HP Calc with good IR transmitter

[matalog]

Which of the HP calculators would I be best to get if I want it to be as cheap as possible but having a decent IR comms port? I say decent, as the HP 50g's IR wasn't as good as others.

[brouhaha]

(03-27-2023 09:07 PM)matalog Wrote:  Which of the HP calculators would I be best to get if I want it to be as cheap as possible but having a decent IR comms port? I say decent, as the HP 50g's IR wasn't as good as others.

Decent for what? Probably none of them.

All of them are deliberately designed to have very short range. They're intended for use with an 82240 printer up close, or a second calculator up close and directly head-to-head.

[Allen]

(03-27-2023 09:07 PM)matalog Wrote:  ...as cheap as possible but having a decent IR comms port?...

I think the cheapest IR port available is likely the 17BII (original gold bezel from the 1990s and early 2000s). Average strike price now with shipping is usually under $25 USD. (post covid inflation adjusted numbers). Can't do much with it other than print.

The HP 48G/G+/GX has the ability to control the IR output with a little more fidelity. I used to turn on (and off) the CRT TV in a high school class room at a rage of ~7m using my HP 48G and the brilliant Remote program. The teacher thought the TV was broken because it would only ring from the CRT and never actually display anything.

If I recall correctly, only the receiver element was handicapped to prevent cheating on tests.. the transmitter seemed to function at a decent range, depending on what you were doing.

[matalog]

I don't mind too much about the range, I could work 5or 10 cm away from receiver for the project I am working on.

I just need to have control of the IR LED, to modulate it once every 3 milliseconds, say.

Could I do that with a 50g?

[Allen]

(03-27-2023 10:03 PM)matalog Wrote:  Could I do that with a 50g?

If you want to reverse engineer Bjorn's code and port it in assembly language to a new platform? Maybe?

Much depends on the gain (optical, coding and otherwise, along with error correction) at the RX end, along with considerations for ambient noise you may want to consider (sunlight for example?) and free space pathloss, etc..

Calculating range for communications systems often involves an estimated link budget, not just transmitter specifications.

[brouhaha]

(03-27-2023 10:03 PM)matalog Wrote:  I just need to have control of the IR LED, to modulate it once every 3 milliseconds, say.
Could I do that with a 50g?

That might be workable, but note that your software modulation will essentially be on-off keying (OOK) of a 32.768 kHz carrier, or an IRDA serial stream. The 48 did that in hardware; in the 49 and 50 it might be hardware, ARM code, or some combination of both, as part of the ARM code "operating system" of those models.

How precise does your 3ms interval need to be? It's difficult to get precision timing on the 49 and 50.

Allen mentioned the original 17BII. That uses Saturn, and the hardware can only do OOK of the 32.768 kHz carrier. To use that for your own OOK modulation, you'd have to write Saturn assembly, and poke it in and execute it via the memory viewer. The 28S might be better as you can call Saturn assembly from user RPL, like the 48/49/50.

If you're willing to write ARM assembly (or C compiled to ARM code), it's possible that the Swissmicros DM-42 might be able to do what you need, but it isn't cheap.

[matalog]

The timing can use anything between 2 and 4 milliseconds delay between each modulation.

I have a 49 and a 50g, which would be better?

[brouhaha]

(03-28-2023 06:49 AM)matalog Wrote:  I have a 49 and a 50g, which would be better?

I don't think there would be much difference.

[striegel]

The clamshell palmtop model HP 95LX is provided with a robust infrared transmitter. In the past, I had a free program for using this device as a TV remote control and it worked from across a 20 foot room.

Follow-on models (100LX and 200LX) changed to a considerably lower power IR transmitter, although those models could also operate serially at considerably higher speeds.

[John Garza (3665)]

Just curious...
Why the requirement to use a calculator?

-J

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