HP-48GX DIY infrared to serial converter

[pito]

Hi, looking for a hint/link on a DIY infra to serial converter project (bidirectional - TX and RX) somebody wants to share?
Thanks!

[Jeff_Birt]

(01-15-2024 12:00 PM)pito Wrote:  Hi, looking for a hint/link on a DIY infra to serial converter project (bidirectional - TX and RX) somebody wants to share?
Thanks!

Why do that when it already has a hardware serial port?

[gege]

Hello,

Some information about HP48 interface (with IR circuit).
A receiver (only) for IR with an Arduino.

[MeindertKuipers]

(01-15-2024 03:04 PM)gege Wrote:  A receiver (only) for IR with an Arduino.

Very much recommended. And there is a possibility to control the sending LED as well with some Arduino coding

[pito]

Thanks for the hints!
Why I want the infra - my 48gx is in perfect condition and I do not want to risk a damage while messing with hw serial (as the calculator is almost not repairable).. And yes, I made myself the hw serial long time back, it worked fine.

PS: here is an another receiver only for a printer. Also there is a discussion on the IR receiver chip as well..

[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

[pito]

Ralf thanks! Yup, I did with the hw serial too, but I thought there will be something one may build off his/her junkbox. Like a small pic12F1572 with an IR Rx demodulating @38kHz and an IR Led (plus an USB to serial dongle).. The critical part is the Rx chip, I have various ones here, not sure those are fast enough..