SAM4L Datasheet, PDF (911/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
34. Capacitive Touch Module (CATB)
Rev: 1.0.0.0
34.1 Features
• Low-power capacitive proximity and touch detection
• Touch filtering without CPU intervention
• Capacitance measurement on multiple sensors for button/slider/wheel support
• Autonomous interrupt generation on touch and out-of-touch events
• Autocalibration provides automatic adaptation to changing operating conditions
• Peripheral-event-triggered acquisition for autonomous sleep operation and synchronization
• Spread-spectrum operation for EMI compatibility
• Differential or single-ended sensing operation for measurement of both mutual and self
capacitance
• Support for internal and external discharge resistors
34.2 Overview
The Capacitive Touch Module (CATB) performs acquisition, filtering, and detection of capacitive
touch sensors. The capacitive touch sensors use no mechanical components, and therefore
demand less maintenance in the user application. The CATB can operate in different capaci-
tance discharge modes:
• Single-ended, with one pin per sensor
• Differential, with two pins per sensor
• External discharge resistors, with an extra pin (DIS) in single-ended mode
• Internal discharge resistors
Using DMA, the CATB can sense on multiple sensor pins. Refer to the Module Configuration
section for the number n of supported sensors. The CATB can report measured capacitance val-
ues to software algorithms for the implementation of buttons/sliders/wheels, and the user can
configure thresholds triggering interrupts.
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