Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

The implemented JTAG instructions in the 32-bit AVR are shown in the table below.

When the security fuse in the Flash is programmed, the following JTAG instructions are
restricted:

• NEXUS_ACCESS

• MEMORY_WORD_ACCESS

• MEMORY_BLOCK_ACCESS

• MEMORY_SIZED_ACCESS

For description of what memory locations remain accessible, please refer to the SAB address
map.

Full access to these instructions is re-enabled when the security fuse is erased by the
CHIP_ERASE JTAG instruction.

Note that the security bit will read as programmed and block these instructions also if the Flash
Controller is statically reset.

JTAG Instruction Summary

0x01

IDCODE

Select the 32-bit Device Identification register as data register.

0x02

SAMPLE_PRELOAD

Take a snapshot of external pin values without affecting system operation.

0x03

EXTEST

Select boundary-scan chain as data register for testing circuitry external to 
the device.

0x04

INTEST

Select boundary-scan chain for internal testing of the device.

0x06

CLAMP

Bypass device through Bypass register, while driving outputs from boundary-
scan register. 

0x0C

AVR_RESET

Apply or remove a static reset to the device

0x0F

CHIP_ERASE

Erase the device

0x10

NEXUS_ACCESS

Select the SAB Address and Data registers as data register for the TAP. The 
registers are accessed in Nexus mode.

0x11

MEMORY_WORD_ACCESS

Select the SAB Address and Data registers as data register for the TAP.

0x12

MEMORY_BLOCK_ACCESS

Select the SAB Data register as data register for the TAP. The address is 
auto-incremented.

0x13

CANCEL_ACCESS

Cancel an ongoing Nexus or Memory access.

0x14

MEMORY_SERVICE

Select the SAB Address and Data registers as data register for the TAP. The 
registers are accessed in Memory Service mode.

0x15

MEMORY_SIZED_ACCESS

Select the SAB Address and Data registers as data register for the TAP.

0x17

SYNC

Synchronization counter

0x1C

HALT

Halt the CPU for safe programming.

0x1F

BYPASS

Bypass this device through the bypass register.

Others

N/A

Acts as BYPASS