TLE7232G Datasheet, PDF (25/36 Pages) Infineon Technologies AG – SPI Driver for Enhanced Relay Control

SPI Driver for Enhanced Relay Control
SPIDER - TLE 7232G
Serial Peripheral Interface (SPI)
4.4
Serial Peripheral Interface (SPI)
The diagnosis and control interface is based on a serial peripheral interface (SPI).
The SPI is a full duplex synchronous serial slave interface, which uses four lines: SO, SI,
SCLK and CS. Data is transferred by the lines SI and SO at the data rate given by SCLK.
The falling edge of CS indicates the beginning of a data access. Data is sampled in on
line SI at the falling edge of SCLK and shifted out on line SO at the rising edge of SCLK.
Each access must be terminated by a rising edge of CS. A modulo 8 counter ensures
that data is taken only, when a multiple of 8 bit has been transferred. The interface
provides daisy chain capability.
SO
SI
CS
SCLK
MSB 14 13 12 11 10 9
8
7
6
5
4
3
2
1
LSB
MSB 14 13 12 11 10 9
8
7
6
5
4
3
2
1 LSB
time
Figure 10 Serial Peripheral Interface
SPI.emf
The SPI protocol is described in Section 4.4.5. It is reset to the default values after
power-on reset or a low signal at pin RST.
4.4.1 SPI Signal Description
CS - Chip Select: The system micro controller selects the SPIDER - TLE 7232G by
means of the CS pin. Whenever the pin is in low state, data transfer can take place.
When CS is in high state, any signals at the SCLK and SI pins are ignored and SO is
forced into a high impedance state.
CS High to Low transition:
• The diagnosis information is transferred into the shift register.
CS Low to High transition:
• Command decoding is only done, when after the falling edge of CS exactly a multiple
(1, 2, 3, …) of eight SCLK signals have been detected.
• Data from shift register is transferred into the input matrix register.
• The diagnosis flags are cleared.
SCLK - Serial Clock: This input pin clocks the internal shift register. The serial input (SI)
transfers data into the shift register on the falling edge of SCLK while the serial output
Data Sheet
25
V1.0, 2005-09-30