I'm using a stm32f407vg board. Suddenly I can't download my code to flash memory. It gives me this error " Debugger - Cortex-M error: no target connected". In options for target > Debug > Settings in SW Device tab I see " SWDIO: Error No target connected".
How can I solve this?
I assume you are connecting using the on board debugger. If so, here are some ideas for troubleshooting a ST-Link.
I) Test with a pack example
If the top right of the dialog says "No ST-Link detected", or on the top left, next to "Unit" the pull down box is empty: - Make sure there are no Windows USB drivers or board debugger firmware issues. If not - Swap out USB cables - Don't connect the ST-Link to your computer via USB hub
If the box on the top left says - "Unknown target connected" - On the middle-left of the screen, in the 'Target Com" box, switch the Port from "JTAG" to "SW" - ST-LINK requires a Serial Wire interface, not JTAG.
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If that works, close the dialogues. Still using the sample pack example, Select Debug-> Start/ Stop debug session. If you get a pop up box, that says