Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI Data Sheet
Product codes
MEGA328P-XMINI
254
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
25.
debugWIRE On-chip Debug System
25.1
Features
•
Complete Program Flow Control
•
Emulates All On-chip Functions, Both Digital and Analog, except RESET Pin
•
Real-time Operation
•
Symbolic Debugging Support (Both at C and Assembler Source Level, or for Other HLLs)
•
Unlimited Number of Program Break Points (Using Software Break Points)
•
Non-intrusive Operation
•
Electrical Characteristics Identical to Real Device
•
Automatic Configuration System
•
High-Speed Operation
•
Programming of Non-volatile Memories
25.2
Overview
The debugWIRE On-chip debug system uses a One-wire, bi-directional interface to control the program flow,
execute AVR instructions in the CPU and to program the different non-volatile memories.
execute AVR instructions in the CPU and to program the different non-volatile memories.
25.3
Physical Interface
When the debugWIRE Enable (DWEN) Fuse is programmed and Lock bits are unprogrammed, the debugWIRE
system within the target device is activated. The RESET port pin is configured as a wire-AND (open-drain) bi-
directional I/O pin with pull-up enabled and becomes the communication gateway between target and emulator.
system within the target device is activated. The RESET port pin is configured as a wire-AND (open-drain) bi-
directional I/O pin with pull-up enabled and becomes the communication gateway between target and emulator.
Figure 25-1.
The debugWIRE Setup
shows the schematic of a target MCU, with debugWIRE enabled, and the emulator connector. The
system clock is not affected by debugWIRE and will always be the clock source selected by the CKSEL Fuses.
When designing a system where debugWIRE will be used, the following observations must be made for correct
operation:
operation:
dW
GND
dW(RESET)
VCC
1.8 - 5.5V