SAM9N12 Datasheet, PDF (670/1137 Pages) ATMEL Corporation – The ARM926EJ-S based SAM9CN12 features the frequently requested combination of user...

• BITS: Bits Per Transfer
(See the ^(Note:) below the register table; Section 36.8.9 “SPI Chip Select Register” on page 669.)
The BITS field determines the number of data bits transferred. Reserved values should not be used.
Value
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Name
8_BIT
9_BIT
10_BIT
11_BIT
12_BIT
13_BIT
14_BIT
15_BIT
16_BIT
–
–
–
–
–
–
–
Description
8 bits for transfer
9 bits for transfer
10 bits for transfer
11 bits for transfer
12 bits for transfer
13 bits for transfer
14 bits for transfer
15 bits for transfer
16 bits for transfer
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
• 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:
SPCK Baudrate = -^M------^C----^K---
SCBR
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.
Note: If one of the SCBR fields inSPI_CSRx is set to 1, the other SCBR fields in SPI_CSRx must be set to 1 as well, if they are
required to process transfers. If they are not used to transfer data, they can be set at any value.
• 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:
Delay Before SPCK = ^D-----^L----^Y----^B----^S-
MCK
670 SAM9N12/SAM9CN11/SAM9CN12
11063G–ATARM–09-Oct-12