BT Home Hub 5 refusing input when common ground connected

After following a tutorial, I got to the uboot interface on my BT Home Hub 5 type A, there was a countdown that I waited through and then when I used the tftpboot0x81000000 lede-lantiq-xrx200-BTHOMEHUBV5A-installimage.bin; bootm 0x81000000 command I encountered an error wrong image for bootm command. Unfortunately I accidentally unplugged the hub and now when I connect the common ground for serial I cannot seem to send any data through serial, although recieving works perfectly. I can still get to the UART boot screen but I can't do anything after that as I can't send the lede-lantiq-bthomehubv5a_ram-u-boot.asc data to get to the next stage. Also the default router os no longer boots and the manual reset button doesn't do anything.

Is router stuck at dreaded CFG 04 UART prompt when you turn on the router normally?


There is warning about this in section 7.3 of the full installation guide, and in the shorter Windows guide you referenced. It is believed to be caused by shorting 'bsel_2' pin to 'Ground' for far too long, causing electrical component failure. The HH5a is toast if that is the case....

Sorry, I had forgotten about this post until recently.
No, the router isn't stuck in the UART prompt, it boots as regular when the bsel_2 pin isn't shorted.

Also I've only just remembered to say but I'm sure the TTL Serial to USB cable I have is working normally as I've tested with two cables and even pulled out an old Raspberry PI 3 B+ to make sure.

if hh5a boots normally, and the wiring between the Pi/serial adapter to the HH5a are good, including the Ground-to-Ground connection, then it is likely the RX on HH5a serial interface is perhaps damaged and no longer accepting any input. There is no fix, unless another reader has any suggestions.

What voltage does your TTL serial cable use, 3.3v or 5v? I think the bt hub uses 3.3v, so a serial adaptor with a 5v tx line might damage it.

I would check the soldering on the rx pad is good.

The wiring seems fine as the connection doesn't seem to break at any point.

I doubt the RX damaged as it was working fine prior to powering the device off in the Uboot interface and I seem to get some garbled junk echoed back when I type if the ground isn't connected and it works fine when the device is powered off with/without ground.

The TTL serial cable uses 3.3v as far as I know, the one I used was some cheap Prolific PL2303 clone that I've had lying around for a while and the soldering seems solid.

ive recently flashed 3 of these using a Prolific cable, outputs 3.3v between TX & GND easy way to test your cable it connect the cable TX & RX together and anything you type will show up in your putty terminal like a text editor, rules out cable fault, my firs flash attempt was so bad i destroyed the pads & had to use the resistors before the pads for tx & rx & ensure you connect the cable ground to a ground point on the board before you try and boot, sure i was getting garbled data connecting GND after powering the boaard (I used a pad above the DSL port labeled "CN5" The top pad of this connector is connected to the ground plane, use a separate wire (i also used a metal compass on one) to short boot select separately, Yellow used as GND to cable GND & Black as bootselect to GND point on he board, shorted to metal WPS button casing for 1ish second

Re reading see you power cycled between the prepare command & flashing the image, may have left it in a wiped state, cant say for sure, if you can get input then may need to restore you backup but this requires sucsessful connection

The TX & RX pads on the hub connection seems fine as when powered off and the serial cable is connected anything typed will be echoed back, although I do have to use the resistor to switch to UART mode due to me messing up the pad.

Normal boot: (doesn't get past this)

When UART is grounded:

Nothing that I type is echoed back or responed to once I get to either normal boot or UART mode and it doesn't get past the "start booting..." stage so I suppose it may be wiped?

How would I restore a backup?

and the hub dosnt boot into sock FW, if i remember i think output via serial stopped at one point during stock boot, what state is the LED lights in? staying green flashing? or if left will it switch to a blue or red with broadband light?

after turning the hub on and waiting through the solid green it starts flashing green and then goes to a solid blue and then after waiting a little more it switches to a solid orange with the broadband light flashing.

No extra info through serial though.

ok so this is a good sign, its still booting into the stock BT firmware, and reporting no DSL connection, and i think its normal for the stock firmware to stop serial once it exits bootloader & starts loading the stock firmware, to confirm, you have the cable permanently connected to a ground point, & a separate connection to temporarily bridge (about 1 second) the boot select line to any ground point on the board while power on, you should be able to paste the code in again (lede-lantiq-bthomehubv5a_ram-u-boot.asc) & try flashing the image again (lede-lantiq-xrx200-BTHOMEHUBV5A-installimage.bin), if i remember there was a warning about not running the bootloader unlock/decrypt command again, don't know what the result of doing this part again would be so be aware, also you are getting a reading out but you dont get a response whan you paste in the code? maybe the connection for RX (Board) and TX (Cable) is iffy as the output can still be received without input connected :slight_smile: