ADUCM350BBCZ datasheet(34/41 Pages) AD

34 / 41 page

Data Sheet

ADuCM350

Rev. A | Page 33 of 40

AFE CONTROL

Figure 42. AFE Control

The AFE can be controlled by the ARM Cortex-M3 via MMRs.

All blocks within the AFE are fully controllable and observable

using the MMR registers. Access the MMRs through an AHB

bus or indirectly through a programmable sequencer. There are

two dedicated DMA channels to remove burden from the ARM

Cortex-M3 to manage data and control FIFOs.

The sequencer handles low level AFE operations and allows the

AFE to perform its functions independently. It performs cycle

accurate precision AFE measurements asynchronously of the

core.

The sequencer allows the user to create parameterized wave-

forms using the waveform generator block. The waveforms can

be trapezoids or sinusoids. Arbitrary waveforms are possible

using the AFE sequencer and DMA transfers.

Figure 43. Waveform Generation

CAPTOUCH FEATURES

The ADuCM350 incorporates a capacitive touch subsystem that

interfaces with up to six capacitive touch channels in self

capacitance mode and incorporates high performance

capacitance sensing circuitry without external components.

The sensor input configuration is very flexible and uses several

techniques to ensure that there are no false touches (that is, no

registering touches caused by a changing environment) on the

external sensors. To minimize noise pickup from the system,

the ADuCM350 CapTouch core includes several algorithms,

such as median and averaging filtering measurements, as well

as configurable excitation frequency and duty cycle. The

subsystem includes a self timer and touch-and-release routines

to optimize the power consumption and reduce the computing

workload in the ARM Cortex-M3.

Figure 44. CapTouch External Interface

ANALOG

BLOCKS

50Hz/60Hz

FILTER

SEQUENCER

COMMAND

FIFO

DSP

ACCELERATORS

DFT

WAVEFORM

GENERATOR

DATA

FIFO

(TO M3)

INTERRUPT

GENERATION

MMR

AFE

ARM

CORTEX-M3

SINE

GENERATION

TRAPEZOID

GENERATION

DAC CODE

(DC)

DAC

CapTouch

PCB

BU_ONOFF

CAPACITIVE

TOUCH

BU_LEFT

BU_RIGHT

BU_UP

BU_DOWN

BU_ENTER

AGND_TX

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