"Pinebook Serial Console" unreliable, inhibits boot, kills WiFi and SD
#1
I purchased a "Pinebook Serial Console" from the Pine Store to use to debug my Pinebook Pro's boot process. It seems to work fine on the USB side, but on the Pinebook side it's got some serious issues.

1. If I try to boot the machine with the cable plugged in, uboot does its thing, says it's starting the kernel, and then nothing ever happens again. No serial output, no video, no network presence. (If I yank the cable, right after making a selection, before it finishes loading the kernel, everything boots fine from there, and I can plug it in after boot completion and hit enter for a login prompt.)
2. If I plug it into a running "default Debian+MATE" system, I get errors on the kernel log about SDIO screwing up, and WiFi dies. (If said system is booted from an SD card, it also loses communication with the card and does what any Linux system does when you yank its root filesystem away.)
3. If I leave the cable plugged in during a reboot (not a cold boot), uboot fails to read the SD card and hangs—with or without an SD card plugged in.
4. Even when things are otherwise working, the connection is very unreliable. If the PBP outputs too quickly, vast quantities of output are dropped. This happens both in Linux and uboot. If I do an ifconfig, for example, I get the first line and a half or so okay, followed by mangled snippets of the remainder. And nmtui is completely unusable.

The wiki does mention that some of these cables render the PBP unbootable, but I didn't see any previous mention of this on the forums. I assume that previous discussion of this problem has happened in other media.


First messages from the kernel log after WiFi dies an untimely death:


Code:
Dec  5 08:31:58 Debian-Desktop kernel: [  266.315561] sdioh_buffer_tofrom_bus: R
X FAILED ffffffc0f1ed5a20, addr=0x08000, pkt_len=32, ERR=-84
Dec  5 08:31:58 Debian-Desktop kernel: [  266.315585] dhdsdio_readframes: RXHEAD
ER FAILED: -35
Dec  5 08:31:58 Debian-Desktop kernel: [  266.315600] dhdsdio_rxfail: abort comm
and, terminate frame, send NAK
Dec  5 08:31:58 Debian-Desktop kernel: [  266.339116] dwmmc_rockchip fe310000.dw
mmc: All phases work, using default phase 0.


That repeats a few times, then I see escalating stuff about WiFi crashing and burning.

This cable is still useful for basic boot troubleshooting (of the "did my kernel boot at all?" variety), but something is clearly very, very wrong.
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#2
(12-05-2019, 03:06 AM)Solra Bizna Wrote: The wiki does mention that some of these cables render the PBP unbootable, but I didn't see any previous mention of this on the forums. I assume that previous discussion of this problem has happened in other media.

<snip>

This cable is still useful for basic boot troubleshooting (of the "did my kernel boot at all?" variety), but something is clearly very, very wrong.

This sounds exactly like my experience with the official pine64 cable. It has been discussed on the forum but not for some time (so don't worry). If you are interested one of the older threads is here: https://forum.pine64.org/showthread.php?tid=7746

I'm afraid I gave up completely on the official cable and soldered together a cable to connect one of my existing UART adapters to the PBP. This works fine and enabled me to do plenty of interesting hacking. Having said that I'm still a bit disappointed that the official cable is non-functional for so many people.

Actually thanks for reminding me about this...

I had a theory about what might be going wrong but it seemed so unbelievable that I didn't check it out. However given I still can't think of any other way for an UART adapter that is sending no characters to crash the Pinebook I broke out my multimeter.

It looks like I was right... although I'd be grateful if someone else can confirm it since I'm still rather in shock...

The official adapter is using 5v TTL logic when it should be using 3.3v TTL logic. In other words it appears to be over-volting the UART circuit on the board and causes enough electrical havoc to (eventually) crash the machine.

My advice would be to IMMEDIATELY STOP USING YOUR ADAPTER FOR ANY PURPOSE until you have measured the voltage between the middle two rings on the adapter.

(sorry for shouting but there is a risk of damage from this sort of thing).
PineTime: wasp-os and MicroPython, Pinebook Pro:  Debian Bullseye
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#3
(12-05-2019, 04:07 AM)danielt Wrote:
(12-05-2019, 03:06 AM)Solra Bizna Wrote: The wiki does mention that some of these cables render the PBP unbootable, but I didn't see any previous mention of this on the forums. I assume that previous discussion of this problem has happened in other media.

<snip>

This cable is still useful for basic boot troubleshooting (of the "did my kernel boot at all?" variety), but something is clearly very, very wrong.

This sounds exactly like my experience with the official pine64 cable. It has been discussed on the forum but not for some time (so don't worry). If you are interested one of the older threads is here: https://forum.pine64.org/showthread.php?tid=7746

I'm afraid I gave up completely on the official cable and soldered together a cable to connect one of my existing UART adapters to the PBP. This works fine and enabled me to do plenty of interesting hacking. Having said that I'm still a bit disappointed that the official cable is non-functional for so many people.

Actually thanks for reminding me about this...

I had a theory about what might be going wrong but it seemed so unbelievable that I didn't check it out. However given I still can't think of any other way for an UART adapter that is sending no characters to crash the Pinebook I broke out my multimeter.

It looks like I was right... although I'd be grateful if someone else can confirm it since I'm still rather in shock...

The official adapter is using 5v TTL logic when it should be using 3.3v TTL logic. In other words it appears to be over-volting the UART circuit on the board and causes enough electrical havoc to (eventually) crash the machine.

