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II
Minimum values for the PTP register are:
Physical
Bit Rate
Layer Type
(Mb/Sec)
m
m
m
m
m
b
b
b
p
p
p
p
p
p
p
p
Single Channel Phase
Continuous FSK
1
0
0
0
0
0
0
0
0
1
0
1
0
1
0
1
0
Single Channel Phase
5
0
0
0
0
1
1
1
1
1
0
1
0
1
0
1
0
Coherent FSK
10
0
0
0
1
0
1
1
1
1
0
1
0
1
0
1
0
Broadband Bus
1
0
0
0
0
0
0
1
0
1
0
1
0
1
0
1
0
5
0
0
0
0
1
0
1
0
1
0
1
0
1
0
1
0
10
0
0
0
1
0
0
1
0
1
0
1
0
1
0
1
0
The values for 'mmmmm' and 'bbb' in the above table are minimum values. The user may use
larger values for 'mmmmm' to enhance back-to-back frame reception, or may use larger values
for 'bbb' if a non-standard modem being used requires more preamble after silence.
The PTP register bits have different meanings when being used in the receive test. See 3.6.5
RECEIVER TEST Command for more details.
3.5.3.5 SET ONE WORD. The SET ONE WORD command is used to set two-byte TBC operational
parameters residing in the private area. The host must load the opcode into CPA VALO and the
new parameter value in CPA VAL 1 before writing the SET ONE WORD command into the command
register. The opcodes for the SET ONE WORDITWO WORDS commands are listed in Table 3-7.
The
co~ing
for this command is 86 and its format is shown below:
1
I
0
I
0
o
I
0
I
1
I
1
I
0
3.5.3.6 SET TWO WORDS. The SET TWO WORDS command is used to set four-byte TBC param-
eters which reside in the private area. The host must load the opcode into CPA VALO and the new
parameter value high order word in CPA VAL 1 and low order word in CPA VAL2 before writing
the SET TWO WORDS command into the command register. The coding for this command is 85
and its format is shown below:
1
I
0
I
0
o
I
0
I
1
I
0
I
1
The opcodes for the SET ONE WORDITWO WORDS commands are listed in Table 3-7.
3.6 TESTING
Commands in this category were designed to facilitate debugging and diagnostics tasks on a TBC
system. There are four available tests which can be run on the TBC while in the OFFLINE state.
The receiver test, transmitter test, and full duplex loopback test may be run in either internal or
external loopback mode, see 3.6.1 SET INTERNAUEXTERNAL LOOPBACK MODE Command for
a description. The codings for the test commands are BO through BC and the format is:
MOTOROLA
3-18
1
I
0
I
1
I
1
T
T
T
T
MC68824 USER'S MANUAL
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