AT32UC3C1512C Automotive Atmel Corporation, AT32UC3C1512C Automotive Datasheet - Page 352

• Manufacturer Part Number: AT32UC3C1512C Automotive
• Manufacturer: Atmel Corporation

Figure 19-4. Write Burst, 16-bit SDRAM Access
19.7.3
9166C–AVR-08/11
SDRAMC_A[12:0]
D[15:0]
SDWE
SDCS
SDCK
SDRAM Controller Read Cycle
RAS
CAS
The SDRAMC allows burst access, incremental burst of unspecified length or single access. In
all cases, the SDRAMC keeps track of the active row in each bank, thus maximizing perfor-
mance of the SDRAM. If row and bank addresses do not match the previous row/bank address,
then the SDRAMC automatically generates a precharge command, activates the new row and
starts the read command. To comply with the SDRAM timing parameters, additional clock cycles
on SDCK are inserted between precharge and active (t
read (t
read command, additional wait states are generated to comply with the CAS latency (one, two,
or three clock delays specified in the CR register).
For a single access or an incremented burst of unspecified length, the SDRAMC anticipates the
next access. While the last value of the column is returned by the SDRAMC on the bus, the
SDRAMC anticipates the read to the next column and thus anticipates the CAS latency. This
reduces the effect of the CAS latency on the internal bus.
For burst access of specified length (4, 8, 16 words), access is not anticipated. This case leads
to the best performance. If the burst is broken (border, busy mode, etc.), the next access is han-
dled as an incrementing burst of unspecified length.
Row n
t
RCD
RCD
= 3
) commands. These two parameters are set in the CR register of the SDRAMC. After a
Col a
Dna
Col b
Dnb
Col c
Dnc
Col d
Dnd
Col e
Dne
Col f
Dnf
Col g
Dng
RP
) commands and between active and
Col h Col i
Dnh
Dni
Col j
Dnj
AT32UC3C
Col k
Dnk
Col l
Dnl
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