I started a project that will allow me to use a raspi with a relay to measure and control the temperature of a Maple Evaporator using a fan to force air via 12v fan to increase the combustion of a wood-burning stove, thus increasing the temperature and allowing the wood boiler to stay at a specified temperature.
So I am trying to create an HTML web-form that will accept a number (any whole number 0-1000) and insert it into a PHP web file that will then insert it into an exec() function within the PHP file. So far I have been successful on creating an Html web form and using variable name ($HOLD_TEMPERATURE) to be inserted into the exec() function, but the python script that the exec() is running will not accept the variable name, only real number values such as 1, or 66, or 450, or 1000, and so on... If I open an Xterm session and insert the real number into the script, the program runs without any issues. Also, if I substitute a real value into the PHP file the script will also run without issues. I added some debugging values in the exec() function to help explain what is happening, as shown below.
So is there an option for me to enter a real number in the web form and it automatically propagates into the python script without a $variable needed?
Below is the Html code, PHP, and python script. Thanks!
<!DOCTYPE html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Temperature of Maple Evaporator </title>
</head>
<link href="stylesheets/common.css" type="text/css" rel="stylesheet">
<body>
<h1>Temperature of Flue</h1>
<form method="post" action="web-hold-temperature.php">
Temperature: <br />
<input type="number" name="HOLD_TEMPERATURE" size="35" />
<br />
<input type="submit" value="Submit Temperature (F)" />
<br />
</form>
</body>
</html><?php
$HOLD_TEMPERATURE = $_POST['HOLD_TEMPERATURE'];
if(empty($HOLD_TEMPERATURE )) {
echo "<h2>You must fill in temperature field</h2>\n" ;
die ("Click Back to start again.");
}
echo "<h2>You Entered the following information:</h2>";
echo "<b>Temperature:</b><br><br>";
echo $HOLD_TEMPERATURE;
?>
<?php
exec('bash -c "sudo ./tempctl/temperature_hold \$HOLD_TEMPERATURE 2>&1"', $output);
print_r($output);
?>
Here is the python script that is executed within the PHP file.
#!/usr/bin/python
#robogaia.com
#temperature controller
# the temperatures are in Fahrenheit
# temperature_hysteresis sets how low the temperature
#goes until the heater starts
import SMBus
import time
import datetime
from subprocess import call
import sys
bus = smbus.SMBus(1)
#I2C address
address = 0x4d
#this will tell how low will go until the heater starts again below the set point
temperature_hysteresis = 5
isHeating = True
filterArray = [0 , 0, 0 , 0 , 0, 0, 0, 0] #holds the filter values
def filter(input_value):
filterArray.append(input_value);
filterArray.pop(0);
result = (filterArray[0] + filterArray[1]+ filterArray[2]+ filterArray[3]+ filterArray[4]+ filter
Array[5]+ filterArray[6]+ filterArray[7])/8 ;
stringFilterArray = [str(a) for a in filterArray];
#print(", ".join(stringFilterArray));
return result;
def get_fahrenheit_val():
data = bus.read_i2c_block_data(address, 1,2)
val = (data[0] << 8) + data[1]
return val/5.00*9.00/5.00+32.00
def get_celsius_val():
data = bus.read_i2c_block_data(address, 1,2)
val = (data[0] << 8) + data[1]
return val/5.00
def set_cold():
print "cooling"
call(["temp_relay_on", "cold"])
call(["temp_relay_off", "hot"])
def set_hot():
print "heating"
call(["temp_relay_on", "hot"])
call(["temp_relay_off", "cold"])
def set_close():
print "hold"
call(["temp_relay_off", "cold"])
call(["temp_relay_off", "hot"])
def main(argv):
if len (sys.argv) < 2 :
print "Usage: temperature_hold [temperature] "
sys.exit (1)
set_point=sys.argv[1]
try:
set_point=float(sys.argv[1])
except ValueError:
print "the argument is not a number"
sys.exit (1)
print "set point =" , set_point
print "temperature hysteresis =" , temperature_hysteresis
def main(argv):
if len (sys.argv) < 2 :
print "Usage: temperature_hold [temperature] "
sys.exit (1)
set_point=sys.argv[1]
try:
set_point=float(sys.argv[1])
except ValueError:
print "the argument is not a number"
sys.exit (1)
print "set point =" , set_point
print "temperature hysteresis =" , temperature_hysteresis
#main loop
while 1 == 1:
#get the temperature form sensor
temperature_raw =get_fahrenheit_val()
temperature = filter(temperature_raw);
#uncomment this for celsius
#temperature = get_celsius_val()
print temperature
#verify if we need to cool or to heat
if temperature > set_point :
set_cold()
isHeating = False
elif temperature <= (set_point- temperature_hysteresis):
set_hot()
isHeating = True
elif isHeating == True and temperature <= set_point:
set_hot()
else:
print "hold"
time.sleep(5.0)
if __name__ == "__main__":
main(sys.argv[1:])
[Here is the resultant log message from the exec() function is run. ][1]
