Fabricating custom displays for a commercial coffee roaster


Roasting the perfect coffee bean is an art form. But even the most talented of roasters can use a little feedback on what’s going on with their equipment. [Ludzinc] recently helped out a friend of his by building this set of 7-segment displays to show what’s happening with this coffee roaster.

The yellow modules hiding underneath the display panel are responsible for setting the speed of the hot air blower and the rate at which the drum turns. They’re adjustable using some trimpots, but it sounds like the stock machine doesn’t give any type of speed feedback other than direct observation.

The solution was to patch into those speed controllers using the ADC of a PIC chip. They each output 0-10V, which [Ludzinc] measures via a voltage divider. After the speed is quantified the microcontroller outputs to one of the displays. Since there’s a different chip for each readout, the firmware can be custom tuned to suit the operator’s needs.

Keep this in mind if you’re still planning to build that coffee roaster out of a washing machine.

Computer controlled coffee roasting

I knew about this when it came out, but it never made it’s way to Hack-A-Day. We’ve mentioned a computer controlled roaster before, but this one is far and away the best I’ve seen. [Jeffrey Pawlan] has been selling individual units to the coffee industry (and extreme coffee geeks) – with good reason. He modified an already sweet Hottop coffee roaster (~$500 US) to be completely computer controlled. He wrote a complete software interface that accounts for room temperature to create complex, repeatable roast profiles. More than anyone, I’ve lamented the lack of details on the system. It’s a safe bet that he’s using more than a few thermocouples with a multi-line A/D converter. Anyone feel like writing some open source coffee roaster software? Modifying my current setup wouldn’t be that difficult.