at91cap7e ATMEL Corporation, at91cap7e Datasheet - Page 341

• Manufacturer Part Number: at91cap7e
• Description: Customizable Microcontroller
• Manufacturer: ATMEL Corporation

• SCBR: Serial Clock Baud Rate
In Master Mode, the SPI Interface uses a modulus counter to derive the SPCK baud rate from the Master Clock MCK. The
Baud rate is selected by writing a value from 1 to 255 in the SCBR field. The following equations determine the SPCK baud
rate:
If FDIV is 0:
If FDIV is 1:
Note:
Programming the SCBR field at 0 is forbidden. Triggering a transfer while SCBR is at 0 can lead to unpredictable results.
At reset, SCBR is 0 and the user has to program it at a valid value before performing the first transfer.
• DLYBS: Delay Before SPCK
This field defines the delay from NPCS valid to the first valid SPCK transition.
When DLYBS equals zero, the NPCS valid to SPCK transition is 1/2 the SPCK clock period.
Otherwise, the following equations determine the delay:
If FDIV is 0:
If FDIV is 1:
Note:
8549A–CAP–10/08
N = 32
N = 32
SPCK Baudrate
Delay Before SPCK
Delay Before SPCK
Delay Before SPCK
SPCK Baudrate
SPCK Baudrate
BITS
1010
1011
1100
1101
1110
1111
=
=
=
------------------------------ -
(
-------------- -
SCBR
-------------- -
SCBR
N
MCK
MCK
=
=
=
×
MCK
N
----------------------------- -
DLYBS
------------------ -
DLYBS
------------------ -
MCK
MCK
SCBR
×
MCK
DLYBS
)
Bits Per Transfer
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
AT91CAP7E
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