I got OpenWRT working on a ZBT-CPE2801

However, I am not setup to compile and build
I have done so, long time ago, but it would take quite a bit of time and effort to get back into it.

Anyone who wants to do the build, based on my findings?

Basically, I took the CPE2801, discovered it reported in the UBoot serial console as "board: MT7628AN reference design", so I loaded the OpenWRT "mediatek_mt7628an-eval-board"

The only thing wrong was:

  • Reported itself under the wrong name
  • Only has 4MB flash instead of 16MB
  • LAN/WAN ports swapped
  • LED's needed to be fixed

Everything else seemed to work. One does need to load Luci and all the modem drivers manually, the reference build is very empty, but it is a quite useable way to kickstart the CPE2801 on a modern OpenWRT

Next I found the OpenWRT for "unielec_u7628-01-16m", which I suspect is also pretty much a "MT7628AN reference design" but with 16M flash, so I loaded that, and now everything worked, but with the correct 16MB flash

For me, it means I can go forward, so I am not very much stuck, but maybe someone can do a proper build. I will post the LED and ETH and modem details here later anyway.

Careful 16Mbits flash is 4MBytes
You need to submit a PR if it turned out 16MBytes. What does uboot report about flash?

a slight miscalculation there :wink:

Thanks. Mind you, 16Mbit is not 4, but 2 Mbyte
Anyway, it is 16Mbyte. Not onlu UBoot, but also I observed the actual Winbond 25Q128 chip on the board.

1 Like

That generally doesn't mean anything (at least almost nothing). Vendors typically start with the provided chipset SDK and their modified reference designs. As serial console access is usually not user facing, they don't tend to adapt the board names even though the hardware might be substantially different from the eval boards the code once was based upon.

Ergo: you still need to come up with a bespoke image (DTS, OEM flashing instructions, sysupgrade support etc.) for your device. The eval board recipes are wrong and are potentially actively harmful to your device (ranging from wrong flash information/ partitioning, overwriting crucial calibration data, MAC addresses and similar or even physically damaging the hardware via wrong pinstrapping or clock settings).

This is true. Even the original OpenWRT was based on Linksys publishing the sources for their WRT54G. While this is true, both in origin and in a perfect world, I have to wonder ...

How many of the all the OpenWRT devices are so correct that they were build of the official design sources, ensuring each and every internal pull-up resistor is correct. Versus how many were just hacked together by guessing how it was build.

Anyway, we just have to hope they were as efficient as possible, and changed as little as they could get away with. Also, we do have the official LEDE build. Is there anyway to extract the menuconfig file from that? Or extract the chip config routine. I use to be a bit deeper into Freetz (the OpenWRT similar project for AVM Fritz), and the menuconfig file was often in the builds.

Mind you, this is a niche device, no-one will put in any decent time, and rightly so. So for now though, it seems to work. Quite well even, though I am struggling a bit with the APN auto discovery.