at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 235

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

21.14.4
Register Name:
Access Type:
• READ_MODE:
1: The read operation is controlled by the NRD signal.
0: The read operation is controlled by the NCS signal.
• WRITE_MODE
1: The write operation is controlled by the NWE signal.
0: The write operation is controlled by the NCS signal.
• EXNW_MODE: NWAIT Mode
The NWAIT signal is used to extend the current read or write signal. It is only taken into account during the pulse phase of
the read and write controlling signal. When the use of NWAIT is enabled, at least one cycle hold duration must be pro-
grammed for the read and write controlling signal.
6249D–ATARM–20-Dec-07
• Disabled Mode: The NWAIT input signal is ignored on the corresponding Chip Select.
• Frozen Mode: If asserted, the NWAIT signal freezes the current read or write cycle. After deassertion, the read/write
• Ready Mode: The NWAIT signal indicates the availability of the external device at the end of the pulse of the controlling
cycle is resumed from the point where it was stopped.
read or write signal, to complete the access. If high, the access normally completes. If low, the access is extended until
NWAIT returns high.
– If TDF cycles are programmed, the external bus is marked busy after the rising edge of NRD.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states are inserted after the setup of NRD.
– If TDF cycles are programmed, the external bus is marked busy after the rising edge of NCS.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states are inserted after the setup of NCS.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states will be inserted after the setup of NWE.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states will be inserted after the setup of NCS.
31
23
15
–
–
–
7
–
SMC MODE Register
0
0
1
1
EXNW_MODE
30
22
14
SMC_MODE[0..7]
Read/Write
–
–
–
6
–
0
1
0
1
29
21
13
–
5
EXNW_MODE
DBW
PS
TDF_MODE
NWAIT Mode
Disabled
Reserved
Frozen Mode
Ready Mode
28
20
12
4
27
19
11
–
–
3
–
AT91SAM9263 Preliminary
26
18
10
–
–
2
–
TDF_CYCLES
WRITE_MODE
25
17
–
9
–
1
READ_MODE
PMEN
BAT
24
16
8
0
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