AT91SAM7S32-AI ATMEL [ATMEL Corporation], AT91SAM7S32-AI Datasheet - Page 247

• Manufacturer Part Number: AT91SAM7S32-AI
• Description: AT91 ARM Thumb-based Microcontrollers
• Manufacturer: ATMEL [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:
• DLYBCT: Delay Between Consecutive Transfers
This field defines the delay between two consecutive transfers with the same peripheral without removing the chip select.
The delay is always inserted after each transfer and before removing the chip select if needed.
When DLYBCT equals zero, no delay between consecutive transfers is inserted and the clock keeps its duty cycle over the
character transfers.
Otherwise, the following equation determines the delay:
If FDIV is 0:
If FDIV is 1:
Note:
6071A–ATARM–28-Oct-04
N = 32
N = 32
N = 32
SPCK Baudrate
Delay Before SPCK
Delay Before SPCK
Delay Between Consecutive Transfers
Delay Between Consecutive Transfers
SPCK Baudrate
=
=
----------------------------- -
-------------- -
SCBR
MCK
N
=
=
MCK
DLYBS
------------------ -
N
---------------------------- -
SCBR
MCK
MCK
DLYBS
=
=
32
----------------------------------- -
32
---------------------------------------------- -
MCK
DLYBCT
N
MCK
DLYBCT
+
---------------- -
2MCK
AT91SAM7S32 Preliminary
SCBR
+
N
------------------------ -
2MCK
SCBR
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