Monday, February 13, 2023

Setting up to pass address to FPGA and display that word - but gremlins pop up

SIMPLE WAY TO SHOW THE ADDRESS SENT TO THE FPGA SIDE

I decided to make use of the four dip switches and eight LEDs on the board as a way of displaying the address latched in my logic, that address updated when the HPS side Linux program sends a message with a memory address. 

The essential part for this first half of the project is to activate the lightweight HPS to FPGA bridge that supports communication between the Linux system and my logic. I only need this to send one word over the link, which is either all zeros or the virtual address in Linux where my memory mapped file is placed. 

Even more simply, I only need to get the virtual address of some one known word value, then send that address over the bridge to the FPGA side. If I observed that the address was properly transferred, I could consider this essential functionality operational.

FIGHTING TOOLCHAIN TO TEST

After many battles defining a system from scratch for the experiment, resulting in many failures in TCL scripts and failures to generate the VHDL for the system, I threw in the towel and decided to hack on the existing 'golden' reference files as everyone else seemed to do. 

That didn't work - similar errors. Okay, lets just generate the golden reference file as it sits, unmodified, to make sure that the environment is sound before I introduce any of my own changes. Failure! 

At this point I am going to transition to full on internet idiot mode. I will follow the reference document step by step, clicking and typing exactly as they do, hoping to at least get the demonstration project to be generated. If so, then I can differentially analyze it to figure out where I went wrong. If it won't work here, perhaps my platform is corrupt and I should work on another laptop. 

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