>Hi,
>
>   has anyone got a neat way to interface photodiodes to a pic? Ideally I
>would like to hang four of them on a 16C84 and still have some pins left to
>display the results.
>
>So far the best I have come up with is to use the photodiodes as current
>sources to charge a capacitor. Use a low leakage FETs to discharge the
>capacitors and  comparators to signal when the voltage exceeds a preset level.
>
>This involves quite a lot of components (capacitors, quad comparator, FETS,
>voltage reference) and isn't particularly easy  to set up. Has anyone found
>a neater and more linear solution?
>
>Keith
>==========================================================
>Keith Dowsett         "Variables won't; constants aren't."
>
>E-mail:      kdowsett@rpms.ac.uk
>Phone:       0181-740-3162
>Fax:         0181-743-3987
>
>Snail mail:  MRC Clinical Sciences Centre, Cyclotron Unit.
>                 Hammersmith Hospital. London W12 0NN.
>
Keith,

to answer your question more info is needed. What light levels resp. photo
currents, what 
temperature range and what timing is required.

Ciao, Claus
===========================================================================
Dr. Claus KŸhnel                                    Tel/Fax +41 1 785 02 75
Consulting & Distribution                     E-Mail  kuehnel@dial.eunet.ch
                                                     ckuehnel@access.ch
===========================================================================