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1745D–ATARM–04-Nov-05
AT91M55800A
Figure 11-4. Memory Connection for 2 x 8-bit Data Busses
Byte-select Access is used to connect 16-bit devices in a memory page.
• The signal A0/NLB is used as NLB and enables the lower byte for both read and write
operations.
• The signal NWR1/NUB is used as NUB and enables the upper byte for both read and write
operations.
• The signal NWR0/NWE is used as NWE and enables writing for byte or half word.
• The signal NRD/NOE is used as NOE and enables reading for byte or half word.
Figure 11-5 shows how to connect a 16-bit device with byte and half-word access (e.g. 16-bit
SRAM) on NCS2.
Figure 11-5. Connection for a 16-bit Data Bus with Byte and Half-word Access
EBI
D0 - D7
D8 - D15
A1 - A19
A0
NWR0
NRD
NCS2
D0 - D7
A0 - A18
Write Enable
Read Enable
Memory Enable
NWR1
D8 - D15
A0 - A18
Write Enable
Read Enable
Memory Enable
EBI
D0 - D7
D8 - D15
A1 - A19
NLB
NWE
NOE
NCS2
D0 - D7
D8 - D15
A0 - A18
Low Byte Enable
Write Enable
Output Enable
Memory Enable
NUB High Byte Enable