218
Rabbit 2000 Microprocessor
B.2.13 Early Memory Output-Enable Feature
The early I/O enable feature was added to the Rabbit 2000C revision to relax the tight tim-
ing requirements for memory access when using the clock spectrum spreader. The early
I/O option extends the output enable time for the /OEx strobes and the write enable time
for the /WEx strobes by a half clock cycle. The Memory Timing Control Register
(MTCR) enables the extended timing for the memory output enable and write enable
strobes.
Memory read and write timing are discussed further in Chapter 15, “AC Timing Specifica-
tions.”
Table B-12. Memory Timing Control Register
Memory Timing Control Register
(MTCR)
(Address = 0x19)
Bit(s)
Value
Description
7:4
xxxx
These bits are reserved and should not be used.
3
0
Normal timing for /OE1B (rising edge to rising edge, one clock minimum).
1
Extended timing for /OE1B (one-half clock earlier than normal).
2
0
Normal timing for /OE0B (rising edge to rising edge, one clock minimum).
1
Extended timing for /OE0B (one-half clock earlier than normal).
1
0
Normal timing for /WE1B (rising edge to falling edge, one and one-half clocks
minimum).
1
Extended timing for /WE1B (falling edge to falling edge, two clocks
minimum).
0
0
Normal timing for /WE0B (rising edge to falling edge, one and one-half clocks
minimum).
1
Extended timing for /WE0B (falling edge to falling edge, two clocks
minimum).
Содержание 2000
Страница 1: ...Rabbit 2000 Microprocessor User s Manual 019 0069 041018 M...
Страница 12: ...6 Rabbit 2000 Microprocessor...
Страница 46: ...40 Rabbit 2000 Microprocessor...
Страница 54: ...48 Rabbit 2000 Microprocessor...
Страница 76: ...70 Rabbit 2000 Microprocessor...
Страница 96: ...90 Rabbit 2000 Microprocessor...
Страница 142: ...136 Rabbit 2000 Microprocessor...
Страница 154: ...148 Rabbit 2000 Microprocessor...
Страница 170: ...164 Rabbit 2000 Microprocessor...
Страница 174: ...168 Rabbit 2000 Microprocessor...
Страница 180: ...174 Rabbit 2000 Microprocessor...
Страница 202: ...196 Rabbit 2000 Microprocessor...
Страница 206: ...200 Rabbit 2000 Microprocessor...
Страница 226: ......
Страница 230: ...224 Rabbit 2000 Microprocessor...