Programming Model
http://www.mcg.mot.com/literature
3-39
3
BCK5-BCK0 The refresh rate is defined by the following equation:
Refresh Rate = BCK/BUS CLOCK * 16
where BCK is the value programmed in the Bus Clock
Register, and BUS CLOCK is the MC68xx060 bus clock
frequency.
PROM Access Time Control Register
The MVME172 is populated with a 150ns PROM memory device. Due to
the wide range of PROM speeds, the contents can be changed by software
to adjust for a specific speed.
ET2-ET0
PROM access time is controlled by the state of ET2-ET0.
The following table defines the ET2-ET0 encoding (note
that for the MVE172, whose bus frequency is
1
/
2
the
processor frequency, only the 33MHz column applies).
ADR/SIZ
$FFF42040 (8 bits)
BIT
23
22
21
20
19
18
17
16
NAME
ROM0
ET2
ET1
ET0
OPER
R
R
R
R/W
R
R/W
R/W
R/W
RESET
0
0
0
1 PL
0
1 PL
1 PL
1 PL
ET2-
ET0
PROM Access <= N
at 25 MHz where N =
PROM Access <= N
at 33 MHz where N =
$0
60 ns
40 ns
$1
100 ns
70 ns
$2
140 ns
100 ns
$3
180 ns
130 ns
$4
220 ns
160 ns
$5
260 ns
190 ns
$6
300 ns
210 ns
$7
340 ns
240 ns
Содержание MVME172
Страница 1: ...MVME172 VME Embedded Controller Programmer s Reference Guide VME172A PG2 Edition of February 1999 ...
Страница 6: ...Place holder ...
Страница 18: ...xviii ...
Страница 78: ...1 60 Computer Group Literature Center Web Site Board Description and Memory Maps 1 ...
Страница 332: ...5 42 Computer Group Literature Center Web Site MCECC 5 ...
Страница 336: ...A 4 Related Documentation A ...
Страница 340: ...VMEchip2 Tick Timer 1 Periodic Interrupt Example B 4 Computer Group Literature Center Web Site B ...
Страница 352: ...Index IN 12 Computer Group Literature Center Web Site I N D E X ...
Страница 354: ......