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I am a high school student, who is not very familiar with FPGAs and the Xilinx line.

I am running a ring oscillator module on a Zybo Z7 board. I am also running a counter module, which I want to sample at a high rate. I am currently sending the data through AXI to the ZYNQ processing system, and then using the inbuilt UART to USB buffer to send the data through a USB cable to my computer. On the computer side, I treat this input as a virtual serial line, and use a python script to take and log the data from an IOstream. This method takes very long, however, and I am trying to increase the sample speed. Thus, I was wondering if I could bypass the onboard PS, and connect the FPGA fabric directly to the UART buffer.

I have tried optimizing my PS code, which I have written in C. I have reached the point where it takes 30 oscillations of the onboard ZYNQ clock between samples. Now, however, I have created a newer and more reliable sampling framework in the FPGA logic, which requires a 'handshake' mechanism to start and stop the counter between samples. It takes a very long time for the PS to sample the counter, send the sample, and then restart the counter. Thus, the uptime of my sampling framework is a fraction of what I want it to be. Removing the PS would be ideal, as I know I can automate this handshake signal within the PL if I am able to connect it to a UART interface.

Rahul Jayachandran
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You can implement logic in the PL that can handle the UART communication thus bypassing the PS.

Here's an implementation you can try using:https://github.com/jakubcabal/uart-for-fpga

You would connect the UART pins to one of the Zybo Z7 Pmod ports and use an external USB to UART adapter such as this one, anyone would work as long it supports 3.3V: https://www.adafruit.com/product/5335

The adapter built into the board is connected to directly to the PS MIO pins and cannot be used by the PL.

Aaron Olivarez
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