UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
108 of 1269
NXP Semiconductors
UM10503
Chapter 11: LPC43xx Clock Generation Unit (CGU)
case 1: x = 0x00018003;
case 2: x = 0x00010003;
default: for (i = M; i <= M_max; i++)
x = (((x ^ (x>>1)) & 1) << 14) | ((x>>1) & 0x3FFF); }
MDEC[16:0] = x;
The values for SELP, SELI, and SELR depend on the value for M as expressed by the
following pseudo-code:
if (M < 60) then
SELP = (M>>1) + 1
else
SELP = 31;
if (M > 16384) then
SELI = 1
else if (M > 8192) then
SELI = 2
else if (M > 2048) then
SELI = 4
else if (M >= 501) then
SELI = 8
else if (M >=60) then
SELI = 4*(1024/(M+9))
else
SELI = (M & 0x3C) + 4; /* & denotes bitwise AND */
SELR = 0;
11.6.3.4 PLL0USB NP-divider register
Remark:
The PLL NP-divider register does not use the direct binary representations of N
and P directly. Instead, it uses encoded versions NDEC and PDEC of N and P
respectively.
•
The valid range for N is from 1 to 2^8. This value is encoded into a 10-bit NDEC value.
The relationship can be expressed through the following pseudo-code:
N_max=0x00000100, x=0x00000080;
switch (N) {
case 0: x = 0xFFFFFFFF;
case 1: x = 0x00000302;
case 2: x = 0x00000202;
Table 72.
PLL0USB M-divider register (PLL0USB_MDIV, address 0x4005 0024) bit
description
Bit
Symbol
Description
Reset
value
Access
16:0
MDEC
Decoded M-divider coefficient value. Select values for
the M-divider between 1 and 131071.
0x5B6A
R/W
21:17
SELP
Bandwidth select P value
11100
R/W
27:22
SELI
Bandwidth select I value
010111
R/W
31:28
SELR
Bandwidth select R value
0000
R/W