Jump to content
  • 0

Zedboard Power LED doesn't turn on, and can't boot but all 8 (LD0 - LD7) LEDs turn on


PJAB

Question

Hi, 

The main issue I have is currently the Zedboard doesn't even boot up and the power LED doesn'/t turn on. Instead when I connect the power adapter, all 8 of the LEDs turn on.

I was using this tutorial I found: https://www.hackster.io/adam-taylor/signal-processing-with-xadc-and-pynq-3c716c. Using the same IPs but different board file, basically just following the general structure. After programming the Zedboard everything was fine, and I connected the V_n and V_p inputs (pins 1 & 2 ) to a analog signal generator, which as set to 0.5v. 

The next parts however are quite hazy for me because it was in the spur of the moment, I think I pressed the PS-RST button and suddenly all the LEDs turned on or before I pressed it it was already like that. And since then it's been stuck in that way and unusable at the moment.

I've found a similar post on this forum relating to the same issue and followed it, however as I'm just a student I'm lost on the next steps. I have found that the IN4- < IN4+ for the IC29, and in turn traced it to IC27 where the C340 is around 0V. However from here I'm not sure what steps I need to perform in order to fix this. Below I have referenced the 2 forum entries I have read through and tried to follow. I apologize in advance if my explanation of my situation isn't clear enough, please let me know if there are more details I should provide. 

https://community.element14.com/products/devtools/avnetboardscommunity/avnetboard-forums/f/general/36514/zedboard-leds-on-power-up-board-not-booting

 

Thank you for taking the time to help me.

Link to comment
Share on other sites

2 answers to this question

Recommended Posts

  • 0

Hi @PJAB,

I'm not certain why the Zedboard is having this error. The only way the user LEDs would be lighting up would be if their 8 associated pins on Bank 33 were outputting a logic high signal. The tutorial you were following should be an issue and at first glance any of the actions you took should not be a problem. I will continue to look into this and see what I can come up with.

Thanks,
JColvin

Link to comment
Share on other sites

  • 0

Hi @PJAB,

Pushing the PS-RST button should (realistically) not have any effect on what was being applied to the dedicated analog inputs on the Zynq hardware, so I am doubtful that it would have any impact on the state of the power supplies.

You described IN4- being at a lower voltage than IN4+, which would result in OUT4 being a logic high (section 7.4 of the LM339M datasheet from TI), which would be what we want in this situation (have PG-ALL be logic high on OUT2).
For PS-POR-B output on OUT3 be low, the PG-ALL input on IN3+ needs to be less than the VREF3V0 on IN3-. PG-ALL is dependent on the 3.3 V rail, the 1.5 V rail, and the PG-DDR (dependent on Vcc 3v3 and Vcc 1v5) being at a higher voltage than ~0.9 V that is voltage divided from 3.0 V Vref (I'm getting all this information from the top right corner of page 16 of the schematic: https://digilent.com/reference/_media/reference/programmable-logic/zedboard/zed_sch_rev_f1-public.pdf).

Tracing farther back, the "short" version is that both the 3.3 V and 1.5 V rail are dependent on the PG-1V8 signal, the 1.8 V rail is dependent on the PG-1V0, the 1.0 V rail is dependent on PG-5V0, which of course is dependent on the 12 V power supply.

All this to say is that to find the root cause of failure, we will need more than just the voltage across C340.

In the interest of determining what all is happening on the power regulators, could you check the voltage on the following capacitors while the system is connected and powered?

Near IC27 on the bottom left on the underside of the board:
- C330 (should be 5V):
- C335 (should be 3.3V):
- C340 (should be whatever VADJ is set to):
Near IC28 on the bottom right on the underside of the board:
- C351 (should be 1.5V):
- C356 (should be 1.0V):
Near IC29 on the center right on the underside of the board:
- C368 (should be 5V):
Near IC30 on the top left on the topside of the board:
- C366 (should be 1.8V):
- C369 (should be 5V):
Near IC30 on the top right on the underside of the board:
- C388 (should be 12V):
- C392 (should be 5V):

Thank you,
JColvin

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...