47.7.9 QSPI Serial Clock Register

This register can only be written if bit WPEN is cleared in the QSPI Write Protection Mode Register.

Name:	QSPI_SCR
Offset:	0x20
Reset:	0x00000000
Property:	Read/Write


Bit	31	30	29	28	27	26	25	24

Access
Reset


Bit	23	22	21	20	19	18	17	16
	DLYBS[7:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	15	14	13	12	11	10	9	8
	SCBR[7:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0


Bit	7	6	5	4	3	2	1	0
							CPHA	CPOL
Access							R/W	R/W
Reset							0	0

Bits 23:16 – DLYBS[7:0] Delay Before QSCK

This field defines the delay from QCS valid to the first valid QSCK transition.

When DLYBS equals zero, the QCS valid to QSCK transition is 1/2 the QSCK clock period.

Otherwise, the following equation determines the delay:

DLYBS = Delay Before QSCK × f_{peripheral clock}

Bits 15:8 – SCBR[7:0] Serial Clock Baud Rate

The QSPI uses a modulus counter to derive the QSCK baud rate from the peripheral clock. The baud rate is selected by writing a value from 0 to 255 in the SCBR field. The following equation determines the QSCK baud rate:

SCBR = (f_{peripheral clock} / QSCK Baudrate) - 1

Bit 1 – CPHA Clock Phase

CPHA determines which edge of QSCK causes data to change and which edge causes data to be captured. CPHA is used with CPOL to produce the required clock/data relationship between host and client devices.

Value	Description
0	Data is captured on the leading edge of QSCK and changed on the following edge of QSCK.
1	Data is changed on the leading edge of QSCK and captured on the following edge of QSCK (only available in SPI mode, QSPI_MR.SMM=0).

Bit 0 – CPOL Clock Polarity

CPOL is used to determine the inactive state value of the serial clock (QSCK). It is used with CPHA to produce the required clock/data relationship between host and client devices.

Value	Description
0	The inactive state value of QSCK is logic level zero.
1	The inactive state value of QSCK is logic level one (only available in SPI mode, QSPI_MR.SMM=0).