Datasheet

711
32142D–06/2013
ATUC64/128/256L3/4U
29. ADC Interface (ADCIFB)
Rev:1.0.1.1
29.1 Features
• Multi-channel Analog-to-Digital Converter with up to 12-bit resolution
• Enhanced Resolution Mode
– 11-bit resolution obtained by interpolating 4 samples
– 12-bit resolution obtained by interpolating 16 samples
• Glueless interface with resistive touch screen panel, allowing
– Resistive Touch Screen position measurement
– Pen detection and pen loss detection
• Integrated enhanced sequencer
– ADC Mode
– Resistive Touch Screen Mode
• Numerous trigger sources
– Software
– Embedded 16-bit timer for periodic trigger
– Pen detect trigger
– Continuous trigger
– External trigger, rising, falling, or any-edge trigger
– Peripheral event trigger
• ADC Sleep Mode for low power ADC applications
• Programmable ADC timings
– Programmable ADC clock
– Programmable startup time
29.2 Overview
The ADC Interface (ADCIFB) converts analog input voltages to digital values. The ADCIFB is
based on a Successive Approximation Register (SAR) 10-bit Analog-to-Digital Converter (ADC).
The conversions extend from 0V to ADVREFP.
The ADCIFB supports 8-bit and 10-bit resolution mode, in addition to enhanced resolution mode
with 11-bit and 12-bit resolution. Conversion results are reported in a common register for all
channels.
The 11-bit and 12-bit resolution modes are obtained by interpolating multiple samples to acquire
better accuracy. For 11-bit mode 4 samples are used, which gives an effective sample rate of
1/4 of the actual sample frequency. For 12-bit mode 16 samples are used, giving a effective
sample rate of 1/16 of actual. This arrangement allows conversion speed to be traded for better
accuracy.
Conversions can be started for all enabled channels, either by a software trigger, by detection of
a level change on the external trigger pin (TRIGGER), or by an integrated programmable timer.
When the Resistive Touch Screen Mode is enabled, an integrated sequencer automatically con-
figures the pad control signals and performs resistive touch screen conversions.
The ADCIFB also integrates an ADC Sleep Mode, a Pen-Detect Mode, and an Analog Compare
Mode, and connects with one Peripheral DMA Controller channel. These features reduce both
power consumption and processor intervention.