Datasheet

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8.1.2 I
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C Bus Overview
Philips (Philips) at 20 years ago invented a simple two-wire bidirectional serial communication
bus, the bus is called the Inter-I
2
C bus. Currently I
2
C bus has become the industry standard solution
for embedded application, is widely used in a variety of professional-based micro controller,
consumer and telecommunications products, as a control, diagnostics and power management bus.
Multiple matches I
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C bus standard devices can communicate via the same I
2
C bus, without the
need to address decoder.
I
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C bus require only the two signal lines, a serial data line SDA, the other is a serial clock
line SCL. I
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C bus devices generally have their SDA and SCL pins are open-drain (or open
collector) output structure. Therefore, actual use, SDA Figure 4: AM2320 wiring diagram and SCL
signal lines must add pull-up resistors (Rp, Pull-Up Resistor). Value pull-up resistor is generally 3 ~
10 k
Ω
. Therefore, when the bus is idle, the two signal lines remain high, almost no current
consumption; electrical compatibility, and supports a variety of different voltage logic device
interfaces; may be directly connected between the two buses, not require additional conversion
circuitry to support a variety of communication more from a major is the most common means of
communication. It also supports dual-host communication, multi host communication and
broadcast mode, etc.
I
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C typical configuration shown in Figure 5.
Figure 5: I
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C typical configuration
8.1.3 I
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C bus protocol specification
◎I
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C Bus Definition of Terms
I
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C bus connection via the serial data (SDA) and serial clock (SCL) lines on the bus, so that
each device to transmit information between the device has a unique address recognition, and can be
used as a transmitter or receiver (the device's functions decision), the device when performing data
transfers can also be seen as a master or slave, the master is initialized data transmission device
allows the transmission bus and generates a clock signal. At this time, any device addressed is
considered a slave. I
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C bus terms are defined in detail in Table 5.
◎I
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C-bus transfer rate
I
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C bus communication rate controlled by the host, to fast to slow. However, the maximum rate