Hendi Induction cooker model 3500 M Setup
If any of 0V, 5V, ON/OFF, power or the RPi gets in contact with the Hendi Chassis the cooker and RPi will be damaged beond repair.
In the original setup a potentiometer with a built in switch is used. The switch switches the power on/off and the potentiometer controls the power. With 5V on the power pin 500W is set and with 0.8V 3500W) is set. Backside/terminals of the potentiometer:
The Buffalo CE208 seems to have a near identical internal construction (the potentiometer board is identical.)
To interface a Hendi induction cooker it's necessary to isolate the cooker (that is the chassis and all signal wires) from the RPi. For example with opto couplers. This is an example of a working schematic (tested with FOD817B opto couplers):
The addition of two relays and some kind of control would be an easy extension to the controls described here and would preserve the functionality of the existing potentiometer & switch. The adapter board in this repository provides for switching between external control and the original potentiometer though it does require an external I2C connection.
#CraftBeerPi setup Right now there are two Hendi modules "hendipid.py" and "hendipowerctrl.py". The first one is used when controlling the temperature of the wort, the second one is used when boiling. When using the power control module the output power is controlled by setting the "target temperature" for example a "target temperature" of 45 will correspond to about 2000W.
Example, a system with one kettle located on the Hendi cooker a 1-wire temperature sensor:
Configure "Heater" to GPIO22
Configure a "Thermometer" with name Thermometer
Add a kettle in "Kettle Configuration" name it TempControl, select Thermometer and Heater. Select hendipid under control logic and configure if necessary. Set values in additional data.
Add one more kettle in "Kettle configuration" (yea you need two even if you only have one). Name it PowerControl, select Thermometer and Heater. Select hendipowerctrl under control logic and configure if necessary. Set values in additional data.
How to use
How to tune the PID controller