atmega323l ATMEL Corporation, atmega323l Datasheet - Page 157

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

JTAG Interface and
the On-chip Debug
System
Features
Overview
1457G–AVR–09/03
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The AVR IEEE std. 1149.1 compliant JTAG interface can be used for
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A brief description is given in the following sections. Detailed descriptions for Program-
ming via the JTAG interface, and using the Boundary-Scan Chain can be found in the
sections “Programming via the JTAG Interface” on page 202 and “IEEE 1149.1 (JTAG)
Boundary-Scan” on page 164, respectively. The On-chip Debug support is considered
being private JTAG instructions, and distributed within ATMEL and to selected third
party vendors only.
Figure 85 shows a block diagram of the JTAG interface and the On-chip Debug system.
The TAP Controller is a state machine controlled by the TCK and TMS signals. The TAP
Controller selects either the JTAG Instruction Register or one of several Data Registers
as the scan chain (Shift Register) between the TDI – input and TDO – output. The
Instruction Register holds JTAG instructions controlling the behavior of a Data Register.
Of the Data Registers, the ID-Register, Bypass Register, and the Boundary-Scan Chain
are used for board-level testing. The JTAG Programming Interface (actually consisting
of several physical and virtual Data Registers) is used for Serial Programming via the
JTAG interface. The Internal Scan Chain and Break Point Scan Chain are used for On-
chip debugging only.
JTAG (IEEE std. 1149.1 Compliant) Interface
Boundary-Scan Capabilities According to the JTAG Standard
Debugger Access to:
Extensive On-chip Debug Support for Break Conditions, Including
Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface
On-chip Debugging Supported by AVR Studio
– All Internal Peripheral Units
– Internal and External RAM
– The Internal Register File
– Program Counter
– EEPROM and Flash Memories
– Break on Change of Program Memory Flow
– Single Step Break
– Program Memory Break Points on Single Address or Address Range
– Data Memory Break Points on Single Address or Address Range
Testing PCBs by using the JTAG Boundary-Scan Capability.
Programming the Non-volatile Memories, Fuses and Lock bits.
On-chip Debugging.
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ATmega323(L)
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