Philips CEM2000/00, Service Manual

Page: 29 / 72

PT7313E
V1.0 5 February 2010
CONTROL BUS SPECIFICATION
BUS INTERFACE
All functions of the PT7313E are controlled by the I
2
C interface, the interface is consisting by SDA and SCL pins. Detail
protocol of the I
2
C bus will discuss on the next section. It should be noted that the bus level pull-up resistors connected to
the PT7313E positive supply voltage may required in some application especially the MCU output high level is no
enough.
DATA VALIDITY
A data on the SDA Line is considered valid and stable only when the SCL Signal is in HIGH State. The HIGH and LOW
State of the SDA Line can only change when the SCL signal is LOW. Please refer to the figure below.
START AND STOP CONDITIONS
A Start Condition is activated when
1) The SCL is set to HIGH and
2) SDA shifts from HIGH to LOW State.
The Stop Condition is activated when
1) SCL is set to HIGH and
2) SDA shifts from LOW to HIGH State. Please refer to the timing diagram below..
BYTE FORMAT
Every byte transmitted to the SDA Line consists of 8 bits. Each byte must be followed by an Acknowledge Bit. The MSB
is first transmitted.
P rinceton Technology Corp
.
ANGUS ELECTRONICS CO., LTD
Tel: (852) 2345 0540 Fax: (852) 2345 9948 Web Site: www.angus.com.hk