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Topic: Using an analog multiplexer with the arduino due (Read 101 times) previous topic - next topic

BenS1000

I got this analog multiplexer: http://www.mouser.com/ds/2/405/cd74hc4067-441121.pdf
and I want to make sure that it will work with the arduino due.

When I tested it with my arduino uno it didn't work because the wide range of voltages for high and low signals didn't match the narrower range of voltages that the multiplexer was expecting.

Will the arduino due have the same problem? I know it uses different logic levels because it uses 3.3V, but I looked through the datasheet of the Atmel SAM3X8E in the due and I couldn't find out what the range of voltages for high and low signals are.

MarkT

You should look a little harder, the Due is 3.3V only, this is clearly indicated everywhere I've seen.
You can only feed values from 0.0 to 3.3V into a Due pin if you want it to survive.

The HC family will run at 3.3V, the HCT family will not.

If you are thinking of using the DAC outputs of the Due note that they only range from Vcc/6 to
5/6*Vcc.
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BenS1000

Sorry if I wasn't clear, I'm talking about the logic levels that the arduino due outputs as high and low to control which pin on the multiplexer is selected, not the voltages that the due can accept as input (I knew that that can't be higher than 3.3V)

And also, I have the HC version, not the HCT, so that shouldn't be an issue.

MorganS

Go to page 3 of that datasheet. Look at the first item in the big table: High level input voltage. Notice how it only gives a minimum and no maximum? This is the minimum voltage required to register as a logical HIGH. It doesn't give a value for 3.3v supply but by looking at the others, you could estimate that the minimum high voltage is 0.7 times the supply voltage, or 2.31V for a 3.3V supply.

Now go to the Due datasheet and look for its minimum voltage when outputting a HIGH. I haven't looked myself but I think you will find it's more than 2.31V, even when the output is loaded to its maximum rated current output.

It should work with the Uno. There must be some other problem with your test.
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