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Visitor
Visitor
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Registered: ‎11-26-2019

Using PMOD Header J58 for ZC706

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Hi:

I'm currently using ZC706 J58 header as a normal GPIO for some input signal trig and output port. However, I have a problem which is the port which is defined as input (pull-down in constrain file) always shows high voltage level (3.3V). I'm wondering whether this J58 can be defined as usual GPIO port?

 

Thanks


Kevin

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Advisor
Advisor
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Registered: ‎04-26-2015

It can be used as GPIO, but the PMOD is not connected directly to the FPGA pins. It goes through a TXS0108E level shifter (U40), which has internal pull-up resistors - either 40K or 4K depending on what it's doing. This will be fighting against the Zynq's pull-down.

 

Have you tried just connecting the PMOD pins to ground? Does that give you a "0" on the pin, or is it still reading "1"?

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Advisor
Advisor
189 Views
Registered: ‎04-26-2015

It can be used as GPIO, but the PMOD is not connected directly to the FPGA pins. It goes through a TXS0108E level shifter (U40), which has internal pull-up resistors - either 40K or 4K depending on what it's doing. This will be fighting against the Zynq's pull-down.

 

Have you tried just connecting the PMOD pins to ground? Does that give you a "0" on the pin, or is it still reading "1"?

View solution in original post

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Visitor
Visitor
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Registered: ‎11-26-2019

We tried to pull up the J58 header and it looks good now. Thanks for your suggestion.

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