Having started to add some Zigbee devices to the home automation mix, I have a version of one of the "standard" Tuya ethernet gateway models. This same board appears in devices from all sorts of companies.

Router

The reverse side is well marked with many test pads visible.

A quick web search revealed people had done the hard work already, especially Paul Banks https://paulbanks.org/projects/lidl-zigbee/.

Serial Connection

I found a USB-Serial dongle and connected GND, RX & TX pins on both the dongle and board. With everything configured and minicom configured (38400, 8N1) I hit enter...

tuya-linux login:

It looks like the serial connection is working 😄

Of course, now I need to gain access to the bootloader. Paul suggests hitting ESC when the boot starts, so after checking that the ESC key generated output via minicom, I power cycled the device.

Booting...

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@
@ chip__no chip__id mfr___id dev___id cap___id size_sft dev_size chipSize
@ 0000000h 0c84018h 00000c8h 0000040h 0000018h 0000000h 0000018h 1000000h
@ blk_size blk__cnt sec_size sec__cnt pageSize page_cnt chip_clk chipName
@ 0010000h 0000100h 0001000h 0001000h 0000100h 0000010h 000004eh GD25Q128
@ 
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
DDR1:32MB
 
---RealTek(RTL8196E)at 2022.03.29-15:59+0800 v3.4T-pre2 [16bit](380MHz)
P0phymode=01, embedded phy
check_image_header  return_addr:05010000 bank_offset:00000000
no sys signature at 00010000!
get uboot flag failed
Jump to image start=0x80c00000...
decompressing kernel:
Uncompressing Linux... done, booting the kernel.
done decompressing kernel.
start address: 0x80003780
Linux version 3.10.90 (wsj@LAPTOP-MO8FQJRA) (gcc version 4.6.4 (Realtek RSDK-4.6.4 Build 2080) ) #8 Tue Mar 292
CPU revision is: 0000cd01

Despite a number of attempts, I was unable to gain access to the bootloader. Looking at this online discussion it appears to be a common issue. The minicom output doesn't show the expected character ( ^[ ), which may point to the issue 😦

Having tried using MacOS and Ubuntu and with different connecting cables, I still had no joy. The USB dongle uses a CH340G chipset which seems to have trouble. If anyone has suggestions to cure this, then I'd love to hear them.

I've ordered an FTDI dongle as most people seem to have success with those.