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Observer
Observer
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Registered: ‎05-17-2018

Using PMOD pins as input

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Hello -

I am using a VCU118 and I would like to use the PMOD pins as an input. Do these PMOD pins already have an ADC and DAC attached to them so that I can just freely use any of the PMOD pins as an input?  

i.e if I send a voltage high signal (1.2V) to PMOD1_0, will i see it as a logic 1 on the fpga board? 

 

Thanks

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Observer
Observer
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Registered: ‎05-17-2018

Re: Using PMOD pins as input

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Had to use a pull up resistor with the 3.3V pin that they provide to pull up the 1.2V/1.8V signal coming out of the PMOD pins to 3.3V.

 

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Adventurer
Adventurer
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Registered: ‎09-13-2018

Re: Using PMOD pins as input

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You need to check in documentation, but PMODS pins should be connected to 3.3V IO banks.
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Observer
Observer
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Registered: ‎05-17-2018

Re: Using PMOD pins as input

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That's what i've been seeing on the forums but it doesn't make sense because in the constraints, it is set by default to LVCMOS12 and not LVCMOS33.

 

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Registered: ‎06-21-2017

Re: Using PMOD pins as input

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Look at pages 91 and 92 of the user guide.  There are level shifters on the PMOD connections.  The connector side is at 3.3V, FPGA pins connected to J52 are powered by VADJ_1V8_FPGA and the FPGA pins connected to J53 are powered by VCC1V2_FPGA.  The PMOD connectors expect 3.3V and the level shifters convert to 1.8V CMOS or 1.2V CMOS. 

Can you explain your previous post about DACs and ADCs connected to the PMODs?

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Observer
Observer
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Registered: ‎05-17-2018

Re: Using PMOD pins as input

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After going through more forums, i found the issue and somewhat solution.

It seems the VCU118 outputs 1.2V from the level shifter and you need to use the 3.3V on pin 11 and 12 to pull up the 1.2V signal.

Seems people have been setting up pull up resistors using the 3.3V to solve this issue.

It's strange that the VCU118 doesn't incorporate this pull up internally and require us to do it externally.

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Observer
Observer
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Registered: ‎05-17-2018

Re: Using PMOD pins as input

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Had to use a pull up resistor with the 3.3V pin that they provide to pull up the 1.2V/1.8V signal coming out of the PMOD pins to 3.3V.

 

View solution in original post