Solder but no wiser#

Wed, 13 Jun 2018 07:17:21 +0000

Everyone should have at least one hobby that they're no good at and/or dislike doing.

For me that was once playing guitar (still have the instrument, no longer have the calluses) but these days it's soldering. So after having stuck three short pieces of paperclip into adjacent holes inside my Trendnet TEW712BR and showered them with blobs of molten tin, I was as surprised as anybody when I plugged my USB TTL serial converter in and found I had a root console.

Notes for others who may follow this way:

• there are four screws in the base of the unit that need removing: two that you can see and two hidden under the stick-on rubber feet.
• My serial connector had no indication on it to say which wire was which. The image quality is not the best, but you may be able to make out that from back to front I've connected green (Rx, unless it is Tx), white (Tx - if it's not Rx) and black (Gnd). Red is V+ and doesn't need to be attached to anything.
• if the converter doesn't work and keeps reporting pl2303 ttyUSB1: pl2303 converter now disconnected in dmesg over and over again, the workaround may be to unplug your wife's old Galaxy S5 phone from the other USB port. I honestly have no idea what was going on here, but I found a standalone charger for it, so it will be fully charged again by the time small boy wants to use it for his Pokemon.

It turns out I'm slightly ahead of myself in doing this right now, because although I have an image for Milestone 1 that runs on an Arduino Yun, it's too big - there is only 4MB flash in this little box. Still, at least I am able to capture a boot log and find out its partition scheme and kernel load address.

Yes, I have working wifi, and the use case for "WiFi access point/range extender" (WiFi in AP mode via hostapd, bridged to Ethernet, and a DHCP client). This entailed

• restoring the bitrotten support for ar71xx (needed to add config options for the kernel entry point and location of some OpenWRT patch sets)
• writing a hostapd module
• adding support for bridges in the code that reads configuration.interfaces

Mostly fairly straightforward stuff so far - or at least, at a remove of anything up to two weeks since I did some of this work, I've forgotten whatever problems I ran into. It's all in wap.nix , which still copies a bit too much code from backuphost.nix but that will change as soon as I can get my head around fixpoints. To get it to fit into flash on the device I'm going to need a smaller kernel and perhaps a smaller busybox.