SAM4L_14 datasheet(74/176 Pages) ATMEL

74 / 176 page

42023GS–SAM–03/2014

ATSAM4L8/L4/L2

8.7.14

JTAG Instructions

Refer to the ARM Debug Interface v5.1 Architecture Specification for more details on ABORT,

DPACC, APACC and IDCODE instructions.

8.7.14.1

EXTEST

This instruction selects the boundary-scan chain as Data Register for testing circuitry external to

the chip package. The contents of the latched outputs of the boundary-scan chain is driven out

as soon as the JTAG IR-register is loaded with the EXTEST instruction.

Starting in Run-Test/Idle, the EXTEST instruction is accessed the following way:

Select the IR Scan path.

In Capture-IR: The IR output value is latched into the shift register.

In Shift-IR: The instruction register is shifted by the TCK input.

In Update-IR: The data from the boundary-scan chain is applied to the output pins.

Return to Run-Test/Idle.

Select the DR Scan path.

In Capture-DR: The data on the external pins is sampled into the boundary-scan chain.

In Shift-DR: The boundary-scan chain is shifted by the TCK input.

In Update-DR: The data from the scan chain is applied to the output pins.

10. Return to Run-Test/Idle.

8.7.14.2

SAMPLE_PRELOAD

This instruction takes a snap-shot of the input/output pins without affecting the system operation,

and pre-loading the scan chain without updating the DR-latch. The boundary-scan chain is

selected as Data Register.

Starting in Run-Test/Idle, the Device Identification register is accessed in the following way:

DR Size

Shows the number of bits in the data register chain when this instruction is active.

Example: 32 bits

DR input value

Shows which bit pattern to shift into the data register in the Shift-DR state when this

instruction is active.

DR output value

Shows the bit pattern shifted out of the data register in the Shift-DR state when this

instruction is active.

Table 8-4.

Instruction Description (Continued)

Instruction

Description

Table 8-5.

EXTEST Details

Instructions

Details

IR input value

0000 (0x0)

IR output value

p00s

DR Size

Depending on boundary-scan chain, see BSDL-file.

DR input value

Depending on boundary-scan chain, see BSDL-file.

DR output value

Depending on boundary-scan chain, see BSDL-file.

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