Now that the HP82240B is long gone, compatible printers are still available new, manufactured by Martel Instruments of England. At martelinstruments.com, check out the MCP8850 and MCP9850 which are versions built to the HP Ir calculator interface. These calculators are available at a US distributor at 800-578-9021 (Current Components Incorporated) for about $170. The print speed and clarity is supposed to exceed that of the old HP printers. Martel also makes versions of these printers with multiple interfaces built in and with different power supply options, but I have not yet found a US distributor of such (MCP8830's). But here's my question: Wouldn't it be nice to use the HP Ir calcultor output to send data directly to a PC? Has anyone done this? Is the little HP Ir to RS232 adapter by Aegis (IR-HP5) for about $40 the answer? All this was probably covered by previous questions and answers here or in those old user groups (or is that groups of old users?), but I thought I would ask again because this forum is such a great brain trust. Any observations on HP Ir issues would be appreciated, especially on an HP41 with the Ir module. I see one site discusses building an Ir receiver linked to a parallel port error line using cheap Radio Shack parts, but I wonder if someone knows of a stock PC Ir receiver for either USB or serial that can take in data from an HP calculator Ir transmitter. Thanks.
Ir ... I have an HP Ir question ...
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06-03-2003, 01:38 PM
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06-04-2003, 02:11 AM
Ok, I see them, at If anyone tries one of these, please do report on your experience.
Yes, I've heard of using the IR to transmit/receive to/from a PC. I've
I don't know about the other calculators, but on the 48G series, if you
More information on the 82240A/B Red Eye encoding can be found at
Regards,
06-04-2003, 01:45 PM
> But here's my question: Wouldn't it be nice to use the HP Ir calcultor output to send data directly to a PC? Has anyone done this? The protocol information is available at http://www.hpcalc.org/details.php?id=4742. > Is the little HP Ir to RS232 adapter by Aegis (IR-HP5) for about $40 the answer? No it isn't, the IR-HP5 is a "normal" IR to wire converter for the normal RS232C protocol. Reason, the product is advertised with max. 57600 baud, the HP Red Eye printer protocol has a fixed baudrate somewhere around 600 baud. > All this was probably covered by previous questions and answers here or in those old user groups (or is that groups of old users?), but I thought I would ask again because this forum is such a great brain trust. Any observations on HP Ir issues would be appreciated, especially on an HP41 with the Ir module. I see one site discusses building an Ir receiver linked to a parallel port error line using cheap Radio Shack parts, but I wonder if someone knows of a stock PC Ir receiver for either USB or serial that can take in data from an HP calculator Ir transmitter. Thanks. I wrote a DOS program to decode the data for a dumb IR->Wire hardware interface, something like the Radio Shack one, in the early 90'ties. Therefore I used one of the modem status input lines of the serial interface. But this solution caused several problems:
But who has nowadays real DOS machines? So my solution and IMHO the only realistic solution nowadays is an intelligent hardware converting the HP-Redeye protocol into another more useable (Serial RS232C, USB, ...) one. My solution for RC232C is very simple from the hardware aspect. A microcontroller, an integrated IR-receiver chip (Temic TSOP1833), inverting the TXD signal, and a very simple power logic. But the software is the expensive part and in my case I haven't the rights to publish them. Regards Christoph ▼
06-05-2003, 06:07 AM
Quote:
I stand corrected. I was thinking that the HP Red Eye printer protocol
I don't know which calculators Randy has in mind, but with the 48
Since IR I/O is half-duplex (because of the likelyhood of reflected
If you set flag -33 ("I/O directed to IR port"), and set flag -34 See the documents mentioned earlier in the thread for more information.
Regards, Edited: 5 June 2003, 6:14 a.m. ▼
06-05-2003, 02:25 PM
> I stand corrected. I was thinking that the HP Red Eye printer protocol was 2400 bps, but it's actually much lower, and when you consider that the Red Eye protocol includes 4 error correction bits with each byte, then it's effectively about the same as 600 bps RS-232. This isn't correct, you can't compare the 416us (2400 baud) bit time of the Serial InfraRed protocol with the 427us _half_ bit time of the HP REDEYE HP82240B printer protocol. Both protocols use a complete different framing. The original question from Randy was asking for a receiver to capture the HP82240B printer protocol (HP REDEYE) data and not for a Serial InfraRed (SIR) reader. The ~600 baud of HP REDEYE HP82240B printer protocol mentioned in my prior posting is calculated by baud = 1 / ((pulse/freq) * d * hframes) * bitsperbyte with
the final baud rate is baud = 1 / ((7/32768) * 2 * 30) * 8 = 624 Randy though about the HP17B, HP17BII, HP18C, HP19B, HP19BII, HP27S, HP28C, HP28S, HP41 with Ir printer module, HP42S calculators (hopefully I forgot none) which all only can send data in the HP REDEYE HP82240B printer and not the Serial InfraRed protocol. But these 624 / 8 = 78 bytes/sec are only theoretically, the transmitter routine has to disable interrupts and has the calculate the 4 error correction bits and a little bit more at runtime so you have at least about 70 bytes/sec on these calculators.
This is correct, but wasn't asked. Further information about connecting a HP48 over Serial InfraRed protocol to a PC can be found at http://www.hpcalc.org/details.php?id=4856. Best Regards, Christoph Giesselink, Homepage ▼
06-05-2003, 08:48 PM
Hi Christoph,
Quote:
Apparently we basically agree on a lot of this, but perhaps I don't
For the RedEye encoding used for the 82240A/B: "A bit time is defined as
For 2400 bps RS-232, a bit-time is of course 1/2400 second, or about 417
Of course the 48 doesn't allow for 600 bits per second. But if it did,
Quote:
Sorry, I didn't read Randy's mind, but just what he'd actually written
Even if what I've written doesn't help Randy, perhaps it will help
Of course a RedEye to RS-232 adapter could be built, but it would be
Best Regards,
06-09-2003, 04:06 PM
James & Christoph: Thanks for taking the time to share some of your knowledge base. Your insights have been very helpful. A redeye to serial adapter would be perfect because what I use now is HPIL to serial to send ASCII strings to be captured by a PC. I add coma delimeters in the RPN program which I then import into Excel, then into AutoCad because part of the ASCII string generation calculates geographic coordinates. I don't mind having the wire, but it would be nicer without. The HP 41 acts as a paperweight as I move it around on large maps to analyze and collect the data. It's like a very smart mouse I guess. A very smart wireless mouse would be nice. I'm hooked on pure RPN and the just-right feel of the HP classic case, so I remain a couple decades behind in parts of my technology, but the system is productive. I don't think I'll go much further with redeye thinking because the range is so limited. At one website it was said that HP deliberately kept the redeye range low so students wouldn't send cheat sheets back and forth during exams -- an interesting theory. It's fun to visit this site to learn more, and thanks again! - Randy ▼
06-10-2003, 12:25 PM
> I don't think I'll go much further with redeye thinking because the range is so limited. At one website it was said that HP deliberately kept the redeye range low so students wouldn't send cheat sheets back and forth during exams -- an interesting theory. Only one minor comment. The website is right, when you compare the possible IR distance between HP products. The possible distance over IR are normally between
The reason of this limitation is the IR receiver hardware. My REDEYE receiver using the receiver IC Temic TSOP1833 without any cover (placed behind a hole in the case). I made some distance tests with this reiceiver and my HP48SX and I got possible transmitting distances between some millimeter up to 8 meter indoors (the room wasn't bigger, so the possible receiving distance maybe greater)! So the distance is no limitation IMHO. Hope one of your HP's is working to transfer the European length units into your favorite ones. :) Regards Christoph |