A20 : I just get blinking lights. Help appreciated !

[otyugh]

Hey,
I bought to olimex :
>Power supply 12V
>LCD 10"
>A20
>micro SD pre-flashed 

With theses stuff I SHOULD be able tu boot, right ?
But I don't.

So let's debug with this other thing I bought :
>serial-USB-f 
I should be able to get some logs at least, right ?
NOTE : I found absolutely NO TUTORIAL how to get proper logs from the A20 on a debian image


I tried this :
┌──[otyugh@platinePc ~/Bureau]
└──$ lsusb
Bus 009 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 007 Device 005: ID 067b:2303 Prolific Technology, Inc. PL2303 Serial Port
Bus 007 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 011 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 010 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 008 Device 002: ID 0458:003a KYE Systems Corp. (Mouse Systems) NetScroll+ Mini Traveler / Genius NetScroll 120
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

##Serial Port is pluged, ok


┌──[otyugh@platinePc ~/Bureau]
└──$ ls /dev/tty*
/dev/tty    /dev/tty19  /dev/tty3   /dev/tty40  /dev/tty51  /dev/tty62
/dev/tty0   /dev/tty2   /dev/tty30  /dev/tty41  /dev/tty52  /dev/tty63
/dev/tty1   /dev/tty20  /dev/tty31  /dev/tty42  /dev/tty53  /dev/tty7
/dev/tty10  /dev/tty21  /dev/tty32  /dev/tty43  /dev/tty54  /dev/tty8
/dev/tty11  /dev/tty22  /dev/tty33  /dev/tty44  /dev/tty55  /dev/tty9
/dev/tty12  /dev/tty23  /dev/tty34  /dev/tty45  /dev/tty56  /dev/ttyS0
/dev/tty13  /dev/tty24  /dev/tty35  /dev/tty46  /dev/tty57  /dev/ttyS1
/dev/tty14  /dev/tty25  /dev/tty36  /dev/tty47  /dev/tty58  /dev/ttyS2
/dev/tty15  /dev/tty26  /dev/tty37  /dev/tty48  /dev/tty59  /dev/ttyS3
/dev/tty16  /dev/tty27  /dev/tty38  /dev/tty49  /dev/tty6   /dev/ttyUSB0
/dev/tty17  /dev/tty28  /dev/tty39  /dev/tty5   /dev/tty60
/dev/tty18  /dev/tty29  /dev/tty4   /dev/tty50  /dev/tty61

##Ok, so it seems ttyUSB0 is what I'm looking for

I now pluged the serial-USB-f to UART0
RX -> green cable
TX -> red
GND -> blue

Then I installed putty but could not make it work (maybe a bug from arch repository).
So I tried minicom :
""
sudo minicom -b 115200 -o -D ttyUSB0
""
and screen
""
sudo screen ttyUSB0 115200
""

The SD I used is a micro SD class 10 of 8Go. I flashed it using "dd if=/path/to/debianfromolimex.img of=/dev/sdX" then "sync".
My image :
┌──[otyugh@platinePc ~/Bureau]
└──$ sha512sum A20_debian_kernel_3_4_LAN_USBx2_Cards_LCD_HDMI_SATA_TS_X_GPIO_OTG_MIC_Video_accel_release7.img
d6f49fc6e31685e3f5b3b5ad198a86950238a38d0beb6f72d616f0d8145e2865af8d4bcc20210f339d0a77b7162d6e522501f376fbc02537b694a2f75da1b4e5  A20_debian_kernel_3_4_LAN_USBx2_Cards_LCD_HDMI_SATA_TS_X_GPIO_OTG_MIC_Video_accel_release7.img

Then I tried to plug the power supply 12V of yours in the A20. Lights go on, blinks.
No output at all to my PC.

What Am I doing wrong ? Or Am I not doing anything wrong, and the device is broken ? I'm put a lot of faith in this and I'm near to say "it just don't work" ! :s

Please help

[martinayotte]

Hi,
Just to make sure, did you tried to reverse TX/RX wires ? (since the manual said the following)

"Consider table below when connecting the USB-SERIAL-CABLE-F according to the wire color
code. The RX line of the cable (GREEN wire) should go to TX line of the target board; the TX line
of the cable (RED wire) should go to the RX line of the target board. The BLUE wire should go to
the target's GND line."

