mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 768

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

Communication Processor Module
When a station needs to transmit, it checks for activity on the LAN and when the LAN
becomes silent for a specified period, the station starts transmitting. At that time, the station
continually checks for collision on the LAN and if one is found, the station forces a jam of all
ones on its frame and stops transmitting. Collisions usually occur close to the beginning of
a frame. The station waits a random period of time, called a backoff, before trying to transmit
again. Once the backoff is complete, the station waits for silence on the LAN and then
begins retransmission on the LAN, which is called a retry. If the frame is not successfully
transmitted within 15 retries, an error occurs. The 10Mbps Ethernet provides 0.8 s per byte.
The preamble plus start frame delimiter is transmitted in 6.4 s. The minimum interframe gap
is 9.6 s and the slot time is 52 s. Therefore, you must operate the MPC823 at a minimum
frequency of 20MHz to implement Ethernet.
16.9.22.1 FEATURES. The following list summarizes the main features of a serial
communication controller in Ethernet mode:
• Performs MAC layer functions of Ethernet and IEEE 802.3
• Full-duplex operation support
• Performs framing functions
• Full collision support
• Maximum 10Mbps (10BASE-T) bit rate
• Back-to-back frame reception
• Detection of receive frames that are too long
• Multibuffer data structure
• Supports 48-bit addresses in three modes
• Up to eight parallel I/O pins can be sampled and appended to any frame
• Heartbeat indication
• Transmitter network management and diagnostics
• Receiver network management and diagnostics
• Error counters
• Internal and external loopback mode
Freescale Semiconductor, Inc.
For More Information On This Product,
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
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