
Media Local Bus (MLB)
PXN20 Microcontroller Reference Manual, Rev. 1
27-30
Freescale Semiconductor
27.4.4
Local Channel Buffer RAM
A single-port RAM is used to implement the memory space for local channel buffering. The size of the
RAM is 2k x 36-bits (1 quadlet of data; 4-bit tag). The initial start address and depth values for the logical
channels buffered in the RAM are controlled via the LCBCR
n
. After reset, the initial settings can be
overwritten by software.
for more information on using the LCBCR
n
to configure the local RAM buffer.
Figure 27-17. Programming Example for LCBCR
n
27.4.4.1
Local Buffer Start Address
The initial buffer start address of each local channel buffer is defined by the default (after reset) start
address of each local channel buffer (LCBCR
n
[SA[8:0]]). The start address is the location of the beginning
of the buffer in the local buffer RAM. Software may change the start address of each local channel buffer
after reset by writing to LCBCR
n
[SA[8:0]] directly.
27.4.4.2
Local Channel Buffer Depth
The initial buffer depth of each local channel buffer is configured by the default (after reset) depth of each
local channel buffer (LCBCR
n
[BD[8:0]]) in quadlets. The buffer depth should be set based on the
worst-case DMA interface read/write latency. Software may change the depth of each local channel buffer
after reset by writing to LCBCR
n
[BD[8:0]] directly.
Local Channel Buffer 0
LCBCR0.BD
LCBCR0.SA
Local Channel Buffer 2
LCBCR2.BD
LCBCR2.SA
Local Channel Buffer 1
LCBCR1
.BD
LCBCR1.SA
0
2048
36 bits
Summary of Contents for PXN2020
Page 1: ...PXN20 Microcontroller Reference Manual Devices Supported PXN2020 PXN2120 PXN20RM Rev 1 06 2011...
Page 42: ...PXN20 Microcontroller Reference Manual Rev 1 lxiv Freescale Semiconductor...
Page 64: ...Introduction PXN20 Microcontroller Reference Manual Rev 1 1 22 Freescale Semiconductor...
Page 112: ...Signal Description PXN20 Microcontroller Reference Manual Rev 1 3 44 Freescale Semiconductor...
Page 118: ...Resets PXN20 Microcontroller Reference Manual Rev 1 4 6 Freescale Semiconductor...
Page 372: ...e200z6 Core Z6 PXN20 Microcontroller Reference Manual Rev 1 13 8 Freescale Semiconductor...
Page 412: ...e200z0 Core Z0 PXN20 Microcontroller Reference Manual Rev 1 14 14 Freescale Semiconductor...
Page 821: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 Freescale Semiconductor 27 49...
Page 822: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 27 50 Freescale Semiconductor...
Page 1376: ...Memory Map PXN20 Microcontroller Reference Manual Rev 1 A 118 Freescale Semiconductor...