UM10413
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User manual
Rev. 1 — 16 December 2011
43 of 268
NXP Semiconductors
UM10413
MPT612 User manual
10.7.1 Memory mapping control register (MEMMAP - 0xE01F C040)
Whenever an exception handling is necessary, the MPT612 fetches an instruction
residing on the exception corresponding address as described in
. Register MEMMAP determines the source of data that fills
this table.
10.7.2 Memory mapping control usage notes
The Memory Mapping Control simply selects one out of three available sources of data
(sets of 64 bytes each) necessary for handling ARM exceptions (interrupts).
For example, whenever a Software Interrupt request is generated, the ARM core always
fetches 32-bit data "residing" on 0x0000 0008 see
. This means that when MEMMAP[1:0] = 10 (User RAM Mode), a
read/fetch from 0x0000 0008 provides data stored in 0x4000 0008. If MEMMAP[1:0] = 00
(Boot Loader Mode), a read/fetch from 0x0000 0008 provides data available also at
0x7FFF E008 (boot block remapped from on-chip Bootloader).
10.8 Phase-Locked Loop (PLL)
The PLL accepts an input clock frequency in the range 10 MHz to 25 MHz only. The input
frequency is multiplied up in the range 10 MHz to 60 MHz using a Current Controlled
Oscillator (CCO). The multiplier can be an integer from 1 to 32; in practice, the multiplier
value cannot be higher than 6 on the MPT612 due to the upper frequency limit of the
CPU. The CCO operates in the range 156 MHz to 320 MHz, so there is an additional
divider in the loop to keep the CCO within its frequency range while the PLL is providing
the desired output frequency. The output divider can be set to divide by 2, 4, 8, or 16 to
produce the output clock. Since the minimum output divider value is 2, it is ensured that
the PLL output has a 50 % duty cycle. A block diagram of the PLL is shown in
PLL activation is controlled via register PLLCON. Register PLLCFG control the PLL
multiplier and divider values. In order to prevent accidental alteration of PLL parameters or
deactivation of the PLL, these two registers are protected. Since all chip operations,
including the watchdog timer, depend on the PLL when it is providing the chip clock,
Table 43.
Memory mapping control register (MEMMAP - address 0xE01F C040) bit
description
Bit
Symbol Value
Description
Reset
value
1:0
MAP
00
Boot loader mode. Interrupt vectors are remapped to boot
block.
00
01
User flash mode. Interrupt vectors are not remapped and
reside in flash.
10
User RAM mode. Interrupt vectors are remapped to static
RAM.
11
reserved; do not use this option
Remark:
improper setting of this value can result in incorrect operation
of the device.
7:2
-
-
reserved, user software must not write logic 1s to reserved
bits; value read from a reserved bit is not defined
n/a