UM10503
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© NXP B.V. 2012. All rights reserved.
User manual
Rev. 1.3 — 6 July 2012
112 of 1269
NXP Semiconductors
UM10503
Chapter 11: LPC43xx Clock Generation Unit (CGU)
11.6.4.4 PLL0AUDIO 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 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;
default: for (i = N; i <= N_max; i++)
x = (((x ^ (x>>2) ^ (x>>3) ^ (x>>4)) & 1) << 7) | ((x>>1) & 0x7F); }
NENC[9:0] = x;
•
The valid range for P is from 1 to 2^5. This value is encoded into a 7-bit PDEC value.
The relationship can be expressed through the following pseudo-code:
P_max=0x00000200, x=0x00000010;
switch (P) {
case 0: x = 0xFFFFFFFF;
case 1: x = 0x00000062;
case 2: x = 0x00000042;
default: for (i = P; i <= P_max; i++)
x = (((x ^ (x>>2)) & 1) << 4) | ((x>>1) & 0xF); }
PDEC[6:0] = x;
Table 76.
PLL0AUDIO M-divider register (PLL0AUDIO_MDIV, address 0x4005 0034) 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
31:17
-
Reserved
-
-
Table 77.
PLL0 AUDIO NP-divider register (PLL0AUDIO_NP_DIV, address 0x4005 0038) bit
description
Bit
Symbol
Description
Reset
value
Access
6:0
PDEC
Decoded P-divider coefficient value
000 0010
R/W
11:7
-
Reserved
-
-
21:12
NDEC
Decoded N-divider coefficient value
1011 0001
R/W
31:22
-
Reserved
-
-