Yes, from that and the https://www.raspberrypi.org/documentati ... teeprom.md all tends to indicate corrupted EEPROM. The problem here is that I can't manage to rewrite the eeprom following that procedure.Imperf3kt wrote: ↑Tue Oct 08, 2019 2:35 amI assume you've read the Pi4b section of the.boot sticky?
https://www.raspberrypi.org/forums/view ... 1#p1485558
Are you able to measure the SD clock and command lines ? Best guess is that some fault related to the sd-card which has caused the ROM to hang and fail to proceed to the EEPROM, although I've never seen this when the sd-card slot is empty.iosabi wrote: ↑Tue Oct 08, 2019 12:08 pm"Does this happen if you remove the SD-CARD and power on ?"
Yes, same symptoms with or without an sdcard installed.
I probed around the EEPROM with the oscilloscope and found out that the EEPROM is not even read:
1) On my healthy Pi4B without an sdcard, when probing the #CS (pin 1) and CLK (pin 6) of the chip labeled 4H916 next to the AV jack, I see the following sequence:
* #CS stays up for ~100ms, then down for ~180 ms while the EEPROM is read
* CLK goes up for ~12ms, then down for 90ms, then I see a clock of about 3.5MHz with ~1 clock pauses every 8 pulses. This is clearly reading the EEPROM (it looks to me like less than 4Mbit, but didn't measure super accurately)
2) On the other Pi4B, again without the sdcard at all I see:
* #CS goes up and stays there forever (2s+)
* CLK goes up for ~12ms, then down forever
The pi then sits there draining 300mA @ 5V. Nothing obviously dead in the power side.
The green LED blinks very briefly, I measured ~12ms but this happens very early. It starts ~70ms after applying power to the 5V rails in the GPIO header. This is at the same time that CLK goes up for 12ms, so well before we even read the EEPROM (which doesn't happen in the broken Pi4B).
Is there anything earlier than the 4Mbit EEPROM that could be broken? Any hints on how to debug this?
This rpi4 is new, I have booted it only a few times before and if I remember correctly it broke when updating the eeprom from the running OS.
I created the sdcard in linux with gparted, selecting fat16 or fat32. I also tried formating the partition with mkfs.fat which lets you force fat16 or fat32.
I don't think there's much more that you can do to debug it. However, we'd be interesting in getting the board back so that our hardware engineers can take a look. We'll send you a replacement + Pi goodies to cover the postage & hassle.iosabi wrote: ↑Wed Oct 09, 2019 9:30 amTimg236, first of all thank you for following up on this issue. Really appreciate your time looking into it.
I measured the sdcard slot lines without any sdcard in it. All of them remain low, except for the sdcard Vdd which comes high (3v3) ~70ms after power is applied to the 5v lines in the gpio port.
In the healthy pi4b i also have, I see a clock in the CLK line after about 15ms of sdcard Vdd coming up, but this doesn't happen on my other pi4b. I don't see any physical damage, and as I say I was trying to flash the new eeprom from a booted OS when this stopped working.
Is there any JTAG or other debug port I can look at for the main cpu?
It's not easy to spot on that photo either - is it the thing to the left of the 2D barcode label?timg236 wrote: ↑Tue Oct 22, 2019 11:20 amThe reason that the board was no longer booting is that a resistor had become dislodged which prevented the SOC from powering up properly. It's a tiny resistor so not easy to spot but I've attached an image showing where it was re-worked which allowed the board to boot and run Raspbian. The bootloader EEPROM seemed to be fine.
N.B. The brief flash of the green LED at power on is just due to the power sequencing rather than the ROM enabling it.
https://drive.google.com/open?id=1KtjSr ... begfSVrWDe
I was under the impression that all boards were individually tested at the factory, but I may be wrong. It perfectly possible that it was attached firmly enough to test OK then due to mechanical stresses, vibration etc somewhere along the way came loose.
Even with this, nothing seems to work for me. I tried different cards, different power supplies etc. My green LED will NOT blink. It will not do anything, and the red LED will just stay on. Is this a native problem in RPi 4?
Looks like a broken device. If you have tried all that stuff and it still doesn't work.spandananupam wrote: ↑Mon Feb 03, 2020 7:36 pmEven with this, nothing seems to work for me. I tried different cards, different power supplies etc. My green LED will NOT blink. It will not do anything, and the red LED will just stay on. Is this a native problem in RPi 4?
Nope. I have a Pi3, which goes in a loop of green when the SD card isn't installed. This one, however, doesn't do anything. There is a very short pulse of green light that comes up only at the start and that's about it. It's completely red after that.jamesh wrote: ↑Mon Feb 03, 2020 9:05 pmLooks like a broken device. If you have tried all that stuff and it still doesn't work.spandananupam wrote: ↑Mon Feb 03, 2020 7:36 pmEven with this, nothing seems to work for me. I tried different cards, different power supplies etc. My green LED will NOT blink. It will not do anything, and the red LED will just stay on. Is this a native problem in RPi 4?
With no SD card in and power up, do you get any green flashes?
I did test my flashes on a different Pi3. It boots up fine and goes through the usual. There is something very specific with this Pi4. I do not know if anything can or cannot be done but in the distant case it can be, I will have to try because these cost a lot here in India. If taking this or mailing this into some shop will do the job, then that might be a lot cheaper.Moonmarch wrote: ↑Mon Feb 03, 2020 10:35 pmAny LED not blinking or staying on does not mean your RPI computer is broken if you are using a laptop that uses LED lights to tell you when CAPS LOCK or NUM LOCK is on, then you replace the keyboard with a third keyboard that does not have any LED lights you can't assume the keyboard is broken no instead you would say the third party keyboard has less features, because you decided to purchase a cheap replacement keyboard for the laptop, if the LED does not turn on when you use CAPS LOCK check to see if CAPS LOCK is on use a text editor Mousepad then write in the text file to see if CAPS LOCK is actually on.
When you start the RPI computer for the first time the boot up can take a long time after the first boot after downloading, and installing all of the updates the RPI computer should boot faster afterwards, if you do not know how to flash the Raspbian OS image to a SD card then you would need to purchase a SD card that contains NOOBS, after booting the RPI computer with the SD card that contains NOOBS if the computer refuses to start then your RPI computer is out the door, you need to replace the computer forget about soldering or using multimeters replace the computer, here is a link to a SD card for sale with NOOBS installed:
64 Gb micro SD For Raspberry Pi 4 / 3B+ / 3A+ /3B With NOOBS v3.2 (Ready To Use)
https://www.ebay.com/i/283491540894?chn ... 5HEALw_wcB