SDA5642-6X Siemens, SDA5642-6X Datasheet - Page 10

• Manufacturer Part Number: SDA5642-6X
• Description: VPS-Decoder
• Manufacturer: Siemens

Semiconductor Group
2.2.3
For writing to the VPS decoder, the following format has to be used:
Start
Description of Data Transfer (Write Mode)
Step1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
The write mode is used to set the I
operating mode:
Control Register:
Bit Number: 7
Default: All bits are set to 0 on power-up.
The bits T4 through T7 are used for test purposes and must not be changed for normal
operation by user software! (0 = normal operation)
You may write 00 H , 01 H , 02 H , 03 H , 04 H , 05 H , 06 H , 07 H , 08 H , 09 H , 0A H , 0B H , 0C H ,
0D H , 0E H , 0F H to the register without efect. This enables the SDA 5642-6 to be used
for VPS decoding instead of the SDA 5050 or SDA 5649 without software problems.
Chipaddress and Write Mode AS
Write Mode
In order to start a data transfer the master generates a Start Condition on the
bus by pulling the SDA line low while the SCL line is held high.
The bus master puts the chip address on the SDA line during the next eight
SCL pulses.
The master releases the SDA line during the ninth clock pulse. Thus the slave
can generate an acknowledge (AS) by pulling the SDA line to a low level.
The controller transmits the data byte to set the Control register
The slave acknowledges the reception of the byte.
The master concludes the data communication by generating a Stop
Condition.
T7
6
T6
5
T5
2
C-Bus control register which determines the
4
T4
10
Byte to set Control Register
3
T3
2
T2
1
T1
SDA 5642-6/X
AS Stop
0
T0
02.97