November 2006 Archives

Serial hack

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Last entry I wrote a bit about having to improvise a serial connection. Here are the details on what I did to get this working. As I mentioned, I happened to have a spare Keyspan USB Twin Serial adapter, a USB to Mac DIN-8 serial adapter left over from a past project. The big fuss with adding a serial port to a Linksys (or similar) router is that most such devices have an RS-232-ish connection available internally, but the voltages aren't at the proper levels (generally 3v instead of 12), and a bit of circuitry is needed to boost these levels to something compatible with most RS-232 gear. I was able to bypass those issues using this adapter, as I'll explain below.

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Bricked... and fixed

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Thanks to some firmware changes gone wrong, my router became unresponsive, and wouldn't even properly boot. I wasn't even able to get the failsafe mode working. I had planned on eventually adding a serial port to the router, but hadn't done so yet, and wanted to get it up and running asap.

Digging up an old Keyspan USB-Serial adapter, I stripped an old phone cable and soldered the wires directly to the pads for the (missing) RS-232 connection on the router, and soldered the other ends to appropriate pins on one of the chips in the Keyspan adapter, and (much to my surprise) started getting serial output. I'll post pics and some additional details in a future entry.

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This page is an archive of entries from November 2006 listed from newest to oldest.

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