3.1 Embedded Debugger

The ATtiny817 Xplained Pro contains an Embedded Debugger (EDBG) for on-board debugging. The EDBG is a USB composite device with the following interfaces:

  • Debugger
  • Virtual COM Port
  • Data Gateway Interface (DGI)

The EDBG can program and debug the ATtiny817 with the help of Atmel Studio/MPLAB® X. The UPDI interface is connected between the EDBG and the ATtiny817 on the ATtiny817 Xplained Pro.

The Virtual COM Port is connected to a UART on the ATtiny817 and provides an easy way to communicate with the target application through terminal software. It offers variable baud rate, parity, and stop bit settings. The settings on the ATtiny817 must match the settings given in the terminal software.

Info: The Virtual COM Port in the EDBG requires the terminal software to set the Data Terminal Ready (DTR) signal to enable the UART pins connected to the ATtiny817. If the DTR signal is not enabled, the UART pins on the EDBG are kept in tri-state (high-Z) to render the COM Port not usable. The DTR signal is automatically set by terminal software, but it may have to be manually enabled in your terminal.

The DGI consists of several physical interfaces for bidirectional communication with the host computer. Communication over the interfaces is bidirectional. It can be used to send event values and data from the ATtiny817. Traffic over the interfaces can be timestamped by the EDBG for more accurate tracking of events, but timestamping reduces the maximal data throughput. The Data Visualizer is used to send and receive data through DGI.

The EDBG controls two LEDs on the ATtiny817 Xplained Pro; a power LED and a status LED. The following table provides details on how the LEDs are controlled in different operation modes.

Table 3-1. EDBG LED Control
ModePower LEDStatus LED
Normal modeThe power LED is ON when power is applied to the board.Activity indicator, the LED flashes when any communication happens to the EDBG.
Bootloader mode (idle)The power LED and the status LED blink simultaneously.
Bootloader mode (firmware upgrade)The power LED and the status LED blink in an alternating pattern.

For additional information on the EDBG, see the EDBG User Guide.