Datasheet

572
32133D–11/2011
UC3D
27.5.2 Clocks
The clock for the CAT module, CLK_CAT, is generated by the Power Manager (PM). This clock
is turned on by default, and can be enabled and disabled in the PM. The user must ensure that
CLK_CAT is enabled before using the CAT module.
27.5.3 Interrupts
The CAT interrupt request line is connected to the interrupt controller. Using CAT interrupts
requires the interrupt controller to be programmed first.
27.5.4 Peripheral Direct Memory Access
The CAT module provides handshake capability for a Peripheral DMA Controller. One hand-
shake controls transfers from the Acquired Count Register (ACOUNT) to memory.Two additional
handshakes support DMATouch by regulating transfers from memory to the DMATouch State
Write Register (DMATSW) and from the DMATouch State Read Register (DMATSR) to memory.
The Peripheral DMA Controller must be configured properly and enabled in order to perform
direct memory access transfers to/from the CAT module.
27.5.5 Debug Operation
When an external debugger forces the CPU into debug mode, the CAT continues normal opera-
tion. If the CAT is configured in a way that requires it to be periodically serviced by the CPU
through interrupts or similar, improper operation or data loss may result during debugging.
27.6 Functional Description
27.6.1 Acquisition Types
The CAT module can perform several types of QTouch acquisition from capacitive touch sen-
sors: autonomous QTouch (one sensor only), DMATouch, QTouch group A, and QTouch group
B. Each type of acquisition has an associated set of pin selection and configuration registers that
allow a large degree of flexibility.
The following schematic diagrams show typical hardware connections for QTouch sensors:
Figure 27-2. CAT Touch Connections
In order to use the autonomous QTouch detection capability, the user must first set up the
Autonomous Touch Pin Select Register (ATPINS) and Autonomous/DMA Touch Configuration
Registers (ATCFG0 through 3) with appropriate values. The module can then be enabled using
AVR32 Chip
QTouch
Sensor
Cs (Sense Capacitor)
SNSKn
SNSn