pic24 and the pmp and eds

[smee]

hi everyone

i am using the pic24fj256gb210 and the com20020i 3.3v arcnet chip.
i have previously been bit banging the signals but even with the pll on it has proved to be a bit slow.

so now i plan to interconnect the two with the pmp and use the eds so that i can access the chip with the cpu mov instructions.

it is however my first time with the pmp, and i was hoping that any members with experience of the pmp would comment on my setup.

the com20020 is essentially a 8 byte memory device.
having d0..d7 WR RD CS A0 A1 A2 reset INT pins

i have

data lines d0 .. d7 of the com20020 connected to port E0..E7
A1 connected to pin b14 ( PMA1 )
A0 connected to pin b15 (PMA0)
A2 connected to pin g9 (PMA2)
CS connected to pin E8 (PMCS1)
WR connected to pin d4 (PMWR)
RD connected to pin d5 (PMRD)

reset connected to pin e9
INT connected to pin d7


it seems fairly straight forward, but i am asking in case i have made a stupid mistake which is not unheard of.

thankyou.

[Ttelmah]

You may need to look carefully at the timings. The read/write to address pointer low register, following accessing a data register, needs an extra delay. You may need to add this yourself in software.

[smee]

Can i add this delay through the no of wait states setting of the pmp?

I was hoping to use the mov and repeat instructions to access the com200 as i will be running the network at either 2.5mbs or 5mbs. And i did want the access to the chip to be completely automatic, and at the cpu's native speed.

[Ttelmah]

I'd suggest, that successive reads or writes, which don't need this delay, could be done as you describe, but it'd probably be easier to do the 'setup' accesses with extra delays added directly. Otherwise you would delay all the other accesses, which seems a little pointless.