I have tried to follow the instructions here: http://forum.brewpi.com/discussion/448/temperature-probe-calibration
I’ve installed ‘screen’ on the Raspberry Pi with
sudo apt-get install screen
Then tried to stop the script running using the Web Interface (which seemed unreliable. Is there a better way to stop it?).
I then open communication to the Spark Photon using:
screen /dev/ttyACM0 57600
(you exit screen with ctrl-a, then k)
which gives me an initially blank screen. I followed the advice to first prepare the commands ( also found here http://wiki.brewpi.com/index.php/Temperature_Sensor_Calibration ) in a text editor and to copy them, then paste the whole command into the command line.
When I paste in
h{v:1}
I get output
h:[{“i”:3,“t”:1,“c”:1,“b”:0,“f”:5,“h”:2,“d”:0,“p”:0,“v”:
1.813,“a”:“288AF6C007000042”,“j”:
0.000},{“i”:-1,“t”:0,“c”:1,“b”:0,“f”:0,“h”:1,“d”:0,“p”:17,“x”:0},{“i”:-1,“t”:0,“c”:1,“b”:0,“f”:0,“h”:1,“d”:0,“p”:16,“x”:0},{“i”:-1,“t”:0,“c”:1,“b”:0,“f”:0,“h”:1,“d”:0,“p”:11,“x”:0},{“i”:-1,“t”:0,“c”:1,“b”:0,“f”:0,“h”:1,“d”:0,“p”:10,“x”:0}]
Which looks like the temp sensor is at index 3 (which matches the device slot I assigned it). I’m assuming the other “i”:-1’s are the outputs?
So on the assumption that the sensor is at index 3 I copy pasted this offset command:
U{i:3,j:-0.438}
because I wanted to reduce the reading by 0.438C (calibrating using ice water slush after letting the sensor sit for some time).
I then get output
D:{“logType”:“E”,“logID”:12,“V”:[3]}
D:{“logType”:“E”,“logID”:13,“V”:[3]}
U:{“i”:3,“t”:1,“c”:1,“b”:0,“f”:5,“h”:2,“d”:0,“p”:0,“a”:“288AF6C007000042”,“j”:
0.000}
Which looks like it’s trying to tell me something went wrong? And the “j” value is not any different to what it was before. Rerunning the h{v:1} command shows basically the same initial output (the “v” or temperature reading was slightly different, but not by 0.438 degrees), also with an unchanged “j” value.
Am I doing something wrong? Are those instructions not valid for the current firmware of the Spark Photon (0.4.3)? How do I show that the offsets are having some effect, or are being set at all?