SAM7SE32 Atmel Corporation, SAM7SE32 Datasheet - Page 207

• Manufacturer Part Number: SAM7SE32
• Manufacturer: Atmel Corporation

Specifications of SAM7SE32

• Flash (kbytes): 32 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 48 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 88
• Ext Interrupts: 88
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Ssc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 8
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

23.6.4
Figure 23-6. Refresh Cycle Followed by a Read Access
6222F–ATARM–14-Jan-11
D[31:0]
A[12:0]
SDWE
SDCS
SDCK
(input)
RAS
CAS
Row n
col c col d
SDRAM Controller Refresh Cycles
Dnb
Dnc
Dnd
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. A 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 will be 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 will indi-
cate that the device is busy and the ARM BWAIT signal will be asserted. See
t
RP
= 3
t
RC
= 8
SAM7SE512/256/32
Row m
t
RCD
= 3
col a
Figure 23-6
CAS = 2
Dma
below.
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