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SWDIO No target connected

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?

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Jon Diller over 5 years ago +2

I had this same issue with my STM32F446RE Nucleo board. This is what I had to do to get my onboard ST-Link to talk to uVision again: -Download the STM32 ST-LINK Utility tool and try to connect to...
Kevin over 6 years ago in reply to Andy Neil +1

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 the pack example are already setup to work on...

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0 Andy Neil over 6 years ago

Start by testing basic connectivity & comms with ST's ST-Link Utility:

* If that doesn't work, then you have a fundamental issue - nothing to do with Keil;

* If that does work, then the issue is somewhere in your Keil stuff ...
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0 Andy Neil over 6 years ago

Start by testing basic connectivity & comms with ST's ST-Link Utility:

* If that doesn't work, then you have a fundamental issue - nothing to do with Keil;

* If that does work, then the issue is somewhere in your Keil stuff ...
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0 Andy Neil over 6 years ago in reply to Andy Neil

community.st.com/.../47602-keil-swdio-no-target-connected
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0 Kevin over 6 years ago in reply to Andy Neil
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

the pack example are already setup to work on a board. Verify with one of those examples. This rules out issues with your code.

In the Keil IDE, under Project-> Options for Target -> on the "Debug" tab, on the top right of the dialog, next the "USE: ST-Link Debugger, click the "Settings" button - the "Cortex-M Target Driver Setup" dialog appears.

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

"st-link usb communication error" then see "uVISION DEBUGGER: ST-LINK USB communication error" at www.keil.com/.../3662.htm

Internal command error, make sure to check the command window for additional information, then see: "uVISION DEBUGGER: ST-Link Does Not Connect to STM32F4 Discovery Board" at www.keil.com/.../3634.htm

Internal command error" and then "Error while attempting to read 64 bytes from memory 0x00000000"

Check the Boot jumpers on the board to make sure you are booting to the correct memory

Internal command error" A previous program running on the board is locking up.

Pull the BOOT0 or BOOT pin high, and restart the board, and perform a flash erase.

In the Keil IDE, under Project-> Options for Target -> on the "Debug" tab, on the top right of the dialog, next the "USE: ST-Link Debugger, click the "Settings" button - the "Cortex-M Target Driver Setup" dialog appears. Try using "connect under reset", close the dialogs and then perform a flash erase.

Try other connection/reset option "Connect under Reset"

Internal DLL Error, then see "Internal DLL Error Debugging with ST-Link" at www.keil.com/.../3666.htm

Finally, try the ST-LINK Utilities to erase and reconfigure the device
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