416
8331B–AVR–03/12
Atmel AVR XMEGA AU
1149.1 compliant, and supports boundary scan. Any external programmer or on-chip debug-
ger/emulator can be directly connected to either of these interfaces. Unless otherwise stated, all
references to the PDI assume access through the PDI physical layer.
Figure 32-1.
The PDI with JTAG and PDI physical layers and closely related modules (grey).
32.3
PDI Physical
The PDI physical layer handles the low-level serial communication. It uses a bidirectional, half-
duplex, synchronous serial receiver and transmitter (just as a USART in USRT mode). The
physical layer includes start-of-frame detection, frame error detection, parity generation, parity
error detection, and collision detection.
In addition to PDI_CLK and PDI_DATA, the PDI_DATA pin has an internal pull resistor, V
CC
and
GND must be connected between the External Programmer/debugger and the device.
shows a typical connection.
Figure 32-2.
PDI connection.
The remainder of this section is intended for use only by third parties developing programmers
or programming support for Atmel AVR XMEGA devices.
PDI
Controller
JTAG Physical
(physical layer)
PDI Physical
(physical layer)
OCD
NVM
Controller
Program and Debug Interface (PDI)
PDI_CLK
PDI_DATA
TDO
TCK
TMI
TDI
NVM
Memories
Internal Interfaces
PDIBUS
Connector
PDI_CLK
PDI_DATA
Vcc
Vcc