Datasheet

212
ATtiny828 [DATASHEET]
8371A–AVR–08/12
20. debugWIRE On-chip Debug System
20.1 Features
z Complete Program Flow Control
z Emulates All On-chip Functions, Both Digital and Analog , except RESET Pin
z Real-time Operation
z Symbolic Debugging Support (Both at C and Assembler Source Level, or for Other HLLs)
z Unlimited Number of Program Break Points (Using Software Break Points)
z Non-intrusive Operation
z Electrical Characteristics Identical to Real Device
z Automatic Configuration System
z High-Speed Operation
z Programming of Non-volatile Memories
20.2 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.
20.3 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.
Figure 89 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.
Figure 89. The debugWIRE Setup
dW
GND
dW(RESET)
VCC
1.8 - 5.5V