get()
  for event in events:
    if event.type == pygame.KEYDOWN:
      if event.key == pygame.K_ESCAPE:
        done()
    if event.type ==  pygame.MOUSEBUTTONDOWN:
      x, y = pygame.mouse.get_pos()
      if isPressed(x,y,160,180,20):
        return False
  return True


#config = {
#  "preheat_temp" : 140,
#  "preheat_time" : 80,
#  "preheat_rate" : 2,
#  "peak_temp" : 235,
#  "peak_rate" :  3,
#  "cool_rate" :  6,
#}
#quick config for demos
config = {
  "preheat_temp" : 60,
  "preheat_time" : 20,
  "preheat_rate" : 2,
  "peak_temp" : 80,
  "peak_rate" :  3,
  "cool_rate" :  6,
}

state = {
  "temp" : 204,
  "desired_temp" : 200,
  "time" : 300,
  "state" : "Boot"
}

def getState(key):
  return str(state[key])

def incValue(key):
  config[key] = config[key]+1;


def decValue(key):
  config[key] = config[key]-1

def getValue(key):
  return str(config[key])

def pushConfig():
  global PREHEAT_TEMP
  global PREHEAT_TIME
  global PREHEAT_RATE
  global PEAK_TEMP
  global PEAK_RATE
  global COOLDOWN_TEMP
  PREHEAT_TEMP = config["preheat_temp"]
  PREHEAT_TIME = config["preheat_time"]
  PREHEAT_RATE = config["preheat_rate"]
  PEAK_TEMP = config["peak_temp"]
  PEAK_RATE = config["peak_rate"]
  COOLDOWN_TEMP = config["cool_rate"]



def updateValues():
  global state
  state["temp"] = temperature_C
  state["desired_temp"] = round(expected_temp)
  state["time"] = round(t-start_time)
  if s == 17: 
    state["state"] = "Preheat"
  elif s == 16: 
    state["state"] = "Startup"
  elif s == 18: 
    state["state"] = "Reflow"
  elif s == 19: 
    state["state"] = "Peak"
  elif s == 20: 
    state["state"] = "Cooldown"
  elif s == 21: 
    state["state"] = "Done"
  else:
    state["state"] = "error!"




# HardWare SPI
#import Adafruit_GPIO.SPI as SPI

import Adafruit_MAX31855.MAX31855 as MAX31855

## CONSTANTS SHOULD NOT CHANGE ##

SERVO_CH = 13
RELAY_CH = 26

DOOR_CL  = 10.0
DOOR_OP  = 5.0

## STATE MACHINE CONSTANTS FOR MENU ##
INIT     = 1 #should display current heating profile
             #and simple buttons to setup the profile
             #and start the process



# RUNNING STATES
WARM    = 16
PREHEAT  = 17
REFLOW   = 18
PEAK     = 19
COOLDOWN = 20
DONE = 21


## CONTROL VARIABLES ##
s = WARM #current state

start_time   = 0
expected_temp= 0
t  = 0


PREHEAT_TEMP = 0 #Celsius
PREHEAT_TIME = 0  #Seconds
PREHEAT_RATE = 0 #C/s

PEAK_TEMP  = 0 # Celsius
PEAK_TIME = 10  #seconds
PEAK_RATE  = 0  #C/s

DONE_TEMP = 30
WARM_TEMP = 50

COOLDOWN_RATE= 8  #C/s

## TEMPERATURE SENSOR INITIALIZATION ##

# SOFTWARE SPI SENSOR
CLK = 25
CS  = 24
D0  = 18


# HARDWARE SPI SENSOR
#SPI_PORT   = 0
#SPI_DEVICE = 0

#sensor = MAX31855.MAX31855(spi =  SPI.SpiDev(SPI_PORT, SPI_DEVICE))
last_temp = 0;
temperature_C = 0;
temperature_F = 0;

## GPIO SETUPS ##

GPIO.setmode(GPIO.BCM)

GPIO.setup(SERVO_CH, GPIO.OUT)
GPIO.setup(RELAY_CH, GPIO.OUT)

## SERVO INITIALIZATION ##
door = GPIO.PWM(SERVO_CH, 50)
door.start(DOOR_CL)



## FUNCTION DEFINITIONS TO ABSTRACT AWAY COMPLEXITY ##
def open_Door():
  door.ChangeDutyCycle(DOOR_OP)

def close_Door():
  door.ChangeDutyCycle(DOOR_CL)

def relay_ON():
  GPIO.output(RELAY_CH, GPIO.HIGH)

def relay_OFF():
  GPIO.output(RELAY_CH, GPIO.LOW)
  
def updateTemperature():
  global temperature_C
  global last_temp
  sensor = MAX31855.MAX31855(CLK, CS, D0)
  last_temp = temperature_C
  temperature_C = sensor.readTempC()
  temperature_F = (temperature_C * 9.0 / 5.0) + 32.0

reflow_time = 0

def updateControl():
  global s
  global t
  global expected_temp
  global start_peak
  global reflow_time
  t = time.time() #microSeconds -> seconds
  if s==WARM:
    expected_temp = (t-start_time)*PREHEAT_RATE
    if expected_temp>WARM_TEMP:
      expected_temp = WARM_TEMP
    if temperature_C > WARM_TEMP-10:
      s=PREHEAT
      reflow_time = t
  elif  s==PREHEAT:
    expected_temp = (t-start_time)*PREHEAT_RATE
    #expected_temp = last_temp+PREHEAT_RATE
    if expected_temp>PREHEAT_TEMP:
      expected_temp = PREHEAT_TEMP
    if t-reflow_time>PREHEAT_TIME:
      s=REFLOW
  elif s==REFLOW:
    expected_temp = (t-PREHEAT_TIME-reflow_time)*PEAK_RATE+PREHEAT_TEMP
    #expected_temp = last_temp + PREHEAT_TEMP
    if expected_temp > PEAK_TEMP:
      expected_temp = PEAK_TEMP
    if last_temp > PEAK_TEMP-10:
      start_peak = t
      s = PEAK
  elif s==PEAK:
    expected_temp = PEAK_TEMP
    if t-start_peak>PEAK_TIME:
      s= COOLDOWN
  elif s==COOLDOWN:
    expected_temp = (t-start_peak-PEAK_TIME)*(-COOLDOWN_RATE)+PEAK_TEMP
    if temperature_C < DONE_TEMP:
      s=DONE
  else:
    expected_temp = 0
  pid()
    # do nothing to output


errors = collections.deque(maxlen=10)

preverror = 0
error = 0
def pid():
  global error 
  preverror  = error
  error      = temperature_C - expected_temp
  errors.append(error)
  p = error
  i = sum(errors)/len(errors)
  d = (errors[len(errors)-1]-errors[0])/len(errors)
  correction = 2*p+4*i+10*d
  if correction < 0:
    close_Door()
    if correction < -10:
      relay_ON()
    else:
      relay_OFF()
  elif correction > 0:
    relay_OFF()
    if correction > 20:
      open_Door()
    else:
      close_Door()







## MAIN LOOP ##


while True:
  while handleStart():
    time.sleep(0.1)
  start_time = time.time()
  pushConfig()
  while handleRun():
    updateTemperature()
    updateControl()
    updateValues()
    time.sleep(1)
open_Door()
relay_OFF()
door.stop()
GPIO.cleanup()