AT91SAM7A1-AU Atmel, AT91SAM7A1-AU Datasheet - Page 34

• Manufacturer Part Number: AT91SAM7A1-AU
• Description: IC ARM7 MCU 32BIT ROMLESS144LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7A1-AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 40MHz
• Connectivity: CAN, EBI/EMI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 49
• Program Memory Type: ROMless
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 144-LQFP
• For Use With: AT91SAM7A1-EK - BOARD EVAL FOR AT91SAM7A1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

10.4.3
10.4.3.1
34
AT91SAM7A1
Wait States
Standard Wait State
Figure 10-10. Write Access
The EBI can automatically insert wait states during the external access cycles. These wait
states are applied within the actual access cycle.
Different types of wait states are possible:
Each chip select line can be programmed to insert one or more wait states during an external
access. This is done by setting the WSE bit in the corresponding AMC_CSRx register. The
number of cycles to insert is programmed in the NWS[2:0] field in the same register.
Wait states are inserted within cycles and delay the read and write access cycles.
The read cycle is delayed one cycle for each wait state programmed. In early mode,
NOE/NRD goes low at the start of the read cycle. In standard mode, this signal goes low at the
half of the first cycle.
Figure 10-11. Read Cycle with One Wait State
• Standard wait states
• Data float wait states
• External wait states
• Wait state with read cycle
NOE/NRD
Address
Address
NWE
NCS
NCS
Address Valid
Address Valid
6048B–ATARM–29-Jun-06