User Manual

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18 OpenTracker 2.4 User Manual (1.4.0)
Customizable EXT PIN
Using EXT PIN
The EXT Pin on the main connector has no function. It is routed to the internal I/O connector.
This may be used for anything the user desires. For example with a 1-wire communication or additional
analog lines. Simply connect the IO_TO_EXT Pin on the Internal I/O pin header to your custom setup.
Please note:
When connecting any Internal I/O Pin to the IO_TO_EXT that those have 3.3V levels and are
directly connected to the MCU. We recommend to protect the pin against overvoltage.
Example usage - One Wire
In this example four DS1820 Temperature sensors are driven in 1-wire parasite power mode. Including basic
I/O protection with a 3.6V Zener diode (D1).