Trouble

3 day old B-Pi seems to be dead......

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Reply 30# neditt

I change the power supply and sd card but nothing happened.
Only red led is light on nothing else.


@ neddit

I just did exactly the same as you today. Bought a new power supply from my local shop (but I could only get a 5 Volt/1 Amp for a reasonable price, and that was just over 20% of what I paid for the Pi - the previous PSU I was using was 5V/2A, 2 Euros mail order plus 3 Euros postage but it took over a week to get here).

I also bought 2 new 8GB SD cards (1 normal size, the other micro SD with adapter) and burned them with a fresh Raspbian image.

Tried booting with the 2 Amp PSU - only red light.
Tried booting with the new 1 Amp PSU - the same.
Tried with both PSU's plugged in to DC In and OTG, swapped them around - no boot.

Tried other distros such as Berryboot (because it's only about 66MB and quick to búrn).

What's going on here? How many of these defective Pi's are out there?

There must be a simple way to solve this.............

Post Last Edited by roses2at at 2014-9-24 17:19

Reply 1# roses2at

I was using Lubuntu when that OS crashed (mouse did not move cursor and clock time did not change for more than 30 minutes)

   
Now that I think about it, I seem to remember that there were some very strange almost psychedelic colour changes and rapid screen flickering just before it crashed.

What does that indicate do you think?



1) Defective RAM?

2) Power supply not up to the job? (Although I have to admit I was running it via a USB cable from a USB 3.0 PCIe add-on card on my PC for quite a while without any issues or strange burning smells. The card itself - or more correctly the PCIe slot - is itself powered from 4-way Molex connector coming from a 450W PSU. At the time of the crash however, I was using a 5V 2 Amp PSU which is still working and powering my R-Pi as I write this.....)

3) Maybe a dodgy or dry solder on the PCB? Someone on another forum who reported similar symptoms as neditt and myself said he had found a short circuit between two tiny pins on the A20 chip but I somehow find that hard to believe. But maybe it's worth doing a visual check with the aid of a magnifying glass over the rest of board.


Are there any test points on the B-Pi that I can check with my multimeter?




Reply 29# roses2at
So are you saying that this Section 6.2.2 on page 18 is wrong

I wouldn't dare....
Rather you have interpreted it wrongly.

The SoC does not incorporate the bootloader(Uboot) itself but only a mechanism to load uboot from a sdcard,NAND-Flash or over USB(by first switching to FEL mode), to memory.
After uboot is loaded to memory,it assumes control and then you could load and boot the os kernel etc as described in the text.
   
As for being stuck with windows,you could try a vm install of say Lubuntu using VirtualBox or VMware player.This way you could have the best of both worlds.

And the problem with your board seems more RAM/some-other-chip related rather than the sdcard-slot itself.
You can have a look at the schematics if you want to probe the board for voltages.

Reply 33# sashijoseph


   Well, in retrospect, maybe I did misinterpret that quote in Post #27 from Page 18/Section 6.2.2.
I thought it meant "you put the boot files on the USB stick, power up the Pi with the Uboot button depressed then release it, and it will boot up reading from the stick rather than looking first for the SD card". In other words, similar to a Windows machine where usually it boots up from a hard drive, but sometimes you want to boot up from a CD-ROM or a USB stick (eg installing a new OS or entering recovery mode or using a Live CD) so you press F11 or whatever during POST to choose the boot option. That for me would be a logical way to design a Pi, so that if the SD card slot fails (and let's face it, it's not the most robust or reliable of things), there are other possibilities of booting. Personally, I would do away with SD cards altogether, add two more USB ports (like the R-Pi B-plus) and only use USB sticks for booting. (Is there a technical reason why that's not possible? What's the raison d'etre for SD cards anyway? They cost per GB about the same as USB sticks don't they?)

What that quote actually means is you put the boot files on your USB stick, and then you have to tell the Pi where to find them and issue a command for that from a Linux PC - in other words, the loading of those boot files has to be INITIATED from another computer using the PL2303 from the PC's USB port into the J11 UART serial TTL port pins.

Or have I still got the wrong end of the stick? Perhaps you have to send those boot files from the PC into J11 and there is no USB stick connected to the OTG at all?

