34-2
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part IV. Communications Processor Module
The I
2
C receiver and transmitter are double-buffered, which corresponds to an effective
two-character FIFO latency. In normal operation, the transmitter shifts the msb (bit 0) out
Þrst. When the I
2
C is not enabled in the I
2
C mode register (I2MOD[EN] = 0), it consumes
little power.
34.1 Features
The following is a list of the I
2
C controllerÕs main features:
¥
Two-signal interface (SDA and SCL)
¥
Support for master and slave I
2
C operation
¥
Multiple-master environment support
¥
Continuous transfer mode for automatic scanning of a peripheral
¥
Supports a maximum clock rate of 2,080 KHz (with a CPM utilization of 25%),
assuming a 100-MHz system clock.
¥
Independent, programmable baud-rate generator
¥
Supports 7-bit I
2
C addressing
¥
Open-drain output signals allow multiple master conÞguration
¥
Local loopback capability for testing
34.2 I
2
C Controller Clocking and Signal Functions
The I
2
C controller can be conÞgured as a master or slave for the serial channel. As a master,
the controllerÕs BRG provides the transfer clock. The I
2
C BRG takes its input from the BRG
clock (BRGCLK), which is generated from the CPM clock; see Section 9.8, ÒSystem Clock
Control Register (SCCR).Ó
SDA and SCL are bidirectional signals connected to a positive supply voltage through an
external pull-up resistor. When the bus is free, both signals are pulled high. The general I
2
C
master/slave conÞguration is shown in Figure 34-2.
Figure 34-2. I
2
C Master/Slave General Configuration
VDD
VDD
Master
Slave
(EEPROM, for example)
SCL
SCL
SDA
SDA
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
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