SA1110 Datasheet, PDF (138/406 Pages) Intel Corporation – Intel StrongARM SA-1110 Microprocessor

Memory and PCMCIA Control Module
0h A000 0018
MECR
Read/Write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reset ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
(Sheet 2 of 2)
Bits
Name
Description
Fast mode bit for access to slot 1 I/O, attribute, or memory.
If FAST1=1, the set-up time from address generated signals (A, nPREG, PSKTSEL and
nPCE) to initial assertion of the read or write strobe (nPWE, nPIOW, nPOE, or nPIOR) is
1*(BS_xx + 1) + 1 instead of the normal 3*(BS_xx + 1) + 1.
31
FAST1
During I/O accesses, the nPCE set-up time is always reduced from these values by any
A-to-nIOIS16 delay.
The set-up time from address generated signals to the assertion of the read or write strobe
for the second half of a 16-bit access to 8-bit I/O is 2*(BS_xx + 1) instead of 1*(BS_xx + 1).
The duration of the read or write strobe remains 3*(BS_xx + 1), regardless of the value of
FAST1.
Table 10-4. BS_xx Bit Encoding
Bit
4..0
Name
BS_xx
Description
0b00000 – BCLK= 2 processor clocks (clk/2)
0b00001 – BCLK= 4 processor clocks
0b00010 – BCLK= 6 processor clocks
....
0b11101 – BCLK= 60 processor clocks
0b11110 – BCLK= 62 processor clocks
0b11111 – BCLK= 64 processor clocks
Table 10-5. BCLK Speeds for 160-MHz Processor Core Frequency
BS_xx
0b00000 – Every 2 processor clocks (clk/2).
0b00001 – Every 4 processor clocks.
0b00010 – Every 6 processor clocks.
0b00011 – Every 8 processor clocks.
...
0b11111 – Every 64 processor clocks.
12.5
25
37.5
50
400
BCLK Cycle Time–ns
To calculate the recommended BS_xx value for each address space: divide the command width
time (the greater of twIOWR and twIORD, or the greater of twWE and twOE) by processor cycle
time; divide by 2; divide again by 3 (number of BCLK’s per command assertion); round up to the
next whole number; and subtract 1. For example, for a processor cycle time of 6.25 ns and an
nIOWR command assertion time of 165 ns, the recommended setting for BS_IO would be
(165 /(2 x 3 x 6.25)) - 1 = 3.4, or 4 after rounding up.
10-24
SA-1110 Developer’s Manual