CD2481 Datasheet, PDF (132/222 Pages) Intel Corporation – Programmable Four-Channel Communications Controller

CD2481 — Programmable Four-Channel Communications Controller
Bit 4
Number of characters in FIFO
0 Less than or equal to threshold
0 Greater than threshold
1 Less than or equal to threshold
1 Greater than threshold
CD2481 Action
DTR asserted
DTR deasserted
XON transmitted
XOFF transmitted
Note: Do not use the STCR (Special Transmit Command register) to send XON and XOFF characters
while using automatic in-band flow control.
Bits 3:0
Receive flow control FIFO threshold
These four bits define the threshold for automatic flow control activation based on
the contents of the receive FIFO. A threshold value of zero disables this function and
the setting of bit 4 is ignored. Bit 4 determines whether the out-of-band (DTR pin)
or the in-band (XOFF/XON characters) is used to stop the flow of incoming data
from the remote transmitter.
When the number of characters in the FIFO exceeds this threshold, the DTR pin
deasserts or an XOFF character is transmitted. When the number of characters in the
FIFO is less than or equal to the threshold, the DTR asserts or and XON is transmit-
ted.
9.2.7
Channel Option Register 6 (COR6)
COR6 — Async Mode
Register Name: COR6
Register Description: Channel Option Register 6
Default Value: x’00
Access: Byte Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
IgnCR
ICRNL
INLCF
IgnBrk
Bit 3
NBrkInt
Intel Hex Address: x’1B
Motorola Hex Address: x’18
Bit 2
ParMrk
Bit 1
INPCK
Bit 0
ParInt
CR is defined as 0D hex, NL as 0A hex, and NULL as 00 hex.
Bits 7:5
These three bits are used to enable translation of received CR/NL characters as fol-
lows:
IgnCr
0
0
0
0
1
ICrRNL
0
0
1
1
0
INLCR
0
1
0
1
0
No special action on CR and NL
NL translated to CR
CR translated to NL
CR translated to NL and NL translated
to CR
CR discarded
132
Datasheet