CD1865 Datasheet, PDF (112/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

CD1865 — Intelligent Eight-Channel Communications Controller
9.4.1
Enable Register
Register Name:
Register Description: Service Request Enable Register
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
DSR
CD
CTS
RxD
Bit 3
RxSC
Bit 2
TxRdy
8-Bit Hex Address: $02
Intel Hex Address: $04
Motorola Hex Address: $05
Bit 1
Bit 0
TxMpty
NNDT
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
9.4.2
A ‘1’ in each bit position enables service request generation for the associated cause.
Description
Data-Set-Ready (DSR) Service Request: When enabled, generates a Modem-Change Service Request on
the selected level changes of the DSR Input.
Carrier Detect (CD) Service Request: When enabled, generates a Modem-Change Service Request on the
selected level changes of the CD Input.
Clear-To-Send (CTS) Service Request: When enabled, generates a Modem-Change Service Request on
the selected level changes of the CTS Input.
Receive Data Service Request: When enabled, the Receive Data Service Request is generated for receive
data and Receive Exceptions.
Receive Special Character (RxSC) Service Request: When enabled, the Receive Data Exception Service
Request is generated when a received character matches one of the four user-defined special characters.
When disabled, Receive Exceptions are generated for error conditions and time-outs only. If flow-control
transparency is set, flow-control characters are stripped, and no Receive Special Character Exceptions
occurs.
Transmit Ready (TxRdy) Service Request: When enabled, the transmitter generates a service request
when the Transmit FIFO becomes empty. Set this bit when first beginning transmission on a channel, and
before attempting to write data to the Transmit FIFO. Enabling the service request causes an immediate
Transmit Service Request, allowing it to write data into the Transmit FIFO in the usual manner. This bit may be
set and cleared as needed to regulate the assertion of Transmit Data Service Requests on each channel. This
technique is preferred over disabling the transmitter.
Transmitter Empty (TxMpty) Service Request: When enabled, a service request is generated when the
Transmit FIFO, the Transmit Holding register, and the Transmit Shift register are all empty. This mode is
provided to allow the host to determine when all bits are sent and it is safe to alter a channel’s configuration.
No New Data Time-out (NNDT) Service Request: When enabled, a Receive Exception Service Request is
generated after the completion of data transfer from the CD1865 to the host. This feature assists in buffer
management by providing a notice of a gap in the Receive Data Stream longer than the time-out period.
Channel Command Register
Register Name:
Register Description: Channel Command Register
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
RESET CHAN COR CHNG SEND SP CH CHAN CTL
Bit 3
D3
Bit 2
D2
8-Bit Hex Address: $01
Intel Hex Address: $02
Motorola Hex Address: $03
Bit 1
Bit 0
D1
D0
112
Datasheet