After some work mounting circuit boards and creating wiring harnesses to connect everything together I wired up a 5 volt power supply to run a case exhaust fan and fired up the coffee roaster controller for a quick test. The program was not optimized for a new bag of beans I was roasting so it didn’t hit good temperatures at the right times in my opinion but it worked.
At this time I have disconnected all of the FreshRoast SR500 control electronics and replaced everything from the wall to the heater and fan connections with my own boards. I’m using an Arduino Mega 2560 with an Ethernet Board (it gets NTP time to set time and date on the logs by itself and I hope to add some ethernet based communication to collect the log data without popping the microSD memory out). The Arduino is mounted in a Crib for Arduino and connected via wiring harness to a DB25 cable that connects to the back of a Ponoko laser cut case prototype.
I screwed up a few calculations on the Ponoko case but the idea will work and the glues I need to use will allow me to connect all the sides together and mount everything securely when I send it in for “round 2”. Inside the case I’ve got several Sparkfun boards as well as some other manufacturer breakout boards mounted to a “connector board” that links them all together and to the DB25. There is also a 25VAC transformer and my original RadioShack parts power control board. I need to figure out what I need to do to have a suitable AC handling PCB though since most of the easily produced boards would not have thick enough copper to handle the 1500 Watts of AC power to my understanding.
I still need to do a bit more work to get anywhere I’m comfortable with it. I’m intending to get most of the following done before I consider it “more than a rough prototype”:
- Enable toggle for manual vs automatic controls
- Replace PID code with a better system that I think I understand better to tune it properly
- Create menu to setup automatic profiles
- Allow ability to convert a previous manual run to an automatic profile
- Fix wiring on a few sensors that didn’t register properly
- Create a second board to replace the current board that includes many of the sensors directly on board
- Move the 7 volt to 5 volt power supply inside the case to run the fan and start powering other sensors
- Update the button matrix and change the way I drive the LEDs on it to minimize pin use.
Ultimately, however, it worked well enough. Once I get it through these items and kick out a new case I’ll start trying to find ways to document more of how this went together to help others figure out how to come up with something similar. After that I’ll begin working more on the PIC32 side trying to convert from Arduino to PIC32 and get my 7 inch touch screen mounted to a front panel and add more functions.