7 Data Gateway Interface (DGI)

Data Gateway Interface (DGI) is a USB interface that transports raw and timestamped data between the Nano Debugger and host computer-based visualization tools. MPLAB Data Visualizer is used on the host computer to display any debug GPIO data. It is available as a plug-in for MPLAB X IDE or as a stand-alone application that can be used in parallel with MPLAB® X IDE.

Tip: The number of GPIO channels can vary depending on the device mounted on the kit. AVR devices have two channels, while all other device types have a single channel.

7.1 Debug GPIO

Debug GPIO channels are timestamped digital signal lines that connect the target application to a host computer visualization application. They are typically used to plot low-frequency events on a time axis, such as when specific application state transitions occur.

The figure below shows the monitoring of the digital state of a mechanical switch connected to a debug GPIO in MPLAB Data Visualizer.
Figure 7-1. Monitoring Debug GPIO with MPLAB Data Visualizer

Debug GPIO channels are timestamped, so the resolution of DGI GPIO events is determined by the DGI Timestamp module resolution.

Important: Although capturing higher-frequency signal bursts is possible, the frequency range in which the debug GPIO can be used is up to about 2 kHz. Attempting to capture signals above this frequency will result in data saturation and overflow, which may cause the DGI session to abort.

7.2 Timestamping

When captured by the debugger, DGI sources are timestamped. The timestamp counter implemented in the Curiosity Nano debugger increments at a frequency of 2 MHz, providing a timestamp resolution of half a microsecond.