How to get source file of PYNQ image

Hello,
Could you advice abobe 2 questions for me ?

  1. How do I get the source code?
  2. How do I create an image file using the modified source code?
    Image Version:V2.1
    Board:PYNQ_Z1

I would like to fix PYNQ USB to FS mode for evaluation.
Specifically, create an image file in which bit1,0 of TUSB1210 register “FUNC_CTRL” (Address0x04) is changed from 0x00 to 0x01.

PYNQ source code: GitHub - Xilinx/PYNQ: Python Productivity for ZYNQ
Why do you want to do this for v2.1? v2.5 is the latest image.

USB mode should be set to High Speed for the Z1 board. Are you trying to reduce the speed by setting to Full Speed? Why would you do this?

Cathal