STW5098_07 datasheet(19/86 Pages) STMICROELECTRONICS

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Functional description

STw5098

18/85

4.3

Device programming

STw5098 can be programmed by writing Control Registers with SPI or I2C compatible

control interface (both slave). The interface is always active, there is no need to have the

master clock running to program the device registers. The control interfaces of each entity

can be operated independently either in SPI or I2C modes.

The choice between the two interfaces for each entity is done via their input pins 1CMOD

and 2CMOD (CMOD):

CMOD connected to GND: I2C compatible mode selected

The device address is selected with AS pin:

When this mode is selected control registers are accessed through pins:

SCLK (clock)

SDA (serial data out/in, open drain)

CMOD connected to VCCIO: SPI compatible mode selected

When this mode is selected control registers are accessed through:

AS/CSB (chip select, active low)

SCLK (clock)

SDIN (serial data in)

AD_OCK or DA_OCK or IRQ (serial data out, if selected)

Device Programming: I2C. The I2C Control Interface timing is shown in

Section 6.1 on

page 50. The interface has an internal counter that keeps the current address of the control

loaded with the data of the

increased after each data byte read or write. It is possible to access the interface in 2

modes: single-byte mode in which the address and data of a single register are specified,

and multi-byte mode in which the address of the first register to be written or read is

specified and all the following bytes exchanged are the data of successive registers starting

from the one specified (in multi-byte mode the internal address counter restart from register

0 after the last register 36). Using the multi-byte mode it is possible to write or read all the

registers with a single access to the device on the I2C bus. This applies to both entities of

the device.

Device Programming: SPI. The SPI Control Interface timing is shown in section

Section 6.2 on page 51. Bits SPIOSEL (SPI Output Select) in CR33 control the out pin

selection for serial data out (none, AD_OCK, DA_OCK or IRQ), while bit SPIOHIZ=1 in

CR33 selects the high impedance state of serial data out pin when idle. The first bit sent on

SDIN, after AS/CSB falling edge, sets the interface for writing (SDIN=1) or reading

(SDIN=0), then a 7-bit Control Register address follows.

If the interface is set for writing then the last 8 bits on SDIN are written in the control register.

If the interface is set for reading then after the 7 bit address STw5098 sends out 8 bits data

on the pin selected with bits SPIOSEL in CR33, while bits present at SDIN pin are ignored.

If SPIOSEL=00 (no out pin selected) the reading access on SPI interface can still be useful

to clear the IRQ event bits in CR32.

AS/CSB connected to GND:

chip address 00110101(35hex) for reading, 00110100 (34hex) for writing

AS/CSB connected to VCCIO:

chip address 00110111(37hex) for reading, 00110110 (36hex) for writing

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