1.4.3.3
I
2C (see page 331)
The Inter-Integrated Circuit (I
2C) bus provides bi-directional data transfer through a two-wire design
(a serial data line SDA and a serial clock line SCL).
The I
2C bus interfaces to external I2C devices such as serial memory (RAMs and ROMs), networking
devices, LCDs, tone generators, and so on. The I
2C bus may also be used for system testing and
diagnostic purposes in product development and manufacture.
The LM3S8730 controller includes one I
2C module that provides the ability to communicate to other
IC devices over an I
2C bus. The I2C bus supports devices that can both transmit and receive (write
and read) data.
Devices on the I
2C bus can be designated as either a master or a slave. The I2C module supports
both sending and receiving data as either a master or a slave, and also supports the simultaneous
operation as both a master and a slave. The four I
2C modes are: Master Transmit, Master Receive,
Slave Transmit, and Slave Receive.
A Stellaris
® I2C module can operate at two speeds: Standard (100 Kbps) and Fast (400 Kbps).
Both the I
2C master and slave can generate interrupts. The I2C master generates interrupts when
a transmit or receive operation completes (or aborts due to an error). The I
2C slave generates
interrupts when data has been sent or requested by a master.
1.4.3.4
Controller Area Network (see page 366)
Controller Area Network (CAN) is a multicast shared serial-bus standard for connecting electronic
control units (ECUs). CAN was specifically designed to be robust in electromagnetically noisy
environments and can utilize a differential balanced line like RS-485 or a more robust twisted-pair
wire. Originally created for automotive purposes, now it is used in many embedded control
applications (for example, industrial or medical). Bit rates up to 1Mb/s are possible at network lengths
below 40 meters. Decreased bit rates allow longer network distances (for example, 125 Kb/s at
500m).
A transmitter sends a message to all CAN nodes (broadcasting). Each node decides on the basis
of the identifier received whether it should process the message. The identifier also determines the
priority that the message enjoys in competition for bus access. Each CAN message can transmit
from 0 to 8 bytes of user information. The LM3S8730 includes one CAN units.
1.4.3.5
Ethernet Controller (see page 407)
Ethernet is a frame-based computer networking technology for local area networks (LANs). Ethernet
has been standardized as IEEE 802.3. It defines a number of wiring and signaling standards for the
physical layer, two means of network access at the Media Access Control (MAC)/Data Link Layer,
and a common addressing format.
The Stellaris® Ethernet Controller consists of a fully integrated media access controller (MAC) and
network physical (PHY) interface device. The Ethernet Controller conforms to IEEE 802.3
specifications and fully supports 10BASE-T and 100BASE-TX standards. In addition, the Ethernet
Controller supports automatic MDI/MDI-X cross-over correction.
1.4.4
System Peripherals
1.4.4.1
Programmable GPIOs (see page 154)
General-purpose input/output (GPIO) pins offer flexibility for a variety of connections.
29
September 02, 2007
Preliminary
LM3S8730 Microcontroller
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