CD1865 Datasheet, PDF (113/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

Intelligent Eight-Channel Communications Controller — CD1865
The CCR is a special register used to prompt the CD1865 processor to indicate if any channel
parameters have changed. Bits are set in the CCR to indicate which of several commands to carry
out. The CD1865 processor notes changes in these bits and makes the required adjustments to the
hardware; this process can take from microseconds to milliseconds. Therefore, it is important that
the host CPU waits until the CD1865 processor has finished the current command before issuing
any more commands, or continuing with any operation that the command affects. For example,
after setting the Local Loopback bit in COR2, the host must wait until the command is complete
before resuming transmission. If the host does not wait, characters may not be properly looped
back.
Reset Channel, Channel Option, Send Special Character, and Channel Control commands can be
set through the CCR register. One of the four commands can be selected by setting the appropriate
bit (7:4). The commands can be defined in detail by setting the bit fields (3:0) accordingly. Bit
fields (3:0) are defined differently by each command. The CD1865 indicates completion by
clearing the CCR.
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bits 3:0
Description
Reset Channel Command.
Channel Option Register Command.
Send Special Character(s) Command.
Channel Control Command.
Defined by the type of command being issued; see the following descriptions.
The tables on the following pages define the appropriate setting of the bits according to the
command.
Reset Channel Command
Bit 7
RESET CHAN
Bit 6
0
Bit 5
0
Bit 4
0
Bit 3
0
Bit 2
0
Bit 1
0
Bit 0
TYPE
This is a software reset command. There are two types of reset — Channel Reset (type 0), which
resets only the current channel, and Global Reset (type 1), which resets the entire part to its power-
up condition. When the channel reset command is issued, the CD1865 disables the transmitter and
the receiver and clears the Data and Status FIFOs of the channel. Channel parameters are not
affected by a Channel Reset.
Bit
Bit 7
Bits 6:1
Bit 0
Description
Reset Channel Command, must be a ‘1’.
Not used. Must be a ‘0’.
Reset Type: If the Reset Type bit is a ‘0’, a software reset of the channel is performed. The transmitter and
receiver are disabled, and all FIFOs are cleared (flushed). If the Reset Type bit is a ‘1’, an on-device firmware
initialization of all channels is performed. All channel and global parameters are reset to their power-on reset
condition.
Datasheet
113