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8-channel Bi-directional Logic Level Converter - TXB0108

by tfbkny on Sat Mar 09, 2013 2:18 am

Question: Is this accessory needed to be able to have the Raspberry pi's 3.3v GPIO out signals to pilot an 8 channel 5v opto-isolated relay board?

So far I see the 3.3v with a voltmeter, the signal appears fine and stable, when triggering the out on the GPIO pin using BerryIO... so the pin outputs the voltage just fine, although the relay board doesn't seem to work even when everything is powered on and connected as it should. Could anyone lend a hand? Do I need the 8-channel Bi-directional Logic Level Converter - TXB0108 to get a usable signal that could drive the relay board?

Thanks in advance for any and all help.

Cheers! :)
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Re: 8-channel Bi-directional Logic Level Converter - TXB0108

by adafruit_support_bill on Sat Mar 09, 2013 7:10 am

Not familiar with the relay board you mention. But most 5v logic does respond to 3.3v signals. It is possible that the logic "HIGH" threshold for your board is somewhat higher than 3.3v, in which case a level converter would help.

Where the level shifter is essential is when there are 5v signals coming back into the 3.3v Pi. The Pi is not 5v tolerant and these signals would cause damage to the GPIO pins.
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