Closed dixi83 closed 11 months ago
The version I have is a 8.2. As far as I could determine it has the same pin assignment as documented for the 7.1. I have only tested the RGB pins not A-E...
Hi,
at least on my board which is V7.0 some FPGA-pins are connected to multiple output buffers. This could lead to some short-circuits if not taken care of. Just a thought. Also maybe the buffers are crap, i would recommand buying them from a reputable source like Mouser, Digikey, Newark/Element14/Farnell, ... depending on your location in the world.
I have a file !!!FOR VERSION 7.0!!! which shows what is connected where. Il will add it to my github, might be useful for other people.
Also i would suggest removing all the buffers with hot air and see if the FPGA (not CPU) works again.
EDIT: Other thought: Did you remove the FLASH-memory that contains the original/default bitstream? This bitstream might configure some FPGA-pins that are now inputs on your board as outputs, this is a problem. You can remove the FLASH-memory so the FPGA will power up unconfigured and you have to flash it first via JTAG (NOT persistent). I did this and it works fine (V7.0). Details on my github.
@kittennbfive thanks for your reply! I ordered a new card from Ali and also some new IC's from Farnell. I will do a retry next week is I have more time. I will use kapton tape to isolate Pin 1 and 20 it looks really neat. I did not removed anything else then the buffers with a wire attached on the photo... what I do know now I should not have removed the buffers I wanted to keep as output. I did used a hot air gun. I only used a iron for cleaning the pads and some solder removal lint (not sure if it is the right English word) Sorry for shouting "CPU" to a FPGA... I was not aware 🤣
@everyoneelse this is the repo kittennbfive is talking about: https://github.com/kittennbfive/5A-75B-tools I received my new card last week. I also ordered a mesa card to get started with my machine and getting used to the way of configuring LinuxCNC.
The thing I did not mentioned in my previous post is that I did not even test the card before changing anything. so another option would be that my first card was death on arrival...
The word you are looking for is "solder wick". ;-)
As i said, you really (imho) should remove (or erase at least) the FLASH containing the default bitstream so there won't be any FPGA-pins fighting against the new installed buffers. Also you should check for FPGA-pins connected to multiple buffers for the same reason. I am afraid i can't give more details because i don't have a V8.
Thanks for your comment and extra warning. I think this is what went wrong.... I finally found what you meant: https://github.com/kittennbfive/5A-75B-tools/blob/8f4c14c88fb531b183f87d95d1defc01eb2f0712/I_want_inputs/README.md The next question is a noob question 😉 ... Can I "remove" the flash by compiling "empty" firmware and load this using openFPGAloader or is there a way to do this in another easier way?
EDIT:
openFPGAloader -c ft2232 --bulk-erase
will probably do the trick. Am I correct?
I would guess that simply erasing the flash should be ok, but honestly i don't know for sure. :(
Hi All, My first attempt replacing the buffers with the 74LVC245 failed... after replacing them the CPU gets really hot and does not respond any more to anything.... so I guess I fried it.
The idea was to make the J1-J8 input and leave the J9-J16 output I don't know what went wrong, I tested every IC after replacing for short circuit and between every pin. There are 3 options I see:
I ordered a new one but I don't want to fry my new one.
Thanks!