I’m steadily building the firmware for this thing. Something that sounds simple is turning out to be a little more complex than I thought, still, that’s pretty normal in the software world. My program is around 600 lines and I’ve still got a lot of stuff left to do.

Another problem I’ve come across is the Potentiometer voltage ramp arrangement has turned out to be not very accurate, the reading varies wildly depending on voltage, temperature, current and just about any other variable you can think of. After wasting a lot of time with it, I’ve decided it’s just not a suitable method for setting the speed.

So instead, I’ve got myself a rotary encoder. This looks like a potentiometer but it’s actually a binary counter which increments as you turn it. It has detents so it won’t drift once you turn it to a specific position and is generally much more suitable for this role.

Of course, I now have to modify the software to read it.