> Hi All,
>
>     I've been lurking around on this list for a couple years and
> am finally
> about to embark on my first serious PIC project. It is a
> university project.
> A group of aeronautical engineering students and I want to build a tiny
> black box for a model airplane, to aquire 8-12 channels of analog data.
> Before I ask my questions, here is what I have planned to use so far:
>
> 16F877 for 8 channels, 10 bits
> 24FC256 serial eeprom - 256k of data storage
> PICALL Programmer
>
>     This should provide at least 10 min of storage at 30
> samples/sec, using
> 3 bytes for every 2 samples. My main concern is that we may need more
> channels, up to 10 or 12. I see at least one 16 and some 17 and 18 series
> PICs that are up for the job. I have two concerns about these alternate
> chips though, these parts aren't the flash type - I noticed they
> use the 'C'
> denotation instead of the 'F' in their names - does this mean for
> every code
> revision I will need a new chip?
>
>     Also, for the 17 and 18 series chips it seems I will need a different
> programmer. Is there a cheap programmer for the 17 and 18 series
> chips that
> I should go with from the start?
>
>     I was also considering using a pin on the 16F877 to switch between two
> sets of 8 analog inputs, using eight 2x1 muliplexers. I would read 8
> channels into RAM, switch with the muxes, read the second 8
> channels to RAM,
> and then output to the eeprom. Would that work? I've never heard of
> multiplexers switching analog inputs, so I am a little concerned there.

        Is this a one off or will it go into production? Since you are already
thinking of adding a second chip (the mux) how about adding an I2C ADC?
Maxim has an 8ch 10bit one that would fit the bill perfectly, and since you
are already doing I2C (for the EEPROM) adding it would be trivial from a
hardware and code point of view? Thanks, TTYL

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