HP-48GX DIY infrared to serial converter

[Hiwi]

Hi pito,
i made a lot of serial stuff of diy sensors, compass devices, interfacess, controllers etc for my HP48
in the last 20 years and had never a problem with the serial port.

You can use opto couplers connected to your serial port or in the circuit instead of a direct connection, but it is not really neccessary.

I have built some of the converters as mentioned in this thread. The software is free (Thanks to Martin Hepperle) and easy to maintain. It has a debug mode, so you can test the connection in both directions with a simple terminal app (Pressing "T" invokes the transparent mode)
However i like this litte box and use it for my HP48/28 with Christoph Gießelink's ir printer emulation as you can see:

   
   

You can print programs and safe them on a PC, which is for the HP28 essential.

Ralf