Microchip Technology MPLAB ICD 5 User Manual

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User Guide
© 2023 Microchip Technology Inc. and its subsidiaries
DS-50003529B - 35
Important: If the JTAGEN fuse is unintentionally disabled, it can only be re-enabled using
the PDI physical interface.
If the JTAGEN fuse is programmed, the JTAG interface can still be disabled in rmware by setting the
JTAG disable bit in the MCU Control Register. This will render code un-debuggable and should not
be done when attempting a debug session. If such code is already executing on the Microchip AVR
device when starting a debug session, the MPLAB ICD 5 will assert the RESET line while connecting.
If this line is wired correctly, it will force the target AVR device into Reset, thereby allowing a JTAG
connection.
If the JTAG interface is enabled, the JTAG pins cannot be used for alternative pin functions. They will
remain dedicated JTAG pins until either the JTAG interface is disabled by setting the JTAG disable bit
from the program code, or by clearing the JTAGEN fuse through a programming interface.
Tip:
Selecting the “use external reset” checkbox, in both the programming dialog and debug
options dialog in Microchip Studio, allows the MPLAB ICD 5 to assert the RESET line. This
also re-enables the JTAG interface on devices, which are running code that disables the
JTAG interface by setting the JTAG disable bit.
Debugging with Sleep for ATxmegaA1 rev H and Earlier
A bug existed on early versions of ATxmegaA1 devices that prevented the OCD from being enabled
while the device was in certain sleep modes. There are two work-arounds to re-enable OCD:
• Go into the MPLAB ICD 5. Options in the Tools menu and enable “Always activate external Reset
when reprogramming device.”
• Perform a chip erase.
The sleep modes that trigger this bug are:
• Power-Down
• Power-Save
• Standby
• Extended Standby
4.3.1.5 debugWIRE OCD Features
The debugWIRE OCD is a specialized OCD module with a limited feature set specially designed for
AVR devices with low pin-count. It supports the following features:
• Complete program ow control
• Full access to all registers and memory areas
• Unlimited user program breakpoints (using BREAK instruction)
• Automatic baud rate conguration based on target clock
4.3.1.5.1 debugWIRE Special Consideraons
The debugWIRE communication pin (dW) is physically located on the same pin as the external Reset
(RESET). An external Reset source is, therefore, not supported when the debugWIRE interface is
enabled.
The debugWIRE Enable (DWEN) fuse must be set on the target device for the debugWIRE interface to
function. This fuse is by default unprogrammed when the Microchip AVR device is shipped from the
factory. The debugWIRE interface itself cannot be used to set this fuse. To set the DWEN fuse, the SPI

Microchip Technology MPLAB ICD 5 Specifications

General

Brand	Microchip Technology
Model	MPLAB ICD 5
Category	Microcontrollers
Language	English