![Texas Instruments AM1808 Technical Reference Manual Download Page 267](http://html.mh-extra.com/html/texas-instruments/am1808/am1808_technical-reference-manual_1094558267.webp)
SYSCFG Registers
267
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
System Configuration (SYSCFG) Module
10.5.14 Chip Configuration 0 Register (CFGCHIP0)
The chip configuration 0 register (CFGCHIP0) controls the following functions:
•
PLL Controller 0 memory-mapped register lock: Used to lock out writes to the PLLC0 memory-mapped
registers (MMRs) to prevent any erroneous writes in software to the PLLC0 register space.
•
EDMA3_0 Transfer Controller Default Burst Size (DBS) Control: This controls the maximum number of
bytes issued per read/write command or the burst size for the individual transfer controllers (TCs) on
the device. By default for all transfer controllers, the burst size is set to 16 bytes. However, CFGCHIP0
allows configurability of this parameter so that the TC can have a burst size of 16, 32, or 64 bytes. The
burst size determines the intra packet efficiency for the EDMA3_0 transfers. Additionally, it also
facilitates preemption at a system level, as all transfer requests are internally broken down by the
transfer controller up to DBS size byte chunks and on a system level, each master’s priority
(configured by the MSTPRI register) is evaluated at burst size boundaries. The DBS value can
significantly impact the standalone throughput performance depending on the source and destination
(bus width/frequency/burst support etc) and the TC FIFO size, etc. Therefore, the DBS size
configuration should be carefully analyzed to meet the system’s throughput/performance requirements.
The CFGCHIP0 is shown in
and described in
.
Figure 10-41. Chip Configuration 0 Register (CFGCHIP0)
31
16
Reserved
R-0
15
5
4
3
2
1
0
Reserved
PLL_MASTER_LOCK
EDMA30TC1DBS
EDMA30TC0DBS
R-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 10-45. Chip Configuration 0 Register (CFGCHIP0) Field Descriptions
Bit
Field
Value
Description
31-5
Reserved
0
Reserved.
4
PLL_MASTER_LOCK
PLLC0 MMRs lock.
0
PLLC0 MMRs are freely accessible.
1
All PLLC0 MMRs are locked.
3-2
EDMA30TC1DBS
EDMA3_0_TC1 Default Burst Size (DBS).
0
16 bytes
1h
32 bytes
2h
64 bytes
3h
Reserved
1-0
EDMA30TC0DBS
EDMA3_0_TC0 Default Burst Size (DBS).
0
16 bytes
1h
32 bytes
2h
64 bytes
3h
Reserved