HH5a UART interface

[Sailer]

I think I've found an UART interface of BT Home Hub 5a.

TXD - The point right of R77
RXD - The point right of R78
Boot_Sel2 - Top of R45
They are located just below the NAND chip.

bitrate: 115200

Output on start:

Code: Select all

ROM VER: 1.1.4
CFG 06
NAND
NAND Read OK

DDR autotuning Rev 0.3d
DDR size from 0xa0000000 - 0xa7ffffff
DDR check ok... start booting...

Unfortunately no any "Hit any key to stop" like on HH3a

Pinout of VRX268:
TXD - B22
RXD - C23

[darklight]

Thank you very much for these

Do you also know the locations of the 3 BOOT_SEL pins?
Those would allow booting (a custom version of) u-boot via UART.
-> found a solution myself in Booting via UART

See: https://github.com/torvalds/linux/blob/ ... _soc.h#L52 and http://wiki.openwrt.org/toh/arcadyan/arv752dpw#uart (the steps can be used for any lantiq danube/VR9 device - given you have the right ".asc" file for your board).

[dabbler]

Is there an alternate point for BOOT_SEL2 please? I dropped my PCB and the pad got ripped off. Hope there is any some one can help me? Thanks!

[bill]

Perhaps you could solder a temporary wire to GND and then touch the other end of the wire to the top of R45 resistor when you need to short Boot_sel2 to GND.

Once you have flashed LEDE onto the HH5a and unlocked the bootloader, you don't need to use the Boot_Sel2 any more.

[Coarist]

Thanks for sharing. It really helps.