My advice would be to IMMEDIATELY STOP USING YOUR ADAPTER FOR ANY PURPOSE until you have measured the voltage between the middle two rings on the adapter.

(sorry for shouting but there is a risk of damage from this sort of thing).

I have the original serial console cable for the Pinebook (1080p) and, in response to an earlier query about serial interface, I measured my own quiescent voltages on the 3.5mm 4-pole jack it was terminated in ... and yes it was 5v.

Not sure if there was any internal impedance that might reduce the final voltage to the Pinebook when "under load" but it did seem odd.

(never actually used the cable with my Pinebook 1080p or with the Pinebook Pro - the latter because it required the case to be opened and the terminal/sound switch toggled - I'd rather not break anything just now)
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#4
(12-05-2019, 08:35 AM)neilman Wrote: I have the original serial console cable for the Pinebook (1080p) and, in response to an earlier query about serial interface, I measured my own quiescent voltages on the 3.5mm 4-pole jack it was terminated in ... and yes it was 5v.

Not sure if there was any internal impedance that might reduce the final voltage to the Pinebook when "under load"

If the input impedance was that low, it would not work.

Do any of the Pine computers use 5V for UART serial console?
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#5
Holy cow. I just checked the quiescent voltage on mine and... 5.025V. Guess I'll be tearing that cable apart to make one of my own... O_O

Are all of these cables 5V, or are some of them 3.3V? And I second zaius's question...
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#6
Thanks danielt, I was trying to use nvme and had the serial console hooked up so I could mess with uboot, but kept having random panics and problems.  Disconnected the serial console, and so far so good on the nvme front.
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#7
(12-05-2019, 11:59 AM)zaius Wrote: Do any of the Pine computers use 5V for UART serial console?

I'm pretty new in this neighbourhood (I only got sucked in after meeting @Luke at FOSDEM 2019) but I don't think so. The other UART adapter in the Pine store is multi-voltage but is always photographed configured in 3v3 mode.
PineTime: wasp-os and MicroPython, Pinebook Pro:  Debian Bullseye
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#8
(12-06-2019, 04:07 AM)danielt Wrote:
(12-05-2019, 11:59 AM)zaius Wrote: Do any of the Pine computers use 5V for UART serial console?

I'm pretty new in this neighbourhood (I only got sucked in after meeting @Luke at FOSDEM 2019) but I don't think so. The other UART adapter in the Pine store is multi-voltage but is always photographed configured in 3v3 mode.

There is also this post:

https://forum.pine64.org/showthread.php?...0#pid53150

Pine sells these little boards:
https://store.pine64.org/?product=padi-serial-console
https://store.pine64.org/?product=pine64...programmer

but only one cable:
https://store.pine64.org/?product=pinebo...al-console

If that cable is 5V as reported, and xalius is correct, then Pine should stop selling it for use with the Pinebook and PBP.

There is also this issue here:
https://nixos.wiki/wiki/NixOS_on_ARM/PIN...al_console

So it is possibly it is both the wrong voltage, and the wrong chipset.
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#9
(12-06-2019, 01:49 PM)zaius Wrote:
(12-06-2019, 04:07 AM)danielt Wrote:
(12-05-2019, 11:59 AM)zaius Wrote: Do any of the Pine computers use 5V for UART serial console?

I'm pretty new in this neighbourhood (I only got sucked in after meeting @Luke at FOSDEM 2019) but I don't think so. The other UART adapter in the Pine store is multi-voltage but is always photographed configured in 3v3 mode.

There is also this post:

https://forum.pine64.org/showthread.php?...0#pid53150

Pine sells these little boards:
https://store.pine64.org/?product=padi-serial-console
https://store.pine64.org/?product=pine64...programmer

but only one cable:
https://store.pine64.org/?product=pinebo...al-console

If that cable is 5V as reported, and xalius is correct, then Pine should stop selling it for use with the Pinebook and PBP.

There is also this issue here:
https://nixos.wiki/wiki/NixOS_on_ARM/PIN...al_console

So it is possibly it is both the wrong voltage, and the wrong chipset.

To provide some additional information about the genuine Pinebook console adapter I purchased from the Pine store I pried off the covers from the USB plug end...

Chip used is a CH340G on the underside with passive components and just a 12MHz crystal on the top side
There is no 3v/5v selection capability - only the connection holes for the wires.
There are five solder holes opposite the USB plug
It uses a 900mm-long four-core signal cable...

  Red wire to 5v connection (snipped off inside the jack plug end)
  White wire to RxD connection
  Green wire to TxD connection
  Black wire to GND connection
  no wire to 3v connection

As stated I measured 5v on the TXD and RXD connections at the 3.5mm 4-pole plug end.

Never "used in anger" - could it have killed or damaged the Pinebook and possibly the Pinebook Pro if I had tried to use it?
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#10
Cracked mine open, too. CH340G. No obvious way to select 5V/3.3V. Six solder pads:

Red wire to 5V (not connected on plug, guess it's snipped at that end like neilman says)
Black wire to GND
White wire to RXD
Green wire to TXD
No wire to CTS
No wire to RTS

(12-06-2019, 02:42 PM)neilman Wrote: Never "used in anger" - could it have killed or damaged the Pinebook and possibly the Pinebook Pro if I had tried to use it?

Absolutely yes.

ETA: the wires for RX and TX were almost twisted together inside the case. Same with GND and 5V. They would have shorted together at the drop of a hat.
ETA2: Apparently the CH340G does support 3.3V operation, but it needs 3.3V power to do it, so there won't be any easy modification of this cable...
  Reply


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