pca9549bs NXP Semiconductors, pca9549bs Datasheet - Page 8

• Manufacturer Part Number: pca9549bs
• Description: Octal Bus Switch With Individually I2c-bus Controlled Enables
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7. Characteristics of the I
PCA9549_1
Product data sheet
7.1.1 START and STOP conditions
7.1 Bit transfer
7.2 System configuration
The I
lines are a serial data line (SDA) and a serial clock line (SCL). Both lines must be
connected to a positive supply via a pull-up resistor. Data transfer may be initiated only
when the bus is not busy.
One data bit is transferred during each clock pulse. The data on the SDA line must remain
stable during the HIGH period of the clock pulse as changes in the data line at this time
will be interpreted as control signals (see
Both data and clock lines remain HIGH when the bus is not busy. A HIGH-to-LOW
transition of the data line while the clock is HIGH is defined as the START condition (S).
A LOW-to-HIGH transition of the data line while the clock is HIGH is defined as the STOP
condition (P) (see
A device generating a message is a ‘transmitter’; a device receiving is the ‘receiver’. The
device that controls the message is the ‘master’ and the devices which are controlled by
the master are the ‘slaves’ (see
Fig 8. Bit transfer
Fig 9. Definition of START and STOP conditions
2
C-bus is for 2-way, 2-line communication between different ICs or modules. The two
SDA
SCL
START condition
2
SDA
SCL
Figure
C-bus
S
Rev. 01 — 11 July 2006
Octal bus switch with individually I
9).
Figure
data valid
data line
stable;
10).
Figure
allowed
change
of data
8).
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
2
C-bus controlled enables
STOP condition
mba607
P
PCA9549
mba608
SDA
SCL
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