Is my brand new QT PY RP2040 defective?

[bluegizmo83]

I just received a QT PY RP2040 that I ordered, and this is my first Pi Pico board so maybe I'm doing something wrong, but I cannot get it to talk to my PC at all...

I've read online that you supposed to get it into the bootloader mode the first time to upload sketches to it (Arduino), but I cannot for the life of me get it into bootloader mode! According to the adafruit-qt-py-2040.pdf manual online, it says to:

hold down the BOOT/BOOTSEL button, and while continuing to hold it (don't let go!), press and release the reset button, Continue to hold the BOOT/BOOTSEL button until the RPI-RP2 drive appears!

The problem is, no drive ever appears! I've tried and tried and tried. I'm beginning to wonder if the BOOT button isn't working. I know the Reset button is working, because the neopixel LED goes off momentarily when I press the reset button. I also know the USB-A to USB-C cable I'm using is a known good cable for both power and data transfer, I even tested it with another microcontroller to be sure (an ESP32, not a 2040).

Any ideas?

[mikeysklar]

Have you tried the plugin and hold bootsel until the drive appears?

You can also start with your board unplugged from USB, press and hold the BOOTSEL button (highlighted in red above), continue to hold it while plugging it into USB, and wait for the drive to appear before releasing the button.

https://learn.adafruit.com/adafruit-qt- ... cuitpython

[bluegizmo83]

Have you tried the plugin and hold bootsel until the drive appears?

You can also start with your board unplugged from USB, press and hold the BOOTSEL button (highlighted in red above), continue to hold it while plugging it into USB, and wait for the drive to appear before releasing the button.

https://learn.adafruit.com/adafruit-qt- ... cuitpython

Yeah, tried that too. No drive ever shows up, PC doesn't make any sound (like usually when a USB device is connected you'll hear a sound), and device manager doesn't show anything either.

[mikeysklar]

Well it sounds like you have good cable so the problem is more likely with the OS or the USB port you are using. Which USB port is it on your PC? Do you have another machine a Raspberry Pi, Linux Box, Windows or Mac you can connect to? If any of those are also not showing the device then we should do a replacement.

[bluegizmo83]

Well it sounds like you have good cable so the problem is more likely with the OS or the USB port you are using. Which USB port is it on your PC? Do you have another machine a Raspberry Pi, Linux Box, Windows or Mac you can connect to? If any of those are also not showing the device then we should do a replacement.

On my Windows 10 PC that I was originally trying it with I had tried it using the onboard motherboard USB ports and then by using a USB hub as well.

I had not tried it on a different machine though so I just went ahead and tried that just now. I just tried it with a Raspberry Pi 4 running Raspbian OS and it's doing the same this. Nothing happens on the Pi when I plug it in, no drive shows up when I do the bootloader process, and typing lsusb in a terminal shows no new USB devices after it's plugged in or after trying the bootloader process.

I've never returned anything through Adafruit before. How do I go about starting a return for replacement?

[mikeysklar]

Thanks for trying on another machine.

Please send an e-mail to [email protected] requesting a replacement. Provide a link to this forum thread and your original order#.

[bluegizmo83]

Thanks for trying on another machine.

Please send an e-mail to [email protected] requesting a replacement. Provide a link to this forum thread and your original order#.

Ok, thanks for your help!

[bluegizmo83]

Just an FYI, I received my replacement Qt Py RP2040 today and the bootloader is working on this one! I had no problem accessing it and uploading an Arduino sketch.

However, the NeoPixel on this board does not appear to work at all. So thats now two Qt Py RP2040 boards in a row that I've received with defective parts...

On the first Qt Py RP2040 board that I received (the one with the non-functional bootloader), as soon as I plugged it into a USB-C cable the NeoPixel began cycling through a rainbow color effect, I assume due to a pre-loaded sketch it comes shipped with.

This replacement unit did not do that when plugged into power. I tried uploading the NeoPixel Blink Sketch from https://learn.adafruit.com/adafruit-qt-py-2040/blink-2 and it appears to have uploaded ok as I can see the repeated "Hello!" serial monitor messages after uploading, but the onboard NeoPixel doesn't turn on or do anything.

I'm not going to be seeking a replacement unit for this issue, as its not a huge deal that the onboard NeoPixel doesn't work, but I thought it was worthy of a note on the forums here that I've received two defective Qt Py RP2040 boards in a row now. One with a major issue that made the unit unusable, and one