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From: akcs.scotty@hpcvbbs.UUCP (SCOTTY THOMPSON)
Newsgroups: comp.sys.handhelds
Subject: ADCM-48: Attn: J. Wettroth
Keywords: acdm-48, hp48, j. wettroth
Message-ID: <282323ca:3004comp.sys.handhelds@hpcvbbs.UUCP>
Date: 4 May 91 21:40:05 GMT
Lines: 69

John, here are some possible commands for the ADCM-48 (cmds #9-#13)

 
 
 
  REPEAT (2-byte Command)
  
       Repeats the next command the number of  times 
  given in the second argument.
  
  
  SCAN_ANALOG
  
       Sequentially  scans Analog Inputs 1-4 at  .01 
  samples   each   and  returns   a   4-byte   value 
  corresponding to Analog Inputs 1-4, respectively.
  
  
  PUT_SERIAL (2-byte Command)
  
       Sends   the  serial  representation  of   the 
  parallel byte given in the second argument to  the 
  Digital Output referenced in bits 2 and 3 from the 
  first  byte  of this command.  The  bits  will  be 
  clocked  on the falling edge of the Digital  Input 
  referenced in bits 1 and 0 from the first byte  of 
  this command.
  
  
  GET_SERIAL
  
       Receives  the parallel representation of  the 
  serial  byte  received  from  the  Digital   Input 
  referenced  in bits 2 and 3 of the  command.   The 
  bits  will be clocked on the falling edge  of  the 
  Digital  Input referenced in bits 1 and 0  of  the 
  command.
  
  
  BATCH
  
       0:   Indicate Batch Header
       1:   Indicate Batch Footer/Execute Batch
  
       The  ADCM-48  will  store  commands  in  it's 
  command line buffer upon encountering the  BATCH_0 
  command  and continue to store  commands  (without 
  execution)  until receipt of the BATCH_1  command.  
  Upon  receipt of the BATCH_1 command,  the  entire 
  batch  will  be processed.  Using the  REPEAT  and 
  BATCH  commands  can  allow the HP  to  set-up  an 
  initial  programming sequence to the  ADCM-48  and 
  simply  read  and  process the  data  without  re-
  transmitting commands.
 

Also, the pin-diode idea sounds like a good one.  Maybe putting a
bandpass filter on the Rx photodiode will help noise.  Radio-shack has a
part that includes the pin-diode, hi-gain amp, band-pass filter,
demodulator, etc. which would fit nicely in the amount of space that you
already have allocated for the Rx transistor and support components.  I
am able to verify receipt of I/R transmissions over 20 feet away with
this unit.  Unfortunately, the bandpass is set to 100KHz, but reversing
the output (can't remember exactly how I did it) will bypass (seemingly)
the filter and still give good noise immunity and sunlight rejection
while still allowing "AC" signals to pass nicely.

It was a pleasure talking with you.  Thank's again for your advice.
Good luck to you--and let me know how the conference is if I'm unable to
make it!