Hardware Reference Manual
421 Intelligent Serial, 8-Port
1
Introduction
This document describes the operation, design and use of PMC421 Serial Input/Output (I/O) card. With a design
combining available embedded processor technology, and high-density serial components, the PMC421 offers a
distinct advantage over traditional serial I/O cards. The result is a solution suitable for a wide range of
applications, from low speed character I/O to demanding multi channel protocol engines.
1.1 Features
The PMC421 is a powerful and flexible solution to integrate serial data channels to a PCI system. Features
include:
1.1.1 PMC421
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PMC Form Factor
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On-Board CPU to Off-Load Host
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Character Blocking & direct memory access (DMA) for Efficient PCI Utilization
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Baud Rate from 150bps - 1.5Mbps
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Software Selectable RS232, RS422, RS485 (Full Duplex & Half Duplex)
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All Ports Fully Independent
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Custom Firmware Options for Special Purpose Applications
The PMC421 provides a uniquely effective solution for integrating serial I/O requirements into a VMEbus or
CompactPCI system. Implemented on a single PMC card, the PMC421 is fully compatible with current generation
VMEbus and CPCI Single Board Computers, as well as any special purpose processor that includes a PMC
connector. In addition, card edge PCI systems can be accommodated using RAMiX's PMC239 adapter for rapid
prototype and development.
Traditional single and multi-port Serial Interfaces place a high overhead on the host processor by requiring per-
character-attention (i.e., each received and transmitted character generates interrupts and programmed I/O from
the host). Two features of the PMC421 remove this overhead:
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On-card CPU for character blocking/unblocking
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Deep FIFO buffers to avoid data overrun (128 Bytes on each port) plus 4MB
Direct control of the 8 Serial Ports (UART) is provided by the on-board processor, a 32-bit RISC CPU. This
processor includes DMA engines for efficient transfers over the PCI (over 100Mbytes/second). Data is buffered in
the on-card DRAM between transfer to/from the UART interface. In addition to off-loading basic character
manipulation, special data handling routines can readily be added to the local processor. Examples include
encryption/description, special protocol handling, error correction, etc.
The PMC421 also provides several unique Serial I/O features. Each port has individually programmable line
drivers to set any of the most popular signaling types: RS232, RS422 and RS485 (full duplex & half duplex). The
DDC No. Rx-URMH 002 Rev -
Issued 12 November 2002
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