SDRAM Interface
9-40
9.4.9.2
TMS320C6211
/
C6711 SDRAM Write
All SDRAM writes have a burst length of four on the ’C6211/C6711. The bank is
activated with the row address during the ACTV command. There is no latency
on writes, so data is output on the same cycle as the column address. Writes to
particular bytes are disabled via the appropriate DQM inputs; this feature allows
for byte and halfword writes. Figure 9–27 shows the timing for a three-word write
on the ’C6211/C6711. Since the default ’C6211/C6711 write-burst length is four
words, the last write is masked out via the byte enable signals. On the
’C6211/C6711, idle cycles are inserted as controlled by the parameters of the
SDRAM extension register fields (WR2RD, WR2DEAC, WR2WR, TWR). The
bank is then deactivated with a DEAC command for ’C6211/C6711, and the
memory interface can begin a new page access. If no new access is pending,
the DEAC command is not performed until the page information becomes inval-
id (see section 9.4.2). The values on EA[15:13] during column accesses and
the DEAC command are the values latched during the ACTV command.
Figure 9–27. TMS320C6211/C6711 SDRAM Three Word Write
SDWE
SDCAS
SDRAS
ED[31:0]
EA12
EA[11:2]
EA[21:13]
BE[3:0]
CEx
ECLKOUT
D3
D2
D1
Column
Bank
BE4
BE3
BE2
BE1
Write
ÁÁ
Á
SDRAM
latches
D1
SDRAM
latches
D2
SDRAM
latches
D3
D4
blocked by BEx high