Datasheet

Table Of Contents
55
XMEGA A4U [DATASHEET]
Atmel-8387H-AVR-ATxmega16A4U-34A4U-64A4U-128A4U-Datasheet_09/2014
31. Programming and Debugging
31.1 Features
z Programming
z External programming through PDI interface
z Minimal protocol overhead for fast operation
z Built-in error detection and handling for reliable operation
z Boot loader support for programming through any communication interface
z Debugging
z Nonintrusive, real-time, on-chip debug system
z No software or hardware resources required from device except pin connection
z Program flow control
z Go, Stop, Reset, Step Into, Step Over, Step Out, Run-to-Cursor
z Unlimited number of user program breakpoints
z Unlimited number of user data breakpoints, break on:
z Data location read, write, or both read and write
z Data location content equal or not equal to a value
z Data location content is greater or smaller than a value
z Data location content is within or outside a range
z No limitation on device clock frequency
z Program and Debug Interface (PDI)
z Two-pin interface for external programming and debugging
z Uses the Reset pin and a dedicated pin
z No I/O pins required during programming or debugging
31.2 Overview
The Program and Debug Interface (PDI) is an Atmel proprietary interface for external programming and on-chip
debugging of a device.
The PDI supports fast programming of nonvolatile memory (NVM) spaces; flash, EEPOM, fuses, lock bits, and the
user signature row.
Debug is supported through an on-chip debug system that offers nonintrusive, real-time debug. It does not require any
software or hardware resources except for the device pin connection. Using the Atmel tool chain, it offers complete
program flow control and support for an unlimited number of program and complex data breakpoints. Application
debug can be done from a C or other high-level language source code level, as well as from an assembler and
disassembler level.
Programming and debugging can be done through the PDI physical layer. This is a two-pin interface that uses the
Reset pin for the clock input (PDI_CLK) and one other dedicated pin for data input and output (PDI_DATA). Any
external programmer or on-chip debugger/emulator can be directly connected to this interface.
32. Pinout and Pin Functions
The device pinout is shown in “Pinout/Block Diagram” on page 4. In addition to general purpose I/O functionality, each
pin can have several alternate functions. This will depend on which peripheral is enabled and connected to the actual
pin. Only one of the pin functions can be used at time.
32.1 Alternate Pin Function Description
The tables below show the notation for all pin functions available and describe its function.