Spi modes – Cypress CY14B101Q3 User Manual
Page 6
PRELIMINARY
CY14B101Q1
CY14B101Q2
CY14B101Q3
Document #: 001-50091 Rev. *A
Page 6 of 22
SPI Modes
CY14B101Q1/CY14B101Q2/CY14B101Q3 may be driven by a
microcontroller with its SPI peripheral running in either of the
following two modes:
■
SPI Mode 0 (CPOL=0, CPHA=0)
■
SPI Mode 3 (CPOL=1, CPHA=1)
For both these modes, input data is latched-in on the rising edge
of Serial Clock (SCK) starting from the first rising edge after CS
goes active. If the clock starts from a HIGH state (in mode 3), the
first rising edge, after the clock toggles, is considered. The output
data is available on the falling edge of Serial Clock (SCK).
The two SPI modes are shown in
status of clock when the bus master is in Standby mode and not
transferring data is:
■
SCK remains at 0 for Mode 0
■
SCK remains at 1 for Mode 3
CPOL and CPHA bits must be set in the SPI controller for either
Mode 0 or Mode 3. The device detects the SPI mode from the
status of SCK pin when the device is selected by bringing the CS
pin LOW. If SCK pin is LOW when device is selected, SPI Mode
0 is assumed and if SCK pin is HIGH, it works in SPI Mode 3.
Figure 4. System Configuration Using SPI nvSRAM
x
Q
1
0
1
B
4
1
Y
C
x
Q
1
0
1
B
4
1
Y
C
u C o n tr o lle r
S C K
M O S I
M IS O
S I
S O
O
S
I
S
K
C
S
S C K
C S
H O L D
H O L D
C S
C S 1
C S 2
H O L D 1
H O L D 2
Figure 5. SPI Mode 0
LSB
MSB
7
6
5
4
3
2
1
0
CS
SCK
SI
0 1
2 3
4 5 6 7
Figure 6. SPI Mode 3
CS
SCK
SI
7
6
5
4
3
2
1
0
LSB
MSB
0
1
2
3
4
5
6
7