at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 199

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

22. SDRAM Controller (SDRAMC)
22.1
22.2
6384B–ATARM–15-Dec-08
Overview
I/O Lines Description
The SDRAM Controller (SDRAMC) extends the memory capabilities of a chip by providing the
interface to an external 16-bit or 32-bit SDRAM device. The page size supports ranges from
2048 to 8192 and the number of columns from 256 to 2048. It supports byte (8-bit), half-word
(16-bit) and word (32-bit) accesses.
The SDRAM Controller supports a read or write burst length of one location. It keeps track of the
active row in each bank, thus maximizing SDRAM performance, e.g., the application may be
placed in one bank and data in the other banks. So as to optimize performance, it is advisable to
avoid accessing different rows in the same bank.
The SDRAM controller supports a CAS latency of 1, 2 or 3 and optimizes the read access
depending on the frequency.
The different modes available - self-refresh, power-down and deep power-down modes - mini-
mize power consumption on the SDRAM device.
Table 22-1.
Name
SDCK
SDCKE
SDCS
BA[1:0]
RAS
CAS
SDWE
NBS[3:0]
SDRAMC_A[12:0]
D[31:0]
I/O Line Description
Description
SDRAM Clock
SDRAM Clock Enable
SDRAM Controller Chip Select
Bank Select Signals
Row Signal
Column Signal
SDRAM Write Enable
Data Mask Enable Signals
Address Bus
Data Bus
AT91SAM9G20 Preliminary
Output
Output
Output
Output
Output
Output
Output
Output
Output
Type
I/O
Active Level
High
Low
Low
Low
Low
Low
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