Also, either you use minicom/putty/gtkterm (personnaly I prefer gtkterm), make sure you provide the full path of the serial port, ie. :
gtkterm -p /dev/ttyUSB0 -s 115200

Hoping this help,

[otyugh]

I just did what you said (and indeed, I prefer this one). But no output either (launched your command, powered the A20 on, switched them. Unpluged the power, restarted it. Nothing on the screen so far :s

Is there a way to check if I'm doing this properly ? As I did not get any output from the start, I suspect it could come from me.

Thanks for the answer !

[Lurch]

Can't help with linux-PC, I use Windows and Putty or Tera Term with 115200, 8, 1
All three of my A20's boot the Linux image you used. If you are doing it blind, them you should see the red LED go on with the power and the green LED start blinking in 1-second tact if the board starts booting.
If you turned off or reset the board while it was actually booting (or after it booted) then you may have corrupted the SDCard image on the running system - in which case you will have to re-flash the SDCard.
The power should be 12V with at least 1-1.5A (I use 2A since I sometimes use the 10" LCD and have a 2.5" SATA drive attached)
I had an Olimex USB-TTL, but the PL2303 driver was messed up, so I use other little boards that have Tx and Rx LEDs, so you can see if traffic is going through.
Do you see any activity on the ethernet link-LEDs on the board when trying to boot?

[otyugh]

I was used to unplug a lot the raspberrypi in all sort of way without corruption (...yet), so I forgot that.

The power supply I'm using is the following : https://www.olimex.com/Products/Power/SY0612E/


I could use my windows partition to try again. Bu first of all I'll reflash my SD card and try martinayotte way.


I just find it very odd that NOTHING displays with the serial in my console, but the lights glitters as you mentioned (and as long as I can tell, only the power led and a green light pulse).
I don't plug the ethernet cable. I thought it could be a source of potential trouble. I just plug a microSD card, power supply, and the usb-serial

Then in dispair, I'll maybe try out on the microsoft side.

[JohnS]

I use Linux with an A13:
screen /dev/ttyUSB0 115200

I've not used the SD card image you use so don't know whether yours tries to log anything to its console during booting.  The A13 ones I use all do.

I use cheap USB-serial devices, they just work (for me).  Easily tested by connecting Tx to Rx.

John

[otyugh]

I use cheap USB-serial devices, they just work (for me).  Easily tested by connecting Tx to Rx.

What do you mean by connecting Tx-Rx, the two of them are female, right ?


I have to ask
on the A20
if the red light is on ; the power is ok. And if the green light is "1 sec up, 1 sec down, 1sec up..." it means that... ?
The ethernet light pulses one time when pluged, also. Dunno what it means.
...Still no output, tho.

and what should I do to shutdown it without having to reflash the microSD as I have no idea what it is doing?

[martinayotte]

What JohnS said is that he is using cheap USB-Serial found on eBay instead of the Olimex one. Those are usually male connector with small female cables.
So, to test if your Olimex USB-Serial, which has built-in cable with female connectors, you should short the green and red cable with a piece of wire. Then, using gtkterm or minicom, you can test this USB-Serial, it should echo all your typing to yourself. If it doesn't work, that will explain why you didn't have any output earlier, probably this device is defective. If it works, we still need to figure out, because even if the board is not booting, you should see few lines where uBoot trying to get an image from SD or Nand.

[otyugh]

How can I ?
I mean : I put one terminal to "screen /dev/ttyUSB0 115200", put a wire trough Tx-Rx, then how do I type anything to myself ?

[martinayotte]

What I was saying is to verify the USB-Serial is working properly. Simply connect RX-TX of the USB-Serial with a small wire, without any Olimex board connected. Then, whatever you type in gtkterm will be locally echoed, since the wire will do a loopback. If it doesn't, then either USB-Serial is defective or there is a problem with the software, maybe permissions on /dev/ttyUSB0.

[otyugh]

Connecting RX to TX seemed to work : I could type and I could see what I was typing.
But.
As I unpluged them, I tried to type again... What was my surprise seeing I could write (it was strange letters, tho). But well... The USB-serial-f of olimex was not okay...



Back to my problem, I was awesomly helped by a user that told me to mount a microSD on my computer, put the debian image to "connnect the network "... And I just did everything by SSH. Then /root/change_res.sh was enought to make things just work.

<lukas2511> mount the microsd card, edit [yourmountpointhere]/etc/network/interfaces
<lukas2511> add:
<lukas2511> auto eth0
<lukas2511> iface eth0 inet dhcp

then ssh the A20, and win.

* otyugh praise lukas.