When working with XSCT or XSDK in Vitis for Cortex-M1, you may encounter connection issues with the debug server. This can prevent loading programs or debugging on your target board. There are several potential causes and solutions for these connection problems.
Confirm Hardware Setup
First, double check that your hardware is set up properly. Make sure the target board is powered on and connected via a USB cable to your host computer. Verify that any jumpers or switches on the board are configured correctly for JTAG/SWD debugging. If using a separate JTAG/SWD debugger probe, ensure it is firmly connected to both the target board and host. Check that the debugger’s power light is on.
Update Hardware Drivers
Outdated or incorrect drivers for the debug hardware can disrupt the server connection. Go to the device manufacturer’s website and download the latest drivers. For Xilinx boards, you can get drivers from the Vitis unified software platform. Install or update the drivers as needed. Reboot your system after installing new drivers.
Configure Server Connection Settings
The connection settings in XSCT/XSDK may need to be adjusted for your JTAG/SWD hardware. In the debug configuration, ensure the correct debugger device is selected. The default is often usb, indicating an onboard debugger chip. But you may need jtag or swd for an external probe. The interface clock rate can usually be left at the default, but may need to be reduced for connections over long cables or adapters. Lower values are generally more reliable.
Check Ports and Connectivity
Connection issues can arise if there are problems with ports or connectivity between the target and host. If using an onboard debugger, verify it is mapped to the correct USB port. Try disconnecting other USB devices to isolate the target board. For an external debugger probe, switch to a different USB port on the host computer. Check that you have any required drivers for the probe installed. Scan for errors in the USB connection reported by the OS.
Disable Firewall and Security Software
Firewalls, antivirus applications, VPN clients, and other security software can sometimes interfere with debugger communications. Temporarily disable these on your computer and test if the connection improves. Remember to re-enable any security software afterwards. You may need to add exceptions for XSCT/XSDK to allow communication through firewalls. Consult your IT department for assistance if needed.
Update to Latest Software Versions
Using older versions of Vitis, Xilinx runtime libraries, and other software components can result in compatibility issues. Update to the newest releases of Vitis, XRT, firmware, and other packages. Make sure the toolchain, runtime, and software platform match the versions used for your application. Keeping up to date with releases ensures maximum debugger compatibility.
Check Network Connectivity
For remote debugging over JTAG, the network connectivity between the host and target devices is critical. Connect both systems to the same local network and confirm they can reach each other with a ping test. Try connecting via Ethernet instead of WiFi for more reliability. Disable virtual private networks that may block access between local devices. Configure any firewalls to allow traffic on the ports used for communication.
Verify Target Power and Reset
Loss of power or the target resetting during debugging can cause disconnections. Check target power supplies are delivering proper regulated voltage levels. Use decoupling capacitors close to chips to filter noise. Prevent accidental reset pin short circuits. Consider wiring pushbuttons to manually reset target boards while debugging instead of any auto-reset circuitry.
Reconnect Debugger Hardware
Over time, debugger hardware connections can work loose from repeated plugging/unplugging or moving setups. Disconnect and reconnect both ends of any debugger probe cable. Check for bent pins or debris buildup on Arm Cortex debug connectors. Reflash onboard debugger ICs in case the firmware was corrupted. For intermittent problems, try replacing debugger probe and target cables.
Reduce Interface Speed
Higher clock speeds can sometimes exceed cable or PCB trace capabilities leading to signal integrity issues. In XSCT/XSDK debug configurations, reduce JTAG/SWD clock frequency progressively until communications are reliable. Typically lower speeds below 1 MHz work best for longer connections. Target power delivery quality also impacts maximum interface speed.
Update Target Firmware/BIOS
Old firmware or BIOS versions on evaluation boards may not support JTAG/SWD debugging fully. Check vendor websites for updates to flash on the target system. Newer firmware often resolves bugs and adds improved compatibility. Flashing the debug controller chip may also resolve problems if its firmware is outdated.
Try Alternative Debug Interfaces
If you continue experiencing intermittent JTAG or SWD issues, switching between the interfaces may improve reliability. The target board and debugger probe must support both options. JTAG is more noise resistant while SWD is faster but more prone to disconnects. Alternating between them during debugging can help work around problems.
Fix Board Design Bugs
For custom boards, PCB layout problems like inadequate decoupling, missing series termination, vias under BGA chips, or impedance mismatches can prevent robust Arm Cortex debug connections. Careful review of schematics and layout against processor datasheets is needed. Consider probing signals with an oscilloscope to check for issues.
Summary
XSCT and XSDK server connection issues can be frustrating but are usually resolvable. Double checking hardware setups, updating software and firmware, adjusting configurations, and trying alternate interfaces or slower speeds will often fix problems. For intermittent issues, replacing cables and adding board-level filtering may be necessary. With improved connections, you can focus on your embedded software development.
