So as I mentioned yesterday I roasted some coffee. This time (except for manual control of the fan) the roaster did it all by itself. I had given it a handicap of limiting power to the heater only to 85% of the capacity but it appears to have worked ok. The Arduino roaster controller worked well enough considering the state it is in. Power control from the Arduino worked for manual potentiometer signaling the fan speed and a data array of settings for the heat controlled the roast automatically trying to maintain the temperature.
I’m going to increase the power again to 90%. The room temperature was around 45-50 degrees since I roasted it out in my garage so I think it did pretty well getting to temperature. I’ve also bumped the fan up slightly to a higher maximum.
I will need to get a button controller going soon so that I can force the system from automatic into manual mode so I can quickly shut down heat if necessary without having the laptop connected while letting the fan continue to run. I’ve got a CAD type design of a PCB going that has a button controller but I haven’t ACTUALLY prototyped it out on some RadioShack boards. I do have some etch-able boards here to try a toner transfer to build out some controls. I still need some carbide drill bits though for drilling the through hole parts and the jumper connectors. If I had SMD header pins I think I actually have all the parts I’d need to build a 6 or 7 button analog pin matrix. I may need a couple more resistors though to pull that off. I’m pretty sure I could get at least 4 buttons though.
The power control system had started to get out of control with the heat sinks so I had to beef it up some. Before anyone says it I know the large heat sink is on upside down. I didn’t want to drill the board before I was sure it was going to work so those bottom pins are sticking out the top. I’ll probably run it like this for a little while until I make a permanent board though.
So for those of you keeping track… I went from this:
- First working prototype in Radioshack Project Case
To this:
This is MUCH better for the following reason…heat sinks got out of control and all the wires were getting obnoxious:
Next Steps?
- Increase allowed power to heater
- Make button control pad.
- Tune PID.
- Improve CSV log system.
- Add automation to the Fan control. Use mild PID triggered adjustments to the fan. Coarse heat changes by heater. Minor heat changes (a few degrees) by Fan.
- Add current sensor to judge wattage to the heater.
- Get profiles loading from SD memory using button pad to select them.
- Begin creating circuit to connect my original PIC32 project to the arduino over serial / rx/tx or other communication method.
- Complete 7 inch touch screen (I have a screen designed but it’s not entirely stable yet… the backlight flickers occasionally and the image stutters here and there but it’s there…) I’ll upload a bitmap from the layout tool soon.
- Migrate most functions to PIC32 eventually.
- Build a final PCB.
- Get a case made for it.
- Roast lots of coffee.
- Brew it.
- Drink it.