Any owners of HL-PC789 R1.0 WM8880 netbook?

[Fernando Cassia]

Hi

I have read many messages from this group, and I think this is the right place to ask, you have the programmers, and you have the guys with hardware knowledge like Alexey.
Hardware: HL PC789 R1.0 netbook It features a WM8880, 1Gig of RAM and 8GB Toshiba NAND for storage, shipped with Adroid Kitkat.

I wanted to begin experimenting with VT8xxx Linux kernel on this puppy but the hardware began failing before I even had the chance to do so.  First by randombly not booting and one day finally not booting at all.
To add insult to injury, there is no way to invoke the android repair menu as phones depend on one pressing power on + volume updown and there are no such keys on these netbooks (and believe me, I have tried every possible combination).

So here I am with a WM8880 device that boots with an animated logo until the point it ends with a black screen and ... nothing.
I ve tried installing ADB/Fastboot on a Win7 system and plugging the netbook with a USB male-male cable to no avail. ADB doesn t see any android device.
So by looking at the PCB I saw what looks like an unsoldered PCB header, with the only diffeerence that the D+ and D- pins are reversed. In other words, D- is next to VCC and D+ is next to GND which doesn't make sense for USB.

I wonder if this is some sort of RS232 port? or SPI?

I'm also curious if there's any affordable hardware interface allowing one to program the NAND storage "in place" just by affiing a reader/writer directly to the chip pins, without powering the whole board. Just thinking aloud, pershps there's an easier option.

In other words... WHAT WOULD ALEXEY DO? ;)

Thanks in advance for any insight
FC

[Adrien Destugues]

Hi,
IIRC, you should be able to put some u-boot boot script on an SD card and insert that in the SD slot (https://github.com/linux-wmt/linux-vtwm/wiki/Boot-from-sd-card). The script will then be executed.
Usually u-boot will look for keyboard input on the UART, but you can get it to use the display and keyboard of the netbook, or download something from the network, or boot Linux from the SD card.
From there you should be able to access the Android partition and see if you can do something with it.

The other option is locating the TTL UART pins or pads on your motherboard, and connect a TTL serial adapter to it. There you can see logs from Android booting, and maybe reach a shell.

--
Adrien.

> --
> You received this message because you are subscribed to the Google Groups "VT8500/WM8505 Linux
> Kernel" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to
> vt8500-wm8505-linux...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.

[Fernando Cassia]

On Fri, Oct 7, 2016 at 4:23 AM, Adrien Destugues <pulko...@pulkomandy.tk> wrote:

Hi,
IIRC, you should be able to put some u-boot boot script on an SD card and insert that in the SD slot (https://github.com/linux-wmt/linux-vtwm/wiki/Boot-from-sd-card). The script will then be executed.
Usually u-boot will look for keyboard input on the UART, but you can get it to use the display and keyboard of the netbook, or download something from the network, or boot Linux from the SD card.
From there you should be able to access the Android partition and see if you can do something with it.

The other option is locating the TTL UART pins or pads on your motherboard, and connect a TTL serial adapter to it. There you can see logs from Android booting, and maybe reach a shell.

--
Adrien.

Thanks Adrien.

Will look into that route over the weekend with more time. Thanks for your reply!.

PS: While I have the PCB laid bare on the table, I really would like to find if there s any surgical way of getting a serial console out of this thing... that's why I asked if there were other PC789 owners who may have gone that route.

The 4 solder pads labelled GND, D+ D- VCC look enticing. (Like I said, those don't seem like USB as they should be GND D- D+ VCC (D+ and D- are reversed on the silkscreening).

For a picture I took see
https://pbs.twimg.com/media/CuH9bPtXEAAZvdt.jpg

FC

[Alexey Charkov]

Hi Fernando,

2016-10-07 10:13 GMT+03:00 Fernando Cassia <fca...@gmail.com>:
> I have read many messages from this group, and I think this is the right
> place to ask, you have the programmers, and you have the guys with hardware
> knowledge like Alexey.
> Hardware: HL PC789 R1.0 netbook It features a WM8880, 1Gig of RAM and 8GB
> Toshiba NAND for storage, shipped with Adroid Kitkat.

