Hello all,

We have been designing a small-scale scientific payload (as a mainly
students oriented research project)
which will be deployed on a NASA rocket to measure some atmospheric variabl=
es.

We have almost finalized our circuitries. However, there is one design
challenge that we are not sure of how to
tackle. That is we want to interface a particle counter to our system.
The particle counter in this context gives us
an analogue output (10 mV - 5V) based on the particle size that its
laser reads. Further on we will save the content
into a flash drive that our PIC18F2523 interfaces via the SPI port.

We need to be able to sample at least 100 ksps which is double the
speed what the PIC can do. So we have decided
to use an external A/D converter (which is a 12-bit 100 ksps A/D
circuitry with digital output feature:
http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=3Den010531)

With the same PIC we wil do 3 more A/D readings and saving operations
while working at 10Mhz x 4 =3D 40Mhz max speed.

My questions: Is this a good approach to handle this problem? I am
wondering how much of the analog data from the counter
can safely be written into the flash (I was almost forgetting with a
time-stamp for each sample)? Should I switch to a faster MCU or
DSP?

I would be glad to learn your opinions on this matter.

Thank you,
G=F6khan

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