QTAN0016 Datasheet, PDF (1/4 Pages) ATMEL Corporation – Diagnostic Modes for QT ICs

Diagnostic Modes for Products with Atmel^®
Capacitive-touch ICs
1. Introduction
There are many types of Atmel capacitive-touch integrated circuits (QT^™ ICs) with
interfaces as diverse as simple pin-per-key (PPK) to serial links for data
communication. To support product development throughout production testing, it is
often useful to obtain data from the QT IC by using the diagnostic modes in a
product’s main microcontroller (MCU).
This application note discusses the various points to be considered when designing
diagnostic modes for your product.
The topics in this application note include:
• Diagnostic mode entry
• Diagnostic data output
• Displayed information
• Pass-through from QT IC to PC
• Production testing
Diagnostic
Modes for QT
ICs
Application Note
QTAN0016
2. Why Do I Need Diagnostics?
Making diagnostic information readily available encourages monitoring and promotes
understanding of the product under development. It also permits the detection of
unusual conditions or, in the event of a fault, the retrieval of useful information while
the fault condition prevails.
3. Diagnostic Mode Entry
There are three basic methods of initiating diagnostic mode during product testing:
• Key sequence
• External command
• Option setting
3.1 Entry by Key Sequence
Key sequences are particularly useful because external equipment or product
modifications are not required. However, the method is not always successful if the
touch is not calibrated or if an error condition occurs.
A typical key sequence could be:
1. Press key A for 3 seconds, then release.
2. Press key B for 3 seconds, then release.
3. Press key C for 3 seconds, then release.
10704A–AT42–10/08