Symphony DSP56724/DSP56725 Multi-Core Audio Processors, Rev. 0
21-62
Freescale Semiconductor
External Memory Controller (EMC)
21.4.3.7.6
External Address and Command Buffers (BUFCMD)
If the additional delay of any buffers placed on the command strobes (LSDRAS, LSDCAS, LSDWE, and
LSDA10), is endangering the device set-up time, SDMR[BUFCMD] should be set. Setting the
SDMR[BUFCMD] bit causes the memory controller to add CRR[BUFCMDC] extra bus cycles to the
assertion of SDRAM control signals (LSDRAS, LSDCAS, LSDWE and LSDA10) for each SDRAM
command.
Figure 21-22. BUFCMD = 1, CRR[BUFCMDC] = 2
21.4.3.8
SDRAM Interface Timing
The following figures show SDRAM timing for various types of accesses.
Figure 21-23. SDRAM Single-Beat Read, Page Closed, CL = 3
Figure 21-24. SDRAM Single-Beat Read, Page Hit, CL = 3
1111
0000
1111
ZZZZZZ RAS ADD
XXXXXXXX
CAS ADD
D3
ZZZZZZZZ
LCLK
LALE
LCSx
LSDRAS
LSDCAS
LSDWE
LSDDQM
LAD
D0
D1
D2
XXXX
Command
setup cycle
Command
setup cycle
1111
0000
1111
ZZZZZZZZ
ZZZZ
ZZZZZZZZ
D0
ZZZZZZZZ
LCLK
LALE
LCSx
LSDRAS
LSDCAS
LSDWE
LSDDQM
LAD[23:0]
COL ADD
ROW ADD
TA
1111
0000
1111
ZZZZZZZZ
COL ADD
ZZZZZZZZ
LCLK
LALE
LCSx
LSDRAS
LSDCAS
LSDWE
LSDDQM
LAD[23:0]
TA
D0