at91cap7e ATMEL Corporation, at91cap7e Datasheet - Page 180

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

Figure 22-4. Read Burst with Boundary Row Access
22.6.4
180
SDRAMC_A[12:0]
D[31:0]
SDWE
SDCS
SDCK
RAS
CAS
AT91CAP7E
SDRAM Controller Refresh Cycles
col a
Row n
col b
Dna
An auto-refresh command is used to refresh the SDRAM device. Refresh addresses are gener-
ated internally by the SDRAM device and incremented after each auto-refresh automatically.
The SDRAM Controller generates these auto-refresh commands periodically. An internal timer is
loaded with the value in the register SDRAMC_TR that indicates the number of clock cycles
between refresh cycles.
A refresh error interrupt is generated when the previous auto-refresh command did not perform.
It is acknowledged by reading the Interrupt Status Register (SDRAMC_ISR).
When the SDRAM Controller initiates a refresh of the SDRAM device, internal memory accesses
are not delayed. However, if the CPU tries to access the SDRAM, the slave indicates that the
device is busy and the master is held by a wait signal. See
col c
Dnb
col d
Dnc
Dnd
T
RP
= 3
Row m
T
RCD
= 3
col a
CAS = 2
Figure
col b
Dma
col c
22-5.
Dmb
col d
Dmc
col e
Dmd
8549A–CAP–10/08
Dme