40-Channel MRBus Digital I/O Node
MRB-XIO
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.
Specifications
6.0"(L) x 1.7"(W)
Documents
The complete gEDA design files are available on GitHub.
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40-Channel I2C Digital I/O Expander
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News & Application Notes
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As alumni of the Iowa State University Solar Car Team, Team PrISUm, we recognized that many of Iowa Scaled Engineering’s products could be used by teams competing in solar racing competitions. In fact, MRBus had its origins in the Sunrayce ’99 car, PrISUm Phoenix.
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