Open richgel999 opened 9 months ago
jeffpc
commented
9 months ago I've gotten two BX boards from Mouser recently and they both fail to finish the USB handshake (https://github.com/tinyfpga/TinyFPGA-Bootloader/issues/74). Additionally, they both have 5V on the 3.3V rail. There are no shorts between the two rails; the 1.2V rail is spot on. So, I also suspect that the MIC5504-3.3YM5 voltage regulator is bad.
leaningktower
commented
8 months ago Hi jeffpc, I found the same issue as you mentioned recently and I also can not find a short. I found this problem because I want to use an external clock input and it turns out I need at least 5 V to make the it work and it turns out the 3.3 V is totally wrong. After simple testing, I am also pretty sure the LDO is not broken but it is a different LDO rather than the MIC5501 in the schematic. The code on the 3.3 V LDO is g5k, and it turns out to be AP2210K-3.3. However, the pin 4 of this LDO is not NC pin and can not be connected together with the VOUT pin 5. And that is why the LDO gives an saturated output that looks like a short. The simple solution I did is cut the pin 4 and 3.3 V is back.
jeffpc
commented
7 months ago Good catch! Both of my boards have a 3.3V regulators marked G5K. I cut pin 4 on one and now the 3.3V rail is 3.3V like it should be. Sadly, this didn't fix my other problem (USB handshake).
leaningktower
commented
7 months ago I purchased my board through crowd supply and waited it for at least 6 months. I am also suffered from handshake issue and use the dirty method mentioned by one of the post here. I guess all the broad shipped middle this year suffered from the same issue. Unfortunately I mistakenly broke the FPGA today, instead of waiting for the crazy lead time, I decided to purchase several iCE40LP8K chips and BGA soldering tools.
jonathancollins514
commented
6 months ago 
arndgo
commented
2 months ago Thanks, works. Getting 3.3V now. Great work.
I first had to work around the "no metadata" issue (by modifying a python file, as others describe). I'm now able to program the FPGA using the default template and I see the boot LED blink "SOS".
I noticed that both LED's are extremely (too) bright, which is odd. They've always been this way since when I first plugged it in.
I measured the 3.3v pin (pin #25), and it's measuring 5v when plugged into USB. If I unplug USB and supply 4.5v to the "in" pin, I get 4.5v at the 3.3v pin. The 3.3v regulator doesn't appear to be working.
I'm at a loss at what to do now. Perhaps try another platform.