All of those beasts I encountered also have an SPI serial flash chip
which holds the primary bootloader (W-load, non-interactive, can only
access serial flash), secondary bootloader (U-boot, interactive over
serial console, can access serial flash, NAND, SD, sometimes Ethernet
and/or USB), as well as two copies of u-boot config with a checksum.

> To add insult to injury, there is no way to invoke the android repair menu
> as phones depend on one pressing power on + volume updown and there are no
> such keys on these netbooks (and believe me, I have tried every possible
> combination).

Sure, as there is no recovery image in those ;-)

> So here I am with a WM8880 device that boots with an animated logo until the
> point it ends with a black screen and ... nothing.

Then it's not too bad in fact. If you see the first static logo, then
your U-boot works. If you see the animated logo, then your kernel
starts up, too. So your SPI and NAND are apparently ok - the problem
is somewhere down the road.

> I ve tried installing ADB/Fastboot on a Win7 system and plugging the netbook
> with a USB male-male cable to no avail. ADB doesn t see any android device.

There is USB device (OTG) functionality in the chip, where ADB might
work. Though I haven't seen a device with a connector soldered in
place, except developer boards such as APC (only heard reports of
such).

> So by looking at the PCB I saw what looks like an unsoldered PCB header,
> with the only diffeerence that the D+ and D- pins are reversed. In other
> words, D- is next to VCC and D+ is next to GND which doesn't make sense for
> USB.

Could be an OTG port instead. Serial is most usually unmarked (and
would say Rx+Tx instead of D+ and D-, as it doesn't have anything to
do with differential signalling).

> I wonder if this is some sort of RS232 port? or SPI?

There is most likely a serial port somewhere on the board as
unsoldered unlabeled pads, but keep in mind that WM8880 seems to use
CMOS signalling, so you will need a USB to serial converter such as
FTDI to get access (my old PL2303 didn't work).

> I'm also curious if there's any affordable hardware interface allowing one
> to program the NAND storage "in place" just by affiing a reader/writer
> directly to the chip pins, without powering the whole board. Just thinking
> aloud, pershps there's an easier option.

Sounds like an overkill, and frankly I don't know any :) You can
reflash the SPI chip with relative ease if required though (either
through a proper programmer for ~60 bucks with free shipping from
China, or through something home-brew such as Arduino).

> In other words... WHAT WOULD ALEXEY DO? ;)

It's always best to get serial console access as the first step when
something fails in weird ways, as it's quite annoying to wander in the
dark.

Adrien's advice to try booting from SD is also an option, but your
problem might be related to e.g. WonderMedia's obscure u-boot
configuration variables which their stock kernel reads as a poor-man's
substitute for a proper device tree to know how to work with the
specific board. You'll never know without seeing how it fails.

Also note that I haven't yet figured out how to make WM8880 work using
an upstream kernel without crashes in USB code, but quite frankly the
last time I tried was probably two years ago (had zero time for this
stuff since then unfortunately).

Happy to help further if I can!

Cheers,
Alexey

[chunw...@gmail.com]

Hi Fernando,

The data on NAND flash is probably damaged, and that is why you cannot boot into Android. The data on SPI flash is fine, so u-boot logo is fine.

When the battery level is critical low, WM8880 will wake up itself and boot into a special recovery mode. If the power was lost during the recovery process, the NAND ECC data in memory get lost and the data on NAND flash get damaged.

This is a common HW bug on WM8880 tablets and some netbook. And the solution is quite easy by using a SD card. Find the firmware for your WM8880 device, copy it to SD card, then boot from it. You should be able to see display of firmware installation. After the installation is done, your device will back to life.

If you place your WM8880 device with battery drained for a long time, maybe several months, then it is very likely your device won't boot into Android, and need re-install firmware again.

Don't install firmware not belong to your device model, otherwise you could install wrong hw settings on SPI flash, and your device won't boot again and becomes harder to fix.


Fernando Cassia於 2016年10月7日星期五 UTC+8下午3時13分01秒寫道：

[tonyli...@gmail.com]

i have https://www.ebay.com/itm/1088A-Android-4-4-Notebook-10-1-Laptop-WSVGA-WM8880-1GB-8GB-WIFI-Camera-NEW/152690143487?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

i have same problem as op where can i get the firmwear for it Please