Thermal Chamber

therm.py

import usbtmc
import serial
import time
import sys
import math

temperature = 0.0

def printparams():
	# Get the elapsed time
	elapsed = time.time() - clock_start
	elapsed = math.floor(elapsed)

	# Get the frequency
	sa.write(":CALCulate:MARKer1:PEAK:SET:CF")
	time.sleep(2)
	freq = sa.ask(":CALCulate:MARKer:FCOunt:X?")

	# Get the temperature
	ser.write('t')
	t = float(ser.readline().strip())

	# Print it out in comma delimeted format
	print '{},{},{}'.format(elapsed, t, freq)
	
	return t

# Arduino serial dev paramaters
DEVICE = '/dev/ttyUSB0'
BAUD = 9600

# Open the DG1022 arb and config for reading frequency
sa = usbtmc.Instrument(0x1ab1, 0x0960)

# Preset
sa.write(":SYST:PRES")
time.sleep(1)

# Set the ref to +20 dBm
sa.write(":DISP:WIN:TRAC:Y:SCAL:RLEV 20")
time.sleep(1)

# Peak Search
#sa.write(":CALCulate:MARKer1:STATe ON")
sa.write(":CALCulate:MARKer1:PEAK:SET:CF")
time.sleep(1)
sa.write(":FREQuency:SPAN 1000000")
time.sleep(1)
sa.write(":CALCulate:MARKer1:PEAK:SET:CF")
time.sleep(1)
sa.write(":FREQuency:SPAN 10000")
time.sleep(1)
sa.write(":CALCulate:MARKer1:PEAK:SET:CF")
time.sleep(1)
sa.write(":FREQuency:SPAN 1000")
time.sleep(1)
sa.write(":CALCulate:MARKer1:PEAK:SET:CF")

# Set the marker for frequency counting
sa.write(":CALCulate:MARKer:FCOunt:STATe ON")
sa.write(":CALCulate:MARKer:FCOunt:RESolution 1")
time.sleep(3)

# Open serial port
try:
	ser = serial.Serial(port=DEVICE, baudrate=BAUD, timeout=2)
except:
	print 'Cannot open serial port'
	sys.exit(0)
	
ser.write('t')
ser.readline()

# Start the clock
clock_start = time.time()

# Take the first reading
temperature = printparams()

# Turn on the light and fan
ser.write('L')
ser.write('F')

# Main processing loop
while temperature < 60.0:
	time.sleep(30)
	temperature = printparams()
	
# Turn off light
ser.write('l')

# Main processing loop
while temperature > 35:
	time.sleep(30)
	temperature = printparams()
	
# Turn off fan
ser.write('f')




	

thermalchamber.ino

#include <Wire.h>
#include <OneWire.h>

const int fan_relay = 7;
const int light_relay = 6;

OneWire  ds(10);  // on pin 10

void setup(void) {
  Serial.begin(9600);
  ds.reset();
  
  pinMode(fan_relay, OUTPUT);
  pinMode(light_relay, OUTPUT);
}

unsigned int readBytes(int count)
{
    unsigned int val = 0;
    for (int i = 0; i < count; i++)
    {
        val |= (unsigned int)(ds.read() << i * 8);
    }
    return val;
}

float readTemp(void)
{
  byte temp_read = 0;
  unsigned int count_remain = 0;
  unsigned int count_per_c = 0;
  byte configuration_register = 0;

  ds.reset();
  ds.write(0xEE); //Start Converting the temperatures  
  
  do {
        delay(1);
        configuration_register = 0;
        ds.reset();
        ds.write(0xAC);

        // Read the configuration Register from the DS1821
        configuration_register = readBytes(1);
    } while ((configuration_register & (1 << 7)) == 0); // If Bit #8 is 1 then we are finished converting the temp

  
    // Get Temp
    ds.reset();
    ds.write(0xAA);
    temp_read = readBytes(1); ;

    // Get Count Remaining
    ds.reset();
    ds.write(0xA0);
    count_remain = readBytes(2);

    // Load The Counter to populate the slope accumulator
    ds.reset();
    ds.write(0x41);

    // Read Count Per Deg
    ds.reset();
    ds.write(0xA0);
    count_per_c = readBytes(2);

    // If we are reading above the 200 mark then we are below 0 and need to compensate the calculation
    if (temp_read >= 200) temp_read -= 256;

    float highResTemp = (float)temp_read - .5 + (((float)count_per_c - (float)count_remain) / (float)count_per_c);

    // highResTemp = (float)((1.80 * highResTemp) + 32.00);
    Serial.println(highResTemp);
}

void loop(void)
{
  unsigned int rx_byte;
  
  if (Serial.available() > 0)
  {
    rx_byte = Serial.read();
    
    switch(rx_byte)
    {
      case 'L':
        digitalWrite(light_relay, HIGH);
        break;
      case 'l':
        digitalWrite(light_relay, LOW);
        break;
      case 'F':
        digitalWrite(fan_relay, HIGH);
        break;
      case 'f':
        digitalWrite(fan_relay, LOW);
        break;
      case 'T':
      case 't':
        readTemp();
        break;
      default:
        break;
    }
  }
}