AT91R40807-33AI Atmel, AT91R40807-33AI Datasheet - Page 24

• Manufacturer Part Number: AT91R40807-33AI
• Description: IC ARM7 MCU 176 TQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91R40807-33AI

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, UART/USART
• Peripherals: WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 136K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

Byte Write or Byte Select
Access
24
AT91X40 Series
Each chip select with a 16-bit data bus can operate with one of two different types of
write access:
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This option is controlled by the BAT field in the EBI_CSR (Chip Select Register) for the
corresponding chip select.
Byte Write Access is used to connect 2 x 8-bit devices as a 16-bit memory page.
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Figure 11 shows how to connect two 512K x 8-bit devices in parallel on NCS2.
Figure 11. Memory Connection for 2 x 8-bit Data Busses
Byte Write Access supports two byte write and a single read signal.
Byte Select Access selects upper and/or lower byte with two byte select lines, and
separate read and write signals.
The signal A0/NLB is not used.
The signal NWR1/NUB is used as NWR1 and enables upper byte writes.
The signal NWR0/NWE is used as NWR0 and enables lower byte writes.
The signal NRD/NOE is used as NRD and enables half-word and byte reads.
EBI
D8 - D15
A1 - A19
D0 - D7
NWR1
NWR0
NCS2
NRD
A0
D0 - D7
A0 - A18
Write Enable
Read Enable
Memory Enable
D8 - D15
A0 - A18
Write Enable
Read Enable
Memory Enable
1354D–ATARM–08/02