attiny13-20ss ATMEL Corporation, attiny13-20ss Datasheet - Page 96

• Manufacturer Part Number: attiny13-20ss
• Description: 8-bit Microcontroller With 1k Bytes In-system Programmable Flash - Atmel Corporation
• Manufacturer: ATMEL Corporation

debugWIRE On-chip
Debug System
Features
Overview
Physical Interface
96
ATtiny13
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The debugWIRE On-chip debug system uses a One-wire, bi-directional interface to con-
trol the program flow, execute AVR instructions in the CPU and to program the different
non-volatile memories.
When the debugWIRE Enable (DWEN) Fuse is programmed and Lock bits are unpro-
grammed, 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 52. The debugWIRE Setup
Figure 52 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:
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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
Pull-Up resistor on the dW/(RESET) line must be in the range of 10k to 20 k'.
However, the pull-up resistor is optional.
Connecting the RESET pin directly to V
dW
GND
dW(RESET)
CC
will not work.
VCC
1.8 - 5.5V
2535G–AVR–01/07