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Freescale Semiconductor
Application Note
© 2014 Freescale Semiconductor, Inc. All rights reserved.
PROFIBUS is a fieldbus protocol defined in the IEC 61158
standards. It uses RS-485 UART for the physical layer at
rates up to 12 Mbaud. The layer 2 MAC is typically
implemented in an ASIC. However, on the QUICC Engine
microcode assumes this function for both PROFIBUS
master and slave modes.
This application note explains the baud rate clocking,
physical layer connectivity, initialization, configuration, and
control of a UCC UART programmed for the PROFIBUS
mode of operation. It is aimed at hardware and low-level
software developers and is relevant for the following
devices:
• QorIQ P1012, P1016, P1021, and P1025
• PowerQUICC MPC8306 and MPC8309
• QorIQ Layerscape LS1020A & LS1021A
This application note is supplemental to the PROFIBUS
microcode user’s manual in the QEIWRM specification and
the data sheet of the target device. It is recommended that
these instructions are followed in order to develop a
conformant PROFIBUS master or slave on applicable QorIQ
and PowerQUICC devices.
Document Number: AN4877
Rev. 1, 12/2014
Contents
1. Baud rate generation and timers . . . . . . . . . . . . . . . . . 2
2. Using multiple peripherals in PROFIBUS mode . . . . 6
3. UCC UART physical layer recommendations . . . . . . 8
4. Enabling idle transmit mode . . . . . . . . . . . . . . . . . . . 14
5. Memory resources . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6. TWR-P1025 disclaimer . . . . . . . . . . . . . . . . . . . . . . 19
A. GPIO configuration example code . . . . . . . . . . . . . . 20
PROFIBUS
on the QUICC Engine Block
