ST92185B STMicroelectronics, ST92185B Datasheet - Page 146

• Manufacturer Part Number: ST92185B
• Description: 16k/24k/32k Rom Hcmos Mcu With On-screen-display
• Manufacturer: STMicroelectronics

ST92185B - SERIAL PERIPHERAL INTERFACE (SPI)
SERIAL PERIPHERAL INTERFACE (Cont’d)
Table 28. Typical I
Figure 90. SPI Data and Clock Timing (for I2C protocol)
n
146/178
SDA
SCL
CONDITION
ACKNOWLEDGE
TRANSMISSION
START
INITIALIZE
START
Phase
STOP
1
2
C-bus Sequences
2
1st BYTE
SPICR.CPOL, CPHA = 0, 0
SPICR.SPEN = 0
SPICR.BMS = 1
SCK pin set as AF output
SDI pin set as input
Set SDO port bit to 1
SDO pin set as output
Open Drain
Set SDO port bit to 0
SPICR.SPEN = 1
SDO pin as Alternate Func-
tion output load data into
SPIDR
SPICR.SPEN = 0
Poll SDA line
Set SDA line
SPICR.SPEN = 1
SDO pin set as output
Open Drain
SPICR.SPEN = 0
Set SDO port bit to 1
FOR ACKNOWLEDGEMENT
DRIVEN BY SOFTWARE
Software
8
CLOCK PULSE
AcK
9
SCK, SDO in HI-Z
SCL, SDA = 1, 1
SDA = 0, SCL = 1
interrupt request
SCL = 0
Start transmission
Interrupt request at end of
byte transmission
SCK, SDO in HI-Z
SCL, SDA = 1
SCL = 0
SDA = 1
interrupt request
Hardware
1
2
n BYTE
th
FOR ACKNOWLEDGEMENT
Set polarity and phase
SPI disable
START/STOP interrupt
Enable
START condition
receiver START detection
Managed by interrupt rou-
tine load FFh when receiv-
ing end of transmission
detection
SPI disable
only if transmitting
only if receiving
only if transmitting
STOP condition
8
CLOCK PULSE
DRIVEN BY SW
AcK
Notes
9
CONDITION
VR000188
STOP