Hi,

there is no need to use one driver per relay, with latching relays use a
matrix. For 32 relays you could use 2 x 373 as latches, with 6 data bits
used in each, and two additional PIC pins used as strobes (total 8 pins
used - but see below for a solution using only 3 pins - chip count == 2
n/incl pic). A set of diodes are required at the drivers to remove the
kickback problem. These are available integrated (in nines even). To steer
the array you first strobe one side of the matrix, then the other, then
turn it off. If you need to steer all the relays statically (not latching)
then it might be better to use a serial in parallel out shift register, or
rather many of these, chained. You'd need four for 32 IOs, using only
three PIC pins. You can use only two shift registers for a matrix of
latching relays (8x8 = 64).  This I have done (with 20 latching reed
relays in a 5x4 crossbar matrix). Note that you may not need to use
separation diodes in the matrix, because the phantom circuits will only
have 1/2 Vcc or less applied and most bistable relays do not change state
under these conditions (you need to check specs).

Peter