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21020285 D User’s Guide
Chapter 2 Hardware Essentials
Page 2 - 6 Hardware Ports: General
Hardware
Ports: General
There are four ports that are used to communicate with the RF3880 adapter:
Address Buffer Port; Channel Attention Port; Status Port; and Reset Port. The
address and function of each port is described in this section.
Hardware Port
Addresses
Each of the Hardware ports can be addressed as an offset from the base address,
(which is set with jumpers on the board). Further, all ports can be accessed in
16-bit mode. To address a specific port you must add the correct offset to the
base address value. The offset values for the RF3880 hardware ports are
described in the figure below.
Example Port Addresses - Using the factory set Base Address for the
RF3880, EE00H, the Hardware Port Addresses would be:
Address Port = EE00H
Channel Attention Port = EE08H
Status Port = EE10H
Reset Port = EE18H
The table above also indicates how each port can be accessed by the Host: read
or write.
Overview of
the Ports
An overview of the operation of all of the Hardware Ports is provided next. The
overview is followed by a detailed description of each Hardware Port that
focuses on the rules of operation.
Address Buffer Port - This port is instrumental in setting up the RF3880
adapter I/O operation. With it you can do two things:
1. Set system bus transfer characteristics such as bus width and byte/word
swapping for subsequent operations. Usually this is done only with the
first command sent to the board, when you are initializing the board for
operation in your system.
2. Pass the address of a Single Command Structure to the adapter. Any
time you wish to issue a Single Command, you must use the Address
Buffer Port to pass the address structure. Most often, the first Single
Command executed contains a command to Start Command List. This
function of the port is only used when issuing a Single Command.
Port Address Offset Host Read or Write
Address Buffer 00H Write
Channel Attention 08H Write
Status 10H Read
Reset 18H Write
Table 5: Hardware Port Addresses