HIZ output/releasing an output

NETMF & Gadgeteer
1

Hi guys,

I have parallel port lines that can either be Low or High, where high is pulled up to 3v. Setting a pin low is easy, but how can I release a pin, and let the pull up get it up to 3v, without actually setting the pin high (which would cause problems as a usbizi high is 3v3).

How do I go about that?

2

There is TristatePort in NETMF for that

3

So if a tristate pin is set to “Input” will it act as a HIZ pin, and let the pin float up to 3v?

4

Yes, as explained in the free ebook :slight_smile:

5

I’ve read that chapter of the ebook before asking - it doesn’t actually mention the impendence of the pin, nor this application, so I wanted to confirm.

6

Is this an issue with 3V versus 3.3V, where 3.3V is too high?

How about a diode?

7

Well I might aswell use HIZ, since the pin is pulled up internally to 3v on receiving chip.