Message #5 Posted by Tony Duell on 27 June 2001, 2:13 p.m., May I also suggest you to see interesting postings/articles here at the Museum, by Steve from Australia, in which he describes his succesful intents on capturing the IR pulse stream and decoding it on a PC. The "odd" thing (no pun intended) was that the parity bits were explained as the logic AND of each group, instead of the logic XOR, which is far more "logic" (again, no pun intended).Ĭertainly XOR is a more useful function in this case, the reported use of AND puzzled me as much as to remember the issue some 12 years after seeing that publication. Just from my memory (I may be wrong) I remember an HP Journal issue (around mid 1988) where the 82240 protocol was described. Tony: thank you for this detailed description! If you just want to decode the IR stream sent by some other device, then you can ignore the parity bits. The idea is that single-bit errors can be corrected. That is to say, the bit together with its group forms an _even_ parity set. They are set if the total number of 1's in each group (which I'll give below) is odd. The last 8 bits (7.0) are the 8 bit ASCII code for the character. Then there must be at least 3 half-bit-times when nothing is sent.Īs I said, a character is 12 bits long. The start of a character is defined by IR bursts in 3 consecutive half-bit-times (this can occur nowhere else in the character, of course). A '0' bit is sent by a IR burst at the start of the second half-bit-time - 14 cyles of nothing, 7 when the IR LED is turned on by the clock, 7 more cyles of nothing. It is important, it appears, that all those pulses should be full-width - no 'runts' at the start or end of the burst.Ī '1' bit is sent by having an IR burst at the start of the first half-bit-time - that is to say 7 clock cycles when the IR LED Is turned on by the clock, then 21 cycles where nothing is emitted. The IR 'burst' is 6-8 pulses of the master clock at 50% mark-space ratio. 1 half-bit-time is defined as 14 cycles of that clock, so not suprisingly a full bit time is 28 cycles. This is written assuming you want to drive the printer from some other device (rather than decode the IR stream from a device designed to talk to the printer), but it may be some help.Įverything is timed from a 32768Hz clock. The HP spec for talking to the IR printer. I knew I had it somewhere, and I've found it. Message #3 Posted by Tony Duell on 26 June 2001, 7:12 p.m., Message #2 Posted by Steve (Australia) on 22 June 2001, 6:34 a.m., If anybody could offer any help or suggestions I would greatly appreciate it! I did find a printer emulator but still have the problem of the IR to RS232 conversion. I cant seem to find any info on the printer as far as protocol, baud rate, etc. I would like to build an IR reciever to hook up to RS232 port. It looks like the keypad only transmits IR(no recieve diode). I have purchased a IEI Keypad for access control that will print its buffer to the HP82240B printer. Message #1 Posted by John V on 21 June 2001, 4:03 p.m. Presentation of a proximity card or keypad entry of a code activates one or both of the output relays which releases an electric door lock.HP82240B IR Printer Protocol The Museum of HP Calculators Each user is assigned a proximity card and/or a personal identification number (PIN). SDC’s 921P models are indoor/outdoor standalone digital keypads with proximity reader and controller (two-piece configuration), designed to control access of a single entry point with up to 500 users. 920PW models are designed to interface with SDC’s IPPro® or most access control systems providing a standard 26-bit wiegand output. Featuring heavy cast vandal resistant housing and cast metal blue backlit keys.ĩ20P models add HID proximity reader capability to the keypad. Keypad entry of a valid one to six digit code activates one or both of the output relays which releases an electric door lock. Each user is assigned a personal identification number (PIN). SDC’s Entr圜heck™ 920 series indoor/outdoor digital keypads are designed to control access of a single entry point with up to 500 users.
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