I2C-Interface Philips Semiconductors / NXP Semiconductors, I2C-Interface Datasheet - Page 5

• Manufacturer Part Number: I2C-Interface
• Description: Programming the 12C Interface
• Manufacturer: Philips Semiconductors / NXP Semiconductors

l*C Specific information
should be determined by your destina-
tion. Contrary to what some people may
tell you, the choice of bus and protocol
depends at least as much on the nature
of the system’s software as it does on the
manufacturer’s data sheets.
ripheral interface (SPI) and multidrop
On the hardware side, any added inter-
support is frequently compensated for
pinout of the serial peripherals.
CHOOSlN6 THE PROPER ROUll
the most appropriate bus and protocol.
Here, as with rapid transit, your choice
down the house if they were to occur on
ally be controlled over a much greater
distance by a serial bus. The serial ap-
noise immunity.
nience is a slower transmission rate and,
possibly, the need for added interface
circuitry at higher voltages. Many pr-
ipheral devices, however, are not in con-
stant communication with the CPU and
are not greatly affected by a slower bus.
face circuitry required for serial-bus
by the resulting simplicity and
H
are often often more convenient and less
expensive than parallel buses. Addi-
tionally, a serial interface featuring a
UART or similar intermediary
can also serve to isolate the CPU from
noise and line glitches that might bring
the prczessor bus. Peripherals can usu-
proach offers greater
S
Consider, for example, the serial-pe-
The price you pay for the conve-
aving decided that a serial bus
makes sense for your applica-
tion, your next task is to select
erial data buses are a well-
proven tool in embedded
systems. When you are com-
municating with slow per-
ipheral devices, serial buses
73
resilience and
tighter
chip
bedded Systems Programming, March
called MicroWire, available from Na-
tional Semiconductor in Santa Clara.
Calif., which is fine for use with addres-
sable peripherals, but requires an indi-
vidual chip select for each device ad-
various 805
chips hnds its broadest expression in
leaving it mainly suitable for single-
master multiple-slave situations. (For
more on multidrop, see Jack Woehr’s
article, “Multidrop Processing, ” Em-
proach is to use a three-wire protocol
serial buses. Both buses are popular, but
each exhibits severly constrained per-
formance in large networks. SPI, as em-
bodied in the Motorola 6800 family,
was designed primarily for one-on-one
exchanges between two devices. Simi-
larly, the multidrop approach used in
in the 68HC 11 and various UART
RS485/422 halfduplex transmissions.
Multidrop has no deterministic arbitra-
tion scheme between multiple masters,
1990, pp 58-67-ed.)
The choice of bus
and protocol
depends at least as
much on the
system’s software
as it does on the
manufacturer’s
data sheets.
I
family members as well as
Exploring l*C
A different ap-