AT32UC3L064-D3HES ATMEL [ATMEL Corporation], AT32UC3L064-D3HES Datasheet - Page 661

• Manufacturer Part Number: AT32UC3L064-D3HES
• Manufacturer: ATMEL [ATMEL Corporation]

28.6.6
32099D–06/2010
Spread Spectrum Sensor Drive
Figure 28-4. CAT Acquisition and Processing Sequence
To reduce electromagnetic compatibility issues, the capacitive sensors can be driven with a
spread spectrum signal. To enable spread spectrum drive for a specific acquisition type, the
user must write a one to the SPREAD bit in the appropriate Configuration Register 1 (MGCFG1,
ATCFG1, TGACFG1, or TGBCFG1).
During spread spectrum operation, the length of each pulse within a burst is varied in a deter-
ministic pattern, so that the exact same burst pattern is used for a specific burst length. The
maximum spread is determined by the MAXDEV field in the Spread Spectrum Configuration
Register (SSCFG) register. The prescaler divisor is varied in a sawtooth pattern from
(2(DIV+1))-MAXDEV to (2(DIV+1))+MAXDEV and then back to (2(DIV+1))-MAXDEV. For exam-
ple, if DIV is 2 and MAXDEV is 3, the prescaler divisor will have the following sequence: 6, 7, 8,
No
touch detection
Autonomous touch
enabled (ATEN)?
autonomous
autonomous
touch count
Yes
algorithm
Acquire
Update
No
Idle
AISR written flag set?
Yes
AT32UC3L016/32/64
to be transferred
acquired counts
Acquire counts
Clear AISR
written flag
Wait for all
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