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Register Description
63
Table 13: User Control Registers (Addresses 0xB000C020, 0xB000C024, 0xB000C028)
Bit
Register Description
Value
Type
1:0
User Clock Select [1:0]
These bits specify the clock for the user
counter/timer. These bits resets to 00 on
power up or Counter/Timer reset.
Bit 1 Bit 0
0
0 = Internal 18 MHz Clock
0
1 = External Clock
1
0 = Cascaded Clock
1
1 = Reserved
W
3:2
User Gate Select [1:0]
These bits specify the gate for the user
counter. These bits reset to 00 on power
up or Counter/Timer reset.
Bit 3 Bit 2
0
0 = Logic Low (disabled)
0
1 = Logic High (enabled)
1
0 = External Gate (high active)
1
1 = External Gate Inverted (low active)
W
5:4
User Mode Select [1:0]
These bits specify the mode for the user
counter. These bits reset to 00 on power
up or Counter/Timer reset.
Bit 5 Bit4
0
0 = Non-retriggerable One-Shot
0
1 = Retriggerable One-Shot
1
0 = Continuous Increment
1
1 = Auxiliary (see aux mode select bits)
W
6
User Output Polarity
This bit specifies the polarity for the user
output. This bit resets to 0 on power up or
Counter/Timer Reset.
0 = Low Active
1 = High Active
W
7
User One-Shot Trigger Enable Command
The host should set up all the
features/characteristics of the counter
before issuing this command.
0 = One-shot triggers disabled.
1 = One-shot triggers enabled.
W
9:8
User Aux Mode Select [1:0]
These bits specify the auxiliary mode for
the user counter/timer.They only matter if
the mode select bits specify auxiliary
mode. These bits reset to 00 on power up
or Counter/Timer reset.
Bit 9 Bit8
0
0 = Measure
0
1 = Up/down
1
0 = Reserved
1
1 = Reserved
W
11:10
User Measure Start Select [1:0]
These bits specify the edge that starts the
measurement. These bits reset to 00 on
power up or Counter/Timer reset.
Bit 11 Bit10
0
0 = Selected gate (external, external
inverted, or software) rises
0
1 = Selected gate (external, external
inverted or software) falls
1
0 = External clock rises
1
1 = External clock falls
W
13:12
User Measure Stop Select [1:0]
These bits specify the edge that stops the
measurement. These bits reset to 00 on
power up or Counter/Timer Reset.
Bit 13 Bit12
0
0 = Selected gate (external, external
inverted, or software) rises
0
1 = Selected gate (external, external
inverted, or software) falls
1
0 = External clock rises
1
1 = External clock falls
W
14
User Measure Enable Command
The host should set up all the
features/characteristics of the counter
before issuing this command.
1 = Enables the selected measurement.
0 = Clears the measure enable flag.
W
15
Reserved
a
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Summary of Contents for DT9840 Series
Page 1: ...DT9840 Series UM 19197 T User s Manual Title Page ...
Page 4: ......
Page 44: ...Chapter 1 44 ...
Page 76: ...Chapter 2 76 ...
Page 98: ...Appendix A 98 ...
Page 124: ...Appendix B 124 ...