000-0046140-111
Page 122 of 169
SLG46140
17.2 Clock polarity and phase
In addition to setting the clock frequency, it is possible to configure the clock polarity and phase with respect to the data. This is
configured by the CPOL and CPHA bits respectively.
shows the SPI timing diagram when CPHA = 0; in this mode data can only be transmitted from serial to parallel, not
from parallel to serial.
shows the SPI timing diagram when CPHA= 1; in this mode data can be transmitted both from
serial to parallel and from parallel to serial.
Figure 73. Timing Diagram showing Clock Polarity and Phase, CPHA = 0
Table 75. CPHA = 0 Timing Characteristics
Parameter
Symbol
Min
Max
Units
SCLK period
t
CP
500
--
ns
SCLK pulse width high
t
CH
250
--
ns
SCLK pulse width low
t
CL
250
--
ns
CSB fall to SCLK first edge setup
t
CSS
250
--
ns
SCLK last edge to CSB rise hold
t
CSH
250
--
ns
CSB pulse width high
t
CSW
500
--
ns
SCLK to SDI hold
t
DIH
100
--
ns
SCLK to SDI setup
t
DIS
50
--
ns
SCLK rise/fall time
t
CKR
--
20
ns
CSB
SCLK (CPOL=0)
t
CSS
t
CP
t
CH
t
CL
t
CSH
t
CSW
t
CSH
SCLK (CPOL=1)
SDI
MSB
Bit[1]
LSB
MSB
LSB
Bit[1]
t
DIS
t
DIH
t
CK
F
t
CK
R