MAMTIM and MAMCR in LPC
Manual seems to clearly say:

You need both MAMCR and MAMTIM
 Without MAMCR 'it does not hunt'.
 Without setting MAMTIM it appears to hunt randomly. 

MAMCR  

2 bits in MAMCR control what MAM operating mode is used.
 The default setting = 00 which is MAM disabled.
 01 partially enables MAM functions and
 10 enables all MAM functions.
 11 is for when you are feeling bored and wonder what colour smoke it will make. They provide it just to make you curious.

MAMTIM 

3 bits in MAMTIM set flash access cycle count.



User manual around page 105 says:

7.1 MAM Control Register (MAMCR - 0xE01F C000)
 Two configuration bits select the three MAM operating modes, as shown in Table 6–99.
Following any reset, MAM functions are disabled. Software can turn memory access 
acceleration on or off at any time allowing most of an application to be run at the highest 
possible performance, while certain functions can be run at a somewhat slower but more 
predictable rate if more precise timing is required.

Changing the MAM operating mode causes the MAM to invalidate all of the holding 
latches, resulting in new reads of Flash information as required. This guarantees 
synchronization of the MAM to CPU operation.

7.2 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.



ADDED

Question:


sir u want to say that specifying only MAMCR=0x02 will not make the MAM work ?
2 - MAM fetch cycles are 2 CCLKs in duration what does it mean


ANSWER

I want to say, read the manual and user guide in detail and see what all the registers are said to do.   

That is a VERY complicated IC and you must be prepared either to spend the time understanding it, or use something else. 

I have never used this part - I am just used to reading data sheets. It says that if you set MAMCR it WILL work but, IF I read the user guide correctly, it will use the number of clocks per cycle based on MAMTIM contents which are not defined according to this. 

They MAY have been defined somewhere else but you need to know this. 

The default may work Ok BUT you need to know this.