As alluded to earlier in the blog I am intending on building a roaster controller system. I’m probably a bit of an over-achiever in terms of my projects because every time I create something on the internet for one of my websites, as part of a building project in the yard, or whatever else I’m creating I always over-analyze it. In my career one of the areas I’ve been responsible for was “Disaster Recovery” planning for computer systems. In other words my job was to over-analyze all the things that could go wrong and figure out a plan to deal with them. At the same time I also have to plan all the ways for it to go right and have a plan so anyone can do it even without strong computer skills.
Focusing on a roast controller as mentioned I’ve already purchased some testing equipment for measuring temperature using a K type thermocouple. I am now finalizing the equipment that I’m going to use to build this and test it. I’ve focused on using the PIC32 microprocessor due to its abilities to work easily with Ethernet, LCDs, and having many input/output circuits. In addition it seems to be a robust platform for RTOS systems allowing a lot to be going on all at the same time.
To ease development I am choosing to embrace the development tools provided by the manufacturer. This of course adds to the startup cost of the system but allows me to “try new things” in the future too using the development platform. Once I finalize the project I would then order the individual components and manufacture my own circuit boards. To start off I expect to need the following.
The Starting Parts
- DM320003-2 – PIC32 USB Starter Kit II – $55.00
- Main processor (MCU) test board.
- Contains PIC32MX795F512L processor.
- 80 MHz with 512K Flash, 128K RAM. (this is actually a lot for a simple coffee roaster but is necessary for drawing graphical LCD, developing complex roasting profiles, and loading Ethernet overhead.)
- Allows USB, Ethernet, LCD, I2C and SPI communications.
- DM320002 – PIC32 I/O Expansion Board – $72.00
- Connector to access pins and interface auxiliary boards.
- AC164132 – Fast 100Mbps Ethernet PICtail Plus Daughter Board –$49.99
- Physical wired ethernet board for interface to DM320002.
- AC164126 – Prototype PICtail Plus Daughter Board – $20.00
- Prototype boards to solder additional parts and extensions such as temperature probe chips, time devices, relays, etc.
- AC164127-3 – Graphics PICtail Plus Daughter Board with 3.2 Display Kit – $154.99
- SSD1926 Graphics chip (kind of like a video card)
- 3.2 QVGA (240X320) TFT LCD with 18-bit parallel RGB interface
- Touch Screen
The Later Parts
The above parts allow me to start testing User Interface functionality without worrying too much about the circuit boards except for the occasional prototype board communicating with a sensor or two. I’m doing that to determine the final touch screen configuration and “what is possible” on the screen real estate to determine if I want to pursue additional sensors and features. It will also allow me to begin testing response time of various sensors on the prototype boards. Some parts I expect to need:
- MAX6676 Thermocouple Amplifier
- DS3232 Real Time Clock
- Lots of resistors
- Lots of capcitors
- Various Transistors
- Lots of diodes
- Photosensitive PCBs
- PCB etch Chemicals and developer
- SMD soldering and hot air rework station
- Infrared circuit board pre-heater station
- Small Drill Press w/ bits for drilling PCBs
- Oscilloscope for dimmer testing
- Several relays and/or some dimmer circuits that need to be designed still.
- Probably a video camera at some point to demonstrate progress/results.