Anyway, when all's said and done, without a Linux computer a set of commands such as
  1. # usb reset
  2. # fatload usb [:partition]
Copy the Code


doesn't help me much as I don't know how (or if it's even possible) to do that in Windows.

Post Last Edited by roses2at at 2014-9-26 10:16

Reply 34# roses2at

You can have a look at the schematics if you want to probe the board for voltages.

   
Well, I found some schematics thanks to your Post #32 in this thread:
http://forum.lemaker.org/48-4-1-4.html

Download schematics from http://hardware-libre.fr/wp-content/uploads/2014/07/A20_Blockdiagramm_BananaPI.pdf

but they don't actually specify where the test points are for checking voltages or what values I should expect to find.

Reply 34# roses2at

Those commands you mention are issued from the uboot prompt,not a linux prompt.
Once uboot is running on the Pi and you manage to get to the prompt by interrupting (uboot's) autoboot sequence,you can issue those commands from a serial connection.
UBoot listens to the Pi's serial port for commands.At the other end of this serial connection there could be a linux or windows sytem,makes no difference.

The part where a Linux system is imperative,is for loading uBoot itself.This is done by the FEL binary which runs on Linux as of now,unless someone manages to port it to Windows.This FEL tool establishes a connection between the pc's usb port and the Pi's OTG port and transfers the uboot binary to the Pi through this usb link.

As for the direct boot from a usb stick,most embedded processors cannot afford the complexity of implementing a usb stack which would be required to access the pen drive containing uboot and the rest of the os.This complexity is handled by uBoot.
Flash memory/SD interface is relatively more simple and is thus preferred for atleast the initial part of the booting process(accessing,loading,running the bootloader).
Even on a PC the BIOS resides in Flash memory...the processor cannot boot from a usb stick directly...it first loads and executes the BIOS.

Can't comment on the unreliabilty of the sd socket as it's working fine on both my RPi and BPi,though onboard flash would've been a welcome alternate boot source.But at the price point of either Pi you can't really complain,can you?

Reply 35# roses2at

Unfortunately there are no convenient test points on the board.So you'll have to refer to the schematic and measure across components or pins which can be accessed easily.
Page6 depicts various VCCs  so you could measure say DRAM-Vcc(1.5v) across C88 or C90...yes it's mighty tedious and probably will not yield anything.
If I were you I would probably only check out the boot message on the serial port and return the board for a replacement.
   

And what about the virtual machine install?
Planning to go that route?

Reply 36# sashijoseph

Those commands you mention are issued from the uboot prompt,not a linux prompt....... could be a linux or windows syatem, makes no difference.

    Please excuse my total ignorance about these things - I hope you have now finally got over your fit of the giggles after reading that!!

My USB-TTL cable should have arrived today but didn't (maybe Monday). So if it was here, I would possibly be doing and learning those things for myself rather than writing such inane comments.

Reply 37# sashijoseph


  
Unfortunately there are no convenient test points on the board.

Well, on the underside of my board I can see TP2 (between the A20 chip and the GPIO pins) and also u14 5.0 V (between the DC In socket and SD card slot holder).

On the top side I see various others: VBAT, VBUS, IPS out, SATA, SD, 1.5V, MAC1, MAC2, AC In,...........etc.

What defeats me is how you're supposed to hold your multimeter probe onto a point on the PCB underneath (without it slipping off and shorting a component or track) while simultaneously doing the same with the other probe onto a point on the OTHER side of the board, and all the time with the Pi energised with 5V/2A...........unless you're an octopus. Maybe best left to the pros!!

For the R-Pi (mine's a B+plus), I'm sure I saw a web page somewhere with all those test points and what voltages should be there, all clearly marked and conveniently labelled.

Reply 37# sashijoseph


   
And what about the virtual machine install?



Well, I dabbled in VMs a couple of years ago using VMWare (can't recall exactly what I was doing or why, but it was unconnected to the Pi) but that was on 32-bit Windows. Now I'm on 64-bit and the software I have won't work with that.

If I did go anyway at all, it would be via a Linux distro Live CD (or from a USB bootable version thereof) but as I think I said before, I need to have constant Email and Internet access so I cannot really afford the down time and I have no other components left anymore to build another PC (and no dosh to buy them).

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