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Counting Modes Definitions
Quad Timer (TMR), Rev. 4
Freescale Semiconductor
13-7
13.7.6 Signed Count Mode
If the Count mode field is set to 101, the counter counts the primary clock source while the
selected secondary source provides the selected count direction (up/down).
13.7.7 Triggered Count Mode
If the Count mode field is set to 110, the counter will begin counting the primary clock source
after a positive transition (Negative Edge if IPS = 1) of the secondary input occurs. The counting
will continue until a compare event occurs, or another positive input transition is detected. If a
second input transition occurs before a terminal count was reached, counting will stop.
Subsequent odd numbered edges of the secondary input will restart counting, while even
numbered edges will stop counting. This will continue until a compare event occurs.
13.7.8 One-Shot Mode
This is a sub mode of triggered event Count mode if the Count mode field is set to 110 while:
Count Length (LENGTH) is set
OFLAG Output mode is set to 101
ONCE bit of the Control (CTRL) register is set to 1
In the above setting, the counter works in a One-Shot mode. An external event causes the counter
to count. When terminal count is reached, the OFLAG output is asserted. This delayed output
assertion can be used to provide timing delays.
13.7.9 Cascade Count Mode
If the Count mode field is set to 111, the counter’s input is connected to the output of another
selected counter. The counter will count up and down as compare events occur in the selected
source counter. This Cascade or Daisy Chained mode enables multiple counters to be cascaded in
order to yield longer counter lengths. When operating in the Cascade mode, a special high speed
signal path is used not using the OFLAG Output signal. If the Selected Source Counter is
counting up, and it experiences a compare event, the counter will be incremented. If the Selected
Source Counter is counting down and it experiences a compare event, the counter will be
decremented. Up to four counters may be cascaded to create a 64-bit wide synchronous counter.
Whenever any counter is read within a Counter module, all of the counters’ values within the
module are captured in their respective Hold Registers. This action supports the reading of a
cascaded counter chain. First read any counter of a cascaded counter chain, then read the Hold
Registers of the other counters in the chain. The Cascaded Counter mode is synchronous.
Note:
It is possible to connect counters together by using the other (non-cascade) Counter
modes and selecting the outputs of other counters as a clock source. In this case, the