TDA7415CB Datasheet, PDF (32/50 Pages) STMicroelectronics – Car radio multimedia signal processor

Digital interface
6
Digital interface
TDA7415CB
The TDA7415CB digital interface supports two different protocols: SPI and I²C. To select the
I²C-mode the SEL-pin has to be tied to the system supply by means of a 68k -resistor. If the
voltage at the SEL-pin falls below 5.5V, the interface switches to SPI-mode. Consequently,
the interface is able to work with a microprocessor either supplied by a 3.3V or a 5V power
supply. The SPI-mode has to be set and remain static before the device leaves the reset
state caused by power-on reset (POR).
For details of both protocols refer to the programming section.
6.1
Interface in SPI -mode
● Interface protocol
The SPI interface protocol comprises:
– A sub-address (SAx) and
A sequence of n data bytes (Dy); each consisting of 8 bits.
A negative going edge at SEL enables the interface receiving data. The interface accepts
both a positive (Cpol=1, Cpha=1; SPI-mode 0) as well as a negative (Cpol=0, Cpha=0; SPI-
mode 3) clocking scheme. However, the data transmitted has to be valid on the rising
edges of the serial clock SCL.
Figure 24. Switching characteristics (SPI-mode):
Figure 25. Interface in SPI -mode diagram
SEL
SCL
SDA
Tscl
Tsu
Thld
Twh Twl Trel Tsh
SAx,Dy
AC00507
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