EMC Burst Buffer
Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
Freescale Semiconductor
17-3
17.1.2
Features
The EMC Burst Buffer includes the following features:
•
A simple burst cache enables burst accesses, including four burst buffers.
•
Executes burst from Shared Bus masters based solely on the address being accessed.
•
Fire-and-forget single write access.
•
Zero wait state access for writes and reads that hit within the burst buffer.
•
Read data returned are always zero if no access happens.
17.2
Memory Map and Register Definition
No registers or memory are in this block.
17.3
Functional Description
The following sections describe the arbiter functionality: address scope, burst control, read access and
write access. The module can execute burst read/write transfers because there is a small burst cache with
two 8-word buffers for both burst read and burst write. All outputs will not be registered, so a one cycle
delay is avoided in transfers. All reads to entries within the burst buffer finish with zero wait states, while
writes to an entry within a burst buffer (if there is room) also finish with zero wait states.
Four burst buffers are included in the burst cache of the gasket for Shared Bus master 0 read, Shared Bus
master 0 write, Shared Bus master 1 read, and Shared Bus master 1 write respectively. Each buffer has 16
24-bit words alternating (ping-pong operation) between the two sets of 8. Burst operation can be controlled
by configuring the corresponding register bits in the Chip Configuration module in the DSP56724.
17.3.1
Burst Control
There are control bits in the EMBC (External Memory Burst Control) register for burst access control of
X, Y, and P external memory space.
•
Bits 3-0 of the EMBC register are named the “X Space Burst Boundary”, and these bits define the
1M burst region in the X external memories.
•
Bits 11-8 of the EMBC register are named the “Y Space Burst Boundary”, and these bits define the
1M burst region in the Y external memories.
•
Bits 19-16 of the EMBC register are named the “P Space Burst Boundary”, and these bits define
the 1M burst region in the P external memories.
For more information about these bits or the EMBC register, see
Chapter 20, “Chip Configuration
In the EMBC register, the two EXMBC bits, two EYMBC bits, and two EPMBC bits control the burst
behavior of X, Y, and P external memories, as shown in
.
Содержание Symphony DSP56724
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