at91cap7e ATMEL Corporation, at91cap7e Datasheet - Page 177

• Manufacturer Part Number: at91cap7e
• Description: Customizable Microcontroller
• Manufacturer: ATMEL Corporation

Figure 22-1. SDRAM Device Initialization Sequence
22.5.2
22.5.3
22.6
22.6.1
8549A–CAP–10/08
SDRAMC_A[12:11]
SDRAMC_A[9:0]
SDCKE
SDWE
SDCK
SDCS
RAS
CAS
NBS
A10
Functional Description
I/O Lines
Interrupt
SDRAM Controller Write Cycle
Inputs Stable for
200 μsec
The pins used for interfacing the SDRAM Controller may be multiplexed with the PIO lines. The
programmer must first program the PIO controller to assign the SDRAM Controller pins to their
peripheral function. If I/O lines of the SDRAM Controller are not used by the application, they
can be used for other purposes by the PIO Controller.
The SDRAM Controller interrupt (Refresh Error notification) is connected to the Memory Control-
ler. This interrupt may be ORed with other System Peripheral interrupt lines and is finally
provided as the System Interrupt Source (Source 1) to the AIC (Advanced Interrupt Controller).
Using the SDRAM Controller interrupt requires the AIC to be programmed first.
The SDRAM Controller allows burst access or single access. In both cases, the SDRAM control-
ler keeps track of the active row in each bank, thus maximizing performance. To initiate a burst
access, the SDRAM Controller uses the transfer type signal provided by the master requesting
the access. If the next access is a sequential write access, writing to the SDRAM device is car-
ried out. If the next access is a write-sequential access, but the current access is to a boundary
page, or if the next access is in another row, then the SDRAM Controller generates a precharge
command, activates the new row and initiates a write command. To comply with SDRAM timing
Precharge All Banks
t
RP
1st Auto-refresh
8th Auto-refresh
t
RC
MRS Command
AT91CAP7E
t
MRD
Valid Command
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