Ive been reading the SA110 and 21285 documentation (learning :), and Ive
hit a snag I cant seem to get my head round...
firstly (related) I assume the diagram on page 4-5 of the 21285 docs
should read [23:2] for the ROM address lines...
On to the problem...
Im "playing with" a design for a system, which would use 32 bit ROM,
which would not be written to. as far as I can see, I would, therefore,
have to hook up the following:
21285 rom_ce_l to the ROM chip enable line
D[31:0]
A[30] = ROM O/p enable
A[23:2] = ROM A[21:0]
this seems to me to imply that only full word reads are possible to 32
bit ROM (which is fine AFAICT)
it also implies (again AFAICT) that ROM is accessible if the SA gives
any address of the form 0x4xxxxxxx.
I assume, then, that the 21285 will only assert rom_ce_l if the address
is of the form 0x41xxxxxx.
The documentation also states that ROM is mapped in on every 16MB
boundary,
until the first write from the SA.
so, since the SA starts executing from 0x00000000, does this mean that
after a reset, and until the first SA write, rom_ce_l is 1, and after is
0 unless the SA address is of the form 0x41xxxxxx
Is this all correct?
Is Manual page 4-5 wrong?
Can anyone recommend a 32 bit wide, 66MHz, 32Mbit flash device?
Oblinux: the device will run linux eventually :)
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