40-Channel MRBus Digital I/O Node



The MRB-XIO is a 40-channel digital I/O expander with an I2C interface, based on the NXP PCA9698.  The board includes a 6P6C I2C Connector, the PCA9698, a 5V @ 1.5A switching regulator, an ATmega328 and MRBus interface, and all I/Os pinned out to either terminal blocks or RJ11 jacks (in blocks of 4 I/O lines, including +5VDC and Ground on the other two pins).

Unlike many other I2C I/O solutions on the market, the PCA9698 doesn't impose significant restrictions on the total current it can source or sink.  Many parts rate +/- >20mA per I/O pin, but are severely limited by the total current the part can handle.  The PCA9698 is rated for sourcing 500mA and sinking a whopping 1100mA, allowing for significant current draw on each I/O line.  We've also included a 1.5A switching regulator on board so that you can achieve those current outputs without wasting significant power or hitting thermal limits.

The reference firmware allows you to configure the 40 onboard I/O lines in any combination of inputs and outputs, send status messages with each I/O's state, and allows you to set the outputs with a command.  For additional functionality, the user will need to be familiar with AVR C development.

To add even more I/O lines via the I2C connection, or for a version without the integrated microcontroller and MRBus interface, check out the I2C-XIO instead.


6.0"(L) x 1.7"(W)


The complete gEDA design files are available on GitHub.


6P6C I2C Connector Standard

  • $60.00

Available Options

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