things that work:
- 12v or 24v input to power the Pi, including a switching power converter
- huge capacitor to smooth out any voltage irregularities
- Two MOSFET outputs (my MPMD will get a fan and lighting control; the Prusa will get lights and IDK)
- power monitoring (watts/volts) with INA219 chips, both at the input voltage and at the 5v level (what supplies the Pi, perhaps it'll help detect undervoltage)
- temperature/humidity monitoring, with both LM75 and ENS210 chips
- found or wrote Python for all of these.
failure is always an option. other parts:
- testbed for four WS2812 LEDs. I desoldered these, wasn't happy.
- LM75 temperature sensor. Will remove from design, the ENS210 sensor has humidity, is much more accurate, and takes a smaller footprint
No surprise, I'm already designing the next version:
- I'm going to remove the WS2812s and add two 8-LED bar graphs. They will come in handy for printer progress, voltage/power usage, CPU, who knows.
- will add three buttons: safe poweroff, poweron, and 'BRB' to abort a print.
- will probably add some status LEDs too.
Here's the software output of the monitoring chips:
Bus Voltage: 12.272 V Supply voltage: 12.270 V Bus Current: 118.598 mA Power: 1277.439 mW Shunt voltage: 2.230 mV Bus Voltage: 4.976 V Supply voltage: 4.981 V Bus Current: 225.457 mA Power: 972.561 mW Shunt voltage: 4.320 mV ens210 temp: 24.90 ens210 hum: 33.35 lm75 temp: 26