© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
User manual
Rev. 01 — 12 January 2006
43
Philips Semiconductors
UM10161
Volume 1
Chapter 4: MAM Module
4.8 MAM Timing register (MAMTIM - 0xE01F C004)
The MAM Timing register determines how many CCLK cycles are used to access the
Flash memory. This allows tuning MAM timing to match the processor operating
frequency. Flash access times from 1 clock to 7 clocks are possible. Single clock Flash
accesses would essentially remove the MAM from timing calculations. In this case the
MAM mode may be selected to optimize power usage.
4.9 MAM usage notes
When changing MAM timing, the MAM must first be turned off by writing a zero to
MAMCR. A new value may then be written to MAMTIM. Finally, the MAM may be turned
on again by writing a value (1 or 2) corresponding to the desired operating mode to
MAMCR.
For system clock slower than 20 MHz, MAMTIM can be 001. For system clock between
20 MHz and 40 MHz, Flash access time is suggested to be 2 CCLKs, while in systems
with system clock faster than 40 MHz, 3 CCLKs are proposed.
Table 33:
MAM Control Register (MAMCR - address 0xE01F C000) bit description
Bit
Symbol
Value
Description
Reset
value
1:0
MAM_mode
_control
00
MAM functions disabled
0
01
MAM functions partially enabled
10
MAM functions fully enabled
11
Reserved. Not to be used in the application.
7:2
-
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA
Table 34:
MAM Timing register (MAMTIM - address 0xE01F C004) bit description
Bit
Symbol
Value
Description
Reset
value
2:0
MAM_fetch_
cycle_timing
000
0 - Reserved.
07
001
1 - MAM fetch cycles are 1 processor clock (CCLK) in
duration
010
2 - MAM fetch cycles are 2 CCLKs in duration
011
3 - MAM fetch cycles are 3 CCLKs in duration
100
4 - MAM fetch cycles are 4 CCLKs in duration
101
5 - MAM fetch cycles are 5 CCLKs in duration
110
6 - MAM fetch cycles are 6 CCLKs in duration
111
7 - MAM fetch cycles are 7 CCLKs in duration
Warning:
These bits set the duration of MAM Flash fetch operations
as listed here. Improper setting of this value may result in incorrect
operation of the device.
7:3
-
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
NA