[Twiz O'Meter] Expansion port: technical information.

If you would like to customize your ToM more you can easily do this using the expansion port, which is the middle cable coming from the Blackbox.
For other info about this port you can refer to the ToM user manual.


Here I'd like to add other technical information.

The VCC wire provides 5V DC, with max 250/300 mAh. If you exceed this current the fuse inside the OBD connector will burn.
Pin 1 & 2 can be used, indipendently, as input or output, active low or active high, according to the settings of the web server "Expansion board" page.

Pin 1 & 2 are connected directly to the ESP32.
For this reason the voltage in these pins is limited to 3.3v.
So, if you want to use them as input, you have to use a resistor divider.
In the picture below you see the resitors values you can use according to the input voltage.
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When you use Pin 1 or 2 as output, to control for example a relais, it's preferable to set them as active high.
In the picture below you see how you can connect a relais, throght a transitor, on these pin.
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