mrosile813
Posts: 6
Joined: Sun Apr 18, 2021 7:02 pm

Undocumented RPi4 activity LED code?

Sun Apr 18, 2021 7:08 pm

I have a Raspberry Pi 4B that recently stopped booting (no video output from either HDMI port). The Activity LED shows 3 long, then 3 short blinks. Same thing happens with or without a micro SD Card inserted. The same micro SD card works fine in another RPi 4B.

I have not seen this exact LED sequence mentioned in the RPi documentation or sticky posts for this forum.

Can anyone tell me what 3 long and 3 short blinks means? And whether it's able to be fixed?

cleverca22
Posts: 3596
Joined: Sat Aug 18, 2012 2:33 pm

Re: Undocumented RPi4 activity LED code?

Mon Apr 19, 2021 7:30 pm

can you record a video of the blinking?

there was a bug at one point, that made an extra blink of a different length, which can make it a bit more confusing to read


MiscBits
Posts: 204
Joined: Wed Jan 27, 2021 12:48 pm

Re: Undocumented RPi4 activity LED code?

Mon Apr 19, 2021 9:59 pm

In the 4 boot sticky, there is this note:
Not blinking four times with nothing but the power connected (and no SD-card) implies that the bootloader is not working correctly and should be reinstalled using recovery.bin
Maybe start with that?

cleverca22
Posts: 3596
Joined: Sat Aug 18, 2012 2:33 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 1:08 am

that does look like a true 3long 3short code

is there an SD card present?
is a usb stick present?

mrosile813
Posts: 6
Joined: Sun Apr 18, 2021 7:02 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 1:26 am

Whether a working SD Card is present or not the result is the same. No, no USB devices connected. Power and HDMI are the only things connected, and even with only power the result is always the same.

mrosile813
Posts: 6
Joined: Sun Apr 18, 2021 7:02 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 2:58 am

@MiscBits I tried your advice, I attempted an eeprom recovery using the recovery.bin as detailed here, https://www.raspberrypi.org/documentati ... teeprom.md, and although the blinking stopped while the new SD Card was installed nothing else seemed to happen (no matter how long I waited (1+ mins)). Removing the SD card or using other valid SD cards returned the Pi back to the situation I am currently experiencing (3 long blinks, followed by 3 short).

cleverca22
Posts: 3596
Joined: Sat Aug 18, 2012 2:33 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 4:27 am

do you have access to a 3.3v uart adapter? or another rpi?

timg236
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 831
Joined: Thu Jun 21, 2018 4:30 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 11:02 am

It sounds like an I2C error (doc PR pending), it's very unusual (we've not seen it) happen every boot though.

The latest bootloader is more tolerant of transient errors.

Try using the Raspberry Pi Imager to write this image to a spare SD card as a "custom image" to update the bootloader to the soon to be default release.
https://github.com/raspberrypi/rpi-eepr ... 8a1-sd.zip

mrosile813
Posts: 6
Joined: Sun Apr 18, 2021 7:02 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 12:42 pm

Hi @timg236,
I used the RPi Image to write the supplied zip file to a spare 4 GB micro SD card. I verified the data was written to the card and plugged it into the RPi 4 in question, but the results are the same. 3 long blinks followed by 3 short blinks.

It doesn't appear to be triggering the recovery.

@cleverca22 asked about a UART adapter or another Pi. I think I have a 3.3v UART adapter, but I definitely have another Pi. If someone can provide me some basic instructions I can hook those up for additional troubleshooting.

timg236
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 831
Joined: Thu Jun 21, 2018 4:30 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 12:54 pm

mrosile813 wrote:
Tue Apr 20, 2021 12:42 pm
Hi @timg236,
I used the RPi Image to write the supplied zip file to a spare 4 GB micro SD card. I verified the data was written to the card and plugged it into the RPi 4 in question, but the results are the same. 3 long blinks followed by 3 short blinks.

It doesn't appear to be triggering the recovery.

@cleverca22 asked about a UART adapter or another Pi. I think I have a 3.3v UART adapter, but I definitely have another Pi. If someone can provide me some basic instructions I can hook those up for additional troubleshooting.
If it's doing this every boot with the default and the update recovery image then it could be a hardware fault communicating with the PMIC. The bootloader change for an approximately 1 in 1000 warm reboot failure on some boards.

cleverca22
Posts: 3596
Joined: Sat Aug 18, 2012 2:33 pm

Re: Undocumented RPi4 activity LED code?

Tue Apr 20, 2021 5:42 pm

mrosile813 wrote:
Tue Apr 20, 2021 12:42 pm
@cleverca22 asked about a UART adapter or another Pi. I think I have a 3.3v UART adapter, but I definitely have another Pi. If someone can provide me some basic instructions I can hook those up for additional troubleshooting.
the 2nd pi bit, was just a way to access the logs without a usb uart adapter

https://pinout.xyz/pinout/uart
if you hook the uart adapter up at 115200 baud, and then add "uart_2ndstage=1" to config.txt, then recovery.bin will print its own logs on the uart
that could help identify why its not performing recovery properly

mrosile813
Posts: 6
Joined: Sun Apr 18, 2021 7:02 pm

Re: Undocumented RPi4 activity LED code?

Thu Apr 22, 2021 6:18 pm

I connected a USB UART adapter, but no luck .. no output from the Raspberry Pi4 in question. I verified the adapter and my setup was working correctly using a known working Pi, so I think its safe to say this is truly a hardware malfunction.

I'm going to send this Pi4 in for warranty as it is not even 5 months old.

Thanks everyone for your help and suggestions!

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