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ijabbott · (This post was last modified: 11-07-2018 08:50 PM by ijabbott.)

(11-07-2018 03:54 PM)Craig Bladow Wrote:
(11-07-2018 08:41 AM)ijabbott Wrote: I just use an FTDI TTL-232R-3V3, a couple of 1K resistors, and a steady hand!

Can you point me to a schematic for your cable?

I think I actually used the "RPi debug" variant of the cable (TTL-232R-RPi) which has three wires terminated in single-pin DuPont style connectors. (There are other variants of the cable with more wires for RTS/CTS, and different connector options (including bare wire ends). Just make sure you get a 3V3 (3.3V) cable and not a 5V one). I just poked the 1K resistors and a ground wire into the three DuPont connectors.

On the RPi cable TXD is orange, RXD is yellow, and ground is black. You can follow the instructions as written for a different FTDI board here: http://www.hpmuseum.org/forum/thread-2719.html, but you will need to supply the 3V power for the calculator from batteries or a bench power supply, because this cable does not supply power.