Espresso machine, control vibe pump power output
This software runs on an Arduino to control the output of a vibe pump to allow changing the pump power for pressure profiling. I used an Arduino Nano just to do this, makes it easier with dedicated processor.
Description of hardware is here https://sites.google.com/view/coffee4randy/projects/pump-control
Uses an optocoupler for zero crossing detection (ZCT) of AC power, and then generates an interrupt when it detects Uses pin D2 for interrupt input
All relevant SW runs in the interrupt controller. Normally you should keep interrupt handling short, reason to use a dedicated processor.
When ZCT interrupt comes in, pump power is off. Interrupt reads pump power level setting, power level (0-128) 0 = full ON, 128 = OFF Multiplies power x 65 (for 60 Hz). Note that 126 * 65 = 8320 microsecs. About 1/2 of 60 Hz waveform.
Leaves pump power off for offtime = power x 65 microsecs.
Then turns on pump power for ontime = (8330 - dimtime + DELAY_AFTER_STOP).
DELAY_AFTER_STOP = 8330/2, or 1/4 waveform. It is there to stop inductive kickback from the pump when you turn it off.
Then turn pump off, and exits interrupt.
Pump power is read from analog input A0.
The main program reads A0, then scales from 0-1023 to 128-0 for an actual pot that is connected to +5V, A0 and ground.
It scales backwards so when you turn the pot clockwise the pump power goes up.
Can also use ESP32 analog output, to let ESP32 control pump power for automated pressure profiling. Change scale to be from 0-675 to 128-0 for a 3.3V output to A0