HypnoToad
Posts: 77
Joined: Thu Dec 11, 2014 6:00 pm

Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 1:01 am

As soon as I power it up I get both on board LED's light up and stay on. Most info says this is due to the SD card not being found.

I've tried the same (official) PSU and SD card in another working RPi3, so it have to be the RPi2 PCB at fault. The SD card slot physically looks good.

Using a Multimeter, I measured the voltages at the various 'PP' test points listed here:

http://ozzmaker.com/testing-points-raspberry-pi/

Most of them tested as expected, but PP27 VBUS (USB 5V power) - measures 0v!

I tried plugging in a USB device, and no power whatsoever.

So this could be stopping it from booting?

If so is there a recommended fix? What would happen if I put a wire from the 5V GPIO to the PP27 pin, would it damage it further?

I'm not opposed to soldering but I can't really do small SMD stuff, but could solder to PP27 if needed.

User avatar
rpdom
Posts: 15426
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 5:59 am

USB power on the Pi 2B is disabled until the Pi has started to boot, so that's not the problem.

Have you been through the "Not Booting" Sticky post in troubleshooting? (Which is probably where this post should be moved to).

User avatar
jbeale
Posts: 3499
Joined: Tue Nov 22, 2011 11:51 pm
Contact: Website

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 6:02 am

I just totally changed my reply, because I believe the photo of the board in the test point link you provide may be a R-Pi 3 (?)

Just be sure which model Pi you are trying to use; by now I have forgotten how many different Pi varieties there are. I checked one under my desk that I thought at first was a Pi 2 but is in fact a B+ V1.2 which does have the numbered test points on the back (unlike the original Pi B which had no test points). On the B+ v1.2 board PP27 exists, but it is simply connected to GPIO21 (physical pin 40, at the bottom outside edge of the GPIO pins) and that is clearly not USB power. Unless you program it differently I would expect that test point on the B+ v1.2 board to be 0 V at bootup.

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 12351
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 9:46 am

moved thread to troubleshooting.

don't start messing up your PI, start reading the boot problem sticky in troubleshooting. https://www.raspberrypi.org/forums/view ... 28&t=58151

you can use this to correctly identify your PI first: https://raspi.tv/2018/new-raspberry-pi- ... us-zero-wh

HypnoToad
Posts: 77
Joined: Thu Dec 11, 2014 6:00 pm

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 10:42 am

rpdom wrote:
Mon Jul 29, 2019 5:59 am
USB power on the Pi 2B is disabled until the Pi has started to boot, so that's not the problem.

Have you been through the "Not Booting" Sticky post in troubleshooting? (Which is probably where this post should be moved to).
Hi yes I have - basically both LED's on = SD card not found.

My SD card and PSU both work perfectly on another Pi.

That thread did mention this however:

"Booting on a Pi is multi-phased: the majority of the boot process is executed by a small dedicated processing unit (CPU) inside the VideoCore GPU and consist of several stages. The Broadcom SoC contains a very small permanent memory which obtains the code to boot the device. First, it uses simple USB code to try to read a file pushed to it through the USB hardware. If this is unsuccessful, the code aborts, and uses its MMC hardware to attempt to read a file from a MMC compatible device. On the Pi, this is the SD card; the file should be on a FAT16 or FAT32-compatible filing system, and is called bootcode.bin. "

I have not tried USB boot yet - Does anyone know anything more about the 'simple USB code to try to read a file pushed to it through the USB hardware' method? This is the first time I've heard of this.

jbeale wrote:
Mon Jul 29, 2019 6:02 am
I just totally changed my reply, because I believe the photo of the board in the test point link you provide may be a R-Pi 3 (?)

Just be sure which model Pi you are trying to use; by now I have forgotten how many different Pi varieties there are. I checked one under my desk that I thought at first was a Pi 2 but is in fact a B+ V1.2 which does have the numbered test points on the back (unlike the original Pi B which had no test points). On the B+ v1.2 board PP27 exists, but it is simply connected to GPIO21 (physical pin 40, at the bottom outside edge of the GPIO pins) and that is clearly not USB power. Unless you program it differently I would expect that test point on the B+ v1.2 board to be 0 V at bootup.
Interesting I was under the impression that all full size Pi's with 40 pin GPIO's use the same PP test points, from the link I posted.

'Below is a list of test points which can be found on Raspberry Pi 2, 3 and some are also on b+.'

However it's just a random site so not guarenteed to be correct - I'd be interested to know of the other PP test points for the other boards.

On my board is says 'Raspberry Pi 2 Model v1.1' so I think it's one of the earlier Pi 2's, and PP27 seems to be connected to the USB 5V pins.

mahjongg wrote:
Mon Jul 29, 2019 9:46 am
moved thread to troubleshooting.

don't start messing up your PI, start reading the boot problem sticky in troubleshooting. https://www.raspberrypi.org/forums/view ... 28&t=58151

you can use this to correctly identify your PI first: https://raspi.tv/2018/new-raspberry-pi- ... us-zero-wh
Thanks for putting it in the right section. Looks like I have a RPi 2B a10141. :)

I've gone thru the boot problem sticky and tried everything apart from somehow booting using USB instead of SD card, but there are no instructions on how this is done in the thread.

There is no USB power when powered up on the Pi, I found a USB lamp thing for testing so I'm not even sure the USB boot method would work here without USB power on the Pi's pins.

User avatar
rpdom
Posts: 15426
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 10:54 am

The Pi 2B* doesn't support USB boot without some files on the SD card. Currently only the Pi 3B+ support booting from USB/Network without the SD card. It is optional to set that functionality on the 3B, but is permanent once set. The 4B doesn't have that option yet.

* I'm not sure about later versions of the Pi 2B which used the same chip as the 3B. That might be an optional thing too, but would require at least one boot from SD card to set the option.

HypnoToad
Posts: 77
Joined: Thu Dec 11, 2014 6:00 pm

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 12:39 pm

rpdom wrote:
Mon Jul 29, 2019 10:54 am
The Pi 2B* doesn't support USB boot without some files on the SD card. Currently only the Pi 3B+ support booting from USB/Network without the SD card. It is optional to set that functionality on the 3B, but is permanent once set. The 4B doesn't have that option yet.

* I'm not sure about later versions of the Pi 2B which used the same chip as the 3B. That might be an optional thing too, but would require at least one boot from SD card to set the option.
Hi maybe when I said USB boot I was using the wrong term. In the boot sticky post mentioned above there is this sections which applies to all Pi's as far as I know
Boot sequence details
Booting on a Pi is multi-phased: the majority of the boot process is executed by a small dedicated processing unit (CPU) inside the VideoCore GPU and consist of several stages. The Broadcom SoC contains a very small permanent memory which obtains the code to boot the device. First, it uses simple USB code to try to read a file pushed to it through the USB hardware. If this is unsuccessful, the code aborts, and uses its MMC hardware to attempt to read a file from a MMC compatible device. On the Pi, this is the SD card; the file should be on a FAT16 or FAT32-compatible filing system, and is called bootcode.bin. At this point, the ARM CPU is still in reset, so the contents of bootcode.bin are executed by the dedicated processor of the GPU: this code has more smarts, and can read the next file called start.elf, which in turn reads and interprets config.txt. It configures things like memory and Video/HDMI modes, console frame buffers, tests the GPU (resulting in the "rainbow screen"), and then handles the loading and configuring of the Linux Kernel (addresses, device tree, uart/console baud rates and suchlike). Only after this is the ARM CPU started, to execute the kernel code.
I want to try 'First, it uses simple USB code to try to read a file pushed to it through the USB hardware.' method of booting as this Pi doesn't seem to be able to find/read/use the SD card.

The sticky says how the boot process works, but gives no details on how to set up the USB partitions and filesystem. If anyone has managed it, then I'd quite like to try it. :)

drgeoff
Posts: 9901
Joined: Wed Jan 25, 2012 6:39 pm

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 12:49 pm

An original versions of the 2B requires boot files on a micro-SD card in the micro-SD slot. Without that it has little more functionality than a red LED.

Look at the numbering on the Broadcom chip - the large square one. 2836 is the original. 2837 is the later version.

HypnoToad
Posts: 77
Joined: Thu Dec 11, 2014 6:00 pm

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 2:01 pm

drgeoff wrote:
Mon Jul 29, 2019 12:49 pm
An original versions of the 2B requires boot files on a micro-SD card in the micro-SD slot. Without that it has little more functionality than a red LED.

Look at the numbering on the Broadcom chip - the large square one. 2836 is the original. 2837 is the later version.
It seems I have the early version, my chip says BCM2836:

Image

Does this mean the part in the sticky which says 'First, it uses simple USB code to try to read a file pushed to it through the USB hardware.' does not apply to this model?

User avatar
rpdom
Posts: 15426
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Found a RPi2 while cleaning out, however it does not boot!

Mon Jul 29, 2019 2:24 pm

HypnoToad wrote:
Mon Jul 29, 2019 12:39 pm
'First, it uses simple USB code to try to read a file pushed to it through the USB hardware.'
That only applies to Pi that can be used as USB device, not host. That means the Zero, CM and A models only. The B models do not support it.

Possibly the Pi 4B may support it through the USB2 port on the USB-C connector. I'm not sure as the boot code is different on that one.

HypnoToad
Posts: 77
Joined: Thu Dec 11, 2014 6:00 pm

Re: Found a RPi2 while cleaning out, however it does not boot!

Tue Jul 30, 2019 11:02 am

rpdom wrote:
Mon Jul 29, 2019 2:24 pm
HypnoToad wrote:
Mon Jul 29, 2019 12:39 pm
'First, it uses simple USB code to try to read a file pushed to it through the USB hardware.'
That only applies to Pi that can be used as USB device, not host. That means the Zero, CM and A models only. The B models do not support it.

Possibly the Pi 4B may support it through the USB2 port on the USB-C connector. I'm not sure as the boot code is different on that one.
That makes sense, that's a shame this method won't work on the B models. Still, I'll have to try the USB method sometime on the Pi Zero if I ever get issues with that. :)

I've given up trying to make this thing boot for now, I've run out of things to try but it most definately some sort of hardware issue.

Return to “Troubleshooting”