Actually, these are reused from my first CNC project, which lies behind a pile of junk in the garage. With a locking washer, I was able to mount these to the bot.
OK, maybe not as dramatic, but it was just as vital.
With my final project deadline extended a week, I took a couple days of downtime to catch up on sleep. The all-nighters were adding up. Now I’m back and making some minor changes and a few fixes. Hopefully the thing will drive in reverse without catching on fire. If you don’t hear from me, send help.
Firmware for the not has been fleshed out and I’m looking forward to getting it coded. The loop is simple, checking the status of each input and setting a flag. That flag is passed to the three output functions, which run after the input stage. One exception is the turnaround() function, which is called by an interrupt on the whisker pin. Some output functions call themselves to complete a series of drive commands, for instance. This keeps things simple.
More to come.
Over-voltage protection for each rail of my project’s power supply in the form of a thyristor (silicon controlled rectifier or SCR) based crowbar circuit. The Zener breakdown voltage determines the cut off and trips the gate of the SCR, causing a short condition. The short is then handled by a fuse, protecting sensitive devices. A threshold of about 1V for the Zener diodes (4.3V for the 3.3V rail & 6.2V for the 5V rail) was selected to allow for overhead in case of transient spikes.