AN 886: Intel Agilex® 7 Device Design Guidelines

ID 683634
Date 10/09/2023
Public
Document Table of Contents

6.2.2. Embedded Software Debugging and Trace

This device has just one JTAG port with FPGA and HPS JTAGs that can be chained together or used independently.

GUIDELINE: Intel® recommends to have an available JTAG connection to the board that could be used for development as well as to debug and diagnose field issues.

The HPS offers two trace interfaces either through HPS Dedicated I/O or FPGA I/O. The interface through HPS Dedicated I/O is a 16-bit DDR interface that you can use to trace low bandwidth traffic (such as the MPU operating at a low frequency).

To improve the trace bandwidth, you can use the standard trace interface which is a 32-bit single data rate interface to the FPGA. Since trace modules typically expect trace data to be sent at a double data rate you need to convert the single data rate trace data to double data rate.

Intel® recommends that you instantiate the DDIO Megawizard IP and set it up in output only mode to perform this conversion. The lowest 16 bits of trace data must be sent off chip first so you connect those bits to the datain_l[15:0] port of the DDIO IP.

Consult your trace vendor's datasheet to determine if the trace bus requires termination. Failure to include termination when the trace vendor requires it can lead to trace data corruption or limit the maximum operating frequency of the interface.
Figure 14. Trace Diagram

The HPS Debug Access Port (DAP) can be accessed through dedicated HPS pins configured as JTAG, or it can be accessed through FPGA JTAG interface pins.

The option to access the HPS JTAG interface through the FPGA JTAG pins is available in the Intel® Quartus® Prime Pro Edition project.

At power up, the FPGA appears as the first device in the JTAG chain. Once the FPGA is configured with an image for which the HPS JTAG interface is made available to the FPGA JTAG pins, the HPS appears as the first interface in the JTAG chain; and the FPGA appears as the second interface. This requires different connection settings for the FPGA tools, like the Intel® Quartus® Prime Pro Edition Programmer when it is used at power up and after FPGA configuration.

GUIDELINE: You must have an available JTAG connection to the board that can be used for development as well as to debug and diagnose field issues.

The HPS offers two trace interfaces either through HPS Dedicated I/O or FPGA I/O. The interface through HPS Dedicated I/O is a slow trace interface that you can use to trace low bandwidth traffic (such as the MPU operating at a low frequency).