CD2481 Datasheet, PDF (134/222 Pages) Intel Corporation – Programmable Four-Channel Communications Controller

CD2481 — Programmable Four-Channel Communications Controller
COR6 — Bisync Mode
Register Name: COR6
Register Description: Channel Option 6
Default Value: x’00
Access: Byte Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Special Frame Termination Character
Intel Hex Address: x’1B
Motorola Hex Address: x’18
Bit 1
Bit 0
In Bisynchronous mode, this register provides a frame-termination method for a receive character
other than the one already defined in the bisynchronous specification. When an initialize channel
command in the CCR is processed, COR6 is set to the value of DLE (hex 10); this deactivates the
function because DLE processing is always performed before a match with COR6 is performed.
Following the completion of the initialize channel command, the user can program COR6 to any
character value where frame termination is required.
One use of this might be to terminate non-transparent frames where the termination character has
been corrupted. If the idle line character (hex FF in 8-bit mode, hex 7F in 7-bit mode) is
programmed in COR6 when a normal termination character is corrupted (that is, ETX hex 03 is
changed to hex 07), the BCC is received as data and the idle line condition causes the frame to
terminate. The idle line character is the last character in the frame. No attempt is made to perform a
CRC on the receive data under these conditions.
COR6 — X.21 Mode
Register Name: COR6
Register Description: Channel Option 6
Default Value: x’00
Access: Byte Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
SYN Character
Intel Hex Address: x’1B
Motorola Hex Address: x’18
Bit 2
Bit 1
Bit 0
In X.21 mode, this register contains the character to be used for find character synchronization with
the receive data stream. When the initialize channel command in the CCR is processed, COR6 is
set to the value ASCII SYN (hex 16). If the user requires a different synchronization character,
COR6 can be loaded with that character after the initialize channel command completes, as in the
following sequence:
1. Issue initialize channel command.
2. Wait for command to complete (CCR returns to hex 00).
3. Reprogram COR6 to the desired character.
4. Issue receive enable command by CCR.
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Datasheet