Definition of the SPI-Bus

The SPI-Bus has 4 lines at minimum (max. 7 lines):

• CLK: Clock frequence - at each clock the data transmission is carried out.
• CS0-CS3: Selection of the connected sensors.
• MOSI (Master Out Slave In): Data line of the master commands
• MISO (Master In Slave Out): Data line of the sensor signals.

After the CS line has selected the desired sensor, the master data and the sensor data will be transmitted bit for bit and clock by clock to the bus.

Example of a SPI-Bus communication with one CS:

The following variations of the settings of the Clk-Signal results in 4 BUS operating systems:

CLK-Phase		CLK-Polarity		Settings Simulyzer
Data transmission by rising edge.		Idle = 0
Data transmission by rising edge.			Idle=1
	Data transmission by falling edge.	Idle=0
	Data transmission by falling edge.		Idle=1

The following parameters are necessary for further characteristics of the SPI-Bus:

The parameters are filled with predefined values, that means settings are only available if the desired values different from the predefined values.

• ESettings of the clk signal (Predefined value: Clockphase=0)
• CLK-frequency (Predefined value: SpiClockRate=2)
• Protocol format (Predefined value: SpiMode=Inframe)
• CS line definition (Predefined value: CSMask=1)
• Error detection (Predefined value: Parity=Off)
• Delay time of CS actived and first clock (Predefined value: FirstClockDelay=0)
• Delay time of CS deactived and last clock (Predefined value: LastClockDelay=0)
• Delay time of CLK and MOSI signal (Predefined value: MosiClockDelay=0)