Figure 35-8. Unbuffered Single-Slope Up-Counting Operation
COUNT
MAX
New TOP written to
PER that is higher
than current COUNT
Counter Wraparound
New TOP written to
PER that is lower
than current COUNT
"clear" update
"write"
ZERO
A counter wraparound can occur in any operation mode when up-counting without buffering, see
COUNT and TOP are continuously compared, so when a new TOP value that is lower than current
COUNT is written to TOP, COUNT will wrap before a compare match.
Figure 35-9. Unbuffered Single-Slope Down-Counting Operation
COUNT
MAX
New TOP written to
PER that is higher
than current COUNT
New TOP written to
PER that is lower
than current COUNT
"reload" update
"write"
ZERO
When double buffering is used, the buffer can be written at any time and the counter will still maintain
correct operation. The period register is always updated on the update condition, as shown in
. This prevents wraparound and the generation of odd waveforms.
Atmel SAM L22G / L22J / L22N [DATASHEET]
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