The counter holds a single value, whose value is emitted on the output
Q. Each time the clock input (diagrammed with a triangle on the
component's south edge) triggers according to its Trigger attribute,
the value in the counter may update based on
the two inputs on the component's west edge: The upper input is called
load and the lower is called count, and they are
interpreted as follows.
|0 or z||0
||The counter remains unchanged.|
|0 or z||1 or z
||The counter increments.|
||The counter loads the value found at the
|1||1 or z
||The counter decrements.|
The range of counting can be configured using the Maximum
Value attribute. When the counter reaches this value, the next
increment wraps the counter back to 0; and if it is at 0,
then a decrement will wrap the counter around back to its maximum value.
In addition to the output Q, the component also includes a
single-bit output carry. This is 1 whenever the counter is at its
maximum and the load and count inputs indicate that the
component should increment on the next step - or when the counter is at 0
and the load and count inputs indicate to decrement at
the next step.
The clear input resets the counter's value to 0 (all
zeroes) asynchronously; that is, as long as the clr input
is 1, the value is pinned to 0, regardless of the clock input.
- East edge, labeled Q (output, bit width matches Data Bits attribute)
- Outputs the value currently stored by the counter.
- Ostseite, unterer Pin (Ausgang, Bitbreite 1)
- Carry: When load and count indicate to increment,
this output is 1 whenever the counter is at its maximum. When load
and count indicate to decrement, this output is 1 whenever the
counter is at 0. At all other times, this output is 0.
- West edge, top pin (input, bit width 1)
- Load: When this is 1 while the count input is 0, the counter
will load the value found at the data input at the next clock
trigger - or, if the count input happens to be 1, the counter's
value will decrement.
- West edge, middle pin labeled D
(input, bit with matches Data Bits attribute)
- Data: When the clock triggers while load is 1
and count is 0, the counter's value changes to the value found at
- West edge, lower pin labeled ct (input, bit width 1)
- Count: When this is 1 or unconnected, the value in the counter increments
whenever the clock input is triggered - or it decrements if the load
input happens to also be 1.
- South edge, indicated with a triangle (input, bit width 1)
- Clock: At the instant that this is triggered as specified by the Trigger
attribute, the counter updates as indicated by the load and
- South edge, labeled 0 (input, bit width 1)
- Clear: When 0 or undefined, this input has no effect.
As long as it is 1, the counter's value is asynchronously pinned to 0. This
occurs asynchronously - that is, without regard to the current clock input
value. As long as this is 1, the other inputs have no effect.
When the component is selected or being added,
Alt-0 through Alt-9 alter its
Data Bits attribute.
- Data Bits
- The bit width of the value emitted by the component.
- Maximum Value
- The maximum value, at which point the counter will set its carry output.
- Action On Overflow
- The behavior when the counter attempts to increment beyond the maximum value
or decrement beyond 0. Four possible actions are supported:
- Wrap around
- The next value is 0 (if incrementing - the maximum value if decrementing)
- Stay at value
- The counter's value remains at the maximum (or 0 if decrementing)
- Continue counting
- The counter continues incrementing/decrementing, keeping the number of bits
as provided by the Data Bits attribute
- Load next value
- The next value is loaded from the D input.
- Configures how the clock input is interpreted. The value
indicates that the counter should update its value at the instant when the
clock rises from 0 to 1. The
falling edge value indicates that it should
update at the instant the clock falls from 1 to 0.
- The text within the label associated with the component.
- Label Font
- The font with which to render the label.
Verhalten des Schaltwerkzeugs
Clicking the counter brings keyboard focus to the component
(indicated by a red rectangle), and typing hexadecimal digits will
change the value stored in the counter.
Verhalten des Textwerkzeugs
Allows the label associated with the component to be edited.
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