NXP Semiconductors LPC24XX UM10237 - Manual (Page 35)

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User manual Rev. 04 — 26 August 2009 35 of 792
NXP Semiconductors
UM10237
Chapter 3: LPC24XX System control
[1] Allowed values for nnn are: 101 (highest priority), 100, 011, 010, 001 (lowest priority).
Table 30. AHB Arbiter Configuration register 1 (AHBCFG1 - address 0xE01F C188) bit
description
Bit Symbol Value Description Reset
value
0 scheduler 0 Priority scheduling. 1
1 Uniform (round-robin) scheduling.
2:1 break_burst 00 Break all defined length bursts (the CPU does not create
defined bursts). 10
01 Break all defined length bursts greater than four-beat.
10 Break all defined length bursts greater than eight-beat.
11 Never break defined length bursts.
3 quantum_type 0 A quantum is an AHB clock. 0
1 A quantum is an AHB bus cycle.
7:4 quantum_size Controls the type of arbitration and the number of quanta
before re-arbiration occurs. 0100
0000 Preemptive, re-arbitrate after 1 AHB quantum.
0001 Preemptive, re-arbitrate after 2 AHB quanta.
0010 Preemptive, re-arbitrate after 4 AHB quanta.
0011 Preemptive, re-arbitrate after 8 AHB quanta.
0100 Preemptive, re-arbitrate after 16 AHB quanta.
0101 Preemptive, re-arbitrate after 32 AHB quanta.
0110 Preemptive, re-arbitrate after 64 AHB quanta.
0111 Preemptive, re-arbitrate after 128 AHB quanta.
1000 Preemptive, re-arbitrate after 256 AHB quanta.
1001 Preemptive, re-arbitrate after 512 AHB quanta.
1010 Preemptive, re-arbitrate after 1024 AHB quanta.
1011 Preemptive, re-arbitrate after 2048 AHB quanta.
1100 Preemptive, re-arbitrate after 4096 AHB quanta.
1101 Preemptive, re-arbitrate after 8192 AHB quanta.
1110 Preemptive, re-arbitrate after 16384 AHB quanta.
1111 Non- preemptive, infinite AHB quanta.
10:8 default_master nnn [1] Master 1 (CPU) is the default master. 001
11 - - Reserved. -
14:12 EP1 nnn [1] External priority for master 1 (CPU). 000
15 - - Reserved. -
18:16 EP2 nnn [1] External priority for master 2 (GPDMA). 000
19 - - Reserved. -
22:20 EP3 nnn [1] External priority for master 3 (AHB1). 000
23 - - Reserved. -
26:24 EP4 nnn [1] External priority for master 4 (USB). 000
27 - -- Reserved. -
30:28 EP5 nnn [1] External priority for master 5 (LCD). 000
31 - - Reserved. -