James,

     First thoughts for the BINNING is that if you have enough of the 68

     bytes of 16F84 ram spare  (17 * 3 = 51 bytes?), I'd keep the count
     bins in RAM, then say every 5 mins (200 count) I'd dump the whole
lot
     to the E2prom (can be done as 1 page in some (large) E2's

     If your bin limits are fixed at compile time, you could do without
the
     conversion from ASCII to binary, then divide by 36, and just use
     sequential compares straight to the ASCII to decide the bin to put
it
     in.

        Steve Lawther



______________________________ Reply Separator
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Subject: [Q] 16F84 Ultimeter 100 Wind Speed Recording
Author:  James Cameron [SMTP:james.cameron@DIGITAL.COM]  at UKExchange
Date:    11/06/98 10:51


I'm checking the feasibility of a task and I'd appreciate comments on
how to implement it.

I will shortly have a weather monitoring instrument, an Ultimeter 100,
which will provide a 2400 baud data stream containing a wind speed value

calibrated in 0.1kph notches.  The specifications say that it
will be in the form of four ASCII hex bytes; e.g. 30 30 31 30 should
mean 1.0kph.  The samples will arrive at 1.5Hz.

I want to accumulate a histogram in a 16F84's 64 byte EEPROM that
represents the number of samples received from the instrument at each of

17 notches calibrated in metres per second.  Each notch should be three
bytes wide, to allow 2^24 counts per notch.

Looking at this from a software engineering standpoint, I'll need
the following bits of code, which I haven't yet done in PIC, hence the
question ...

        - receive those four bytes and hold them as a number that
          will range from 0 to about 700 (site isn't very windy),

        - divide that number by 36 to get metres per second,

        - increment a specific 24 bit counter in EEPROM.

Hmm.
Hold the number in BCD and do the division in BCD?
Use a lookup table to do the division?
Anyone done anything similar?
Is fetching the EEPROM data via a programmer practical or do I
code a dump-to-serial function too?

ps; I'm new to this list, but not lists in general.

--
James Cameron                              (james.cameron@digital.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800