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MC68302 Applications
D-36
MC68302 USER’S MANUAL
MOTOROLA
D.6.8 SCC Configuration
SCC1 will be set according the rate adaptation protocol implemented. If V.120 is used, the
protocol should be set to HDLC. If V.110 is used, program SCC1 to V.110 (configured under
the DDCMP mode). The following values are suitable:
SCC2 will be set to handle a 9600 baud UART from a non-lSDN terminal. The following val-
ues are suitable:
SCC3 will be set to handle the HDLC frames of LAPD protocol over the D-channel. (Multi-
plexing SCC3 into lDL leaves the SCP pins available for the SCP port.) The following values
are suitable:
NOTE
In addition to programming the SCCs registers, the protocol-
specific parameter RAM of each SCC should be initialized by the
control software according to the protocol selected.
Register
Value
Comments
Configuration Register (SCONE)
$30FF
External receive and transmit clocks will be provid-
ed from the IDL through the serial Interface.
Mode Register (SCM1) for V.120
$000C
HDLC mode.
Mode Register (SCM1) for V. 110
$040E
V.110 mode.
Sync Register (DSR1)
$7E7E
HDLC flag.
Sync Register (DSR1)
$0100
V.110 sync pattern
Mask Register (SCCM1)
The mask should be set according to the interrupt
events handled.
Register
Value
Comments
Configuration Register (SCON2)
$30FF
Set internal receive and transmit clocks, 9600 baud
if 16.6-MHz parallel clock used.
Mode Register (SCM2)
$010D
UART mode, 8 bits, no parity
Sync Register (DSR2)
$7E7E
Bits 14-12 control stop-bit shaving.
Mask Register (SCCM2)
The mask should be set in accordance with the in-
terrupt events the software wants to handle.
Register
Value
Comments
Configuration Register (SCON3)
$3000
External receive and transmit clocks (will be pro-
vided from the IDL through the serial interface)
Mode Register (SCM3)
$010C
HDLC mode with retransmit option.
Sync Register (DSR3)
$7E7E
HDLC flag.
Mask Register (SCCM3)
$1B
The mask should be set in accordance with the in-
terrupt events the software wants to handle.