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Troubleshooting device connection

Sometimes, you may have problem with a device. You may have hard time to find it, hard time to flash it and after flash you may not find it in the Visual Studio extension. So this article is for you and will give you elements to figure out the root cause.

This example will use an ESP32 device but it works in a similar way for other devices.


We assume you have properly installed the .NET nanoFramework flash tool called nanoff. If not, go here.

We also assume you have properly installed the Visual Studio Extension. If not the case, then go here.

And finally, we assume you have a tool to watch port serial traffic like putty. If you don't have any, go here.

Finding the serial port of your device

The main trick here is to run 2 times the following command: nanoff --listports

Finding ports on Windows

The first time it will look like this on Windows:

list ports empty

Then once you plug your device and rerun the command, you will see your port:

list ports found

In this case, the com port is COM3 on Windows. Bravo!

In case you don't see anything at all, then make sure you have the proper drive installed. If you don't have the proper driver installed, you'll get in the device explorer an error. If all is properly installed, you'll also be able to find the port:

Finding COM Port

Finding ports on Linux/MacOS

And like this on MacOS/Linux with no device plugged in:

list ports empty

Once you plug the device, you'l get the port details:

list ports found

We'll use the tty one, so /dev/tty.usbserial-531F00209021. The naming can be very different depending on the device you are using. In all the cases, make sure the latest drivers are installed.

In case you won't find your device, it's recommended to install lsusb. For linux, depending on the version, just use apt-get install lsusb and for MacOS brew install lsusb (you may have to use higher privileges using sudo).

Then similar to using the nanoff command, unplug your device and run lsusb to list the connected devices. Run it a second time with the device connected to figure out what it is and which drivers are required. The result will looks like this:

lsusb empty

And with the added device:

lsusb empty

You can refer to the hardware found and then to the vendor to find out what drivers are needed.

My device flashes but I can't find it in Visual Studio extension

You've flashed the device successfully using nanoff but you don't see it in the Visual Studio Extension.

First, check this troubleshooting guide!

Still nothing? OK, let's debug the device itself.

Special ESP32

ESP32 devices at boot time will output quite a lot of things. For this, you need to connect your deviceESP32 with the proper serial port (in the previous example COM3 for Windows and /dev/tty.usbserial-531F00209021 for Linux/Mac) with a baud rate of 115200.

putty config

And when you connect and reset the device by pressing the little EN or BOOT or equivalent button of your ESP32, you'll get a result like this:

putty ESP32 outcome

If your device is ok, you should see all green, no red lines. If you have red lines, it may be related to an issue, that can point you on something broken in your device. If the device reboots all the time, you'll get this screen over and over, it then means the device can be out of order or you have a problem with the image.

If at this point all is good for your device, go to the next step.

Finding if nanoFramework booted

To know if your device boots properly, use putty or equivalent and open the serial port your device is connected to with the baud rate of 921600, this is the baud rate used by Console.WriteLine or Debug.WriteLine and whenever you have exceptions or equivalent raised by the CLR.

putty config

Regardless of your device, once you connect it, you will see the message NFPKTV1 appearing. This means that .NET nanoFramework is properly loaded and working. To see it, you may have to reboot your device by pressing buttons like EN, RST, BOOT or equivalent.

putty config

Don't worry about the possible scramble characters before, they are the ones from the boot of the device itself. Some devices like ESP32 are quite chatty (see previous section), some devices like STM32 are very quite!

From that point, seeing this message means the device is properly working, so look again at this troubleshooting guide.