Help with Labjack U12/Labview project
Posted 15 August 2012 - 09:48 AM
Posted 15 August 2012 - 09:56 AM
For digital expansion or multiplexing, we and customers have used a port expander IC. We have used the MCP23S17 before:
This would let you use 2-4 IO lines to control 16 LEDs.
Posted 16 August 2012 - 07:01 AM
Posted 16 August 2012 - 09:42 AM
Posted 21 August 2012 - 08:59 AM
Posted 21 August 2012 - 09:11 AM
I had never heard of Charlieplexing, but when I looked it up it seems to turn on one load at a time. See the "Operation Table" here:
I understand that I could use a Port Expander. Is there a reason that Charlieplexing wouldn't work though?
The U12/U3/U6/UE9 all have tristate digital I/O. The 3 states are output-high, output-low, and input. So, set the line to input to get your 3rd state.
Also, I see that the U12 allows tri state pins like I need, however, I do not know how to set this third state. In other words, boolean true/false correspond to on/off. What input is necessary for the 3rd, high impedance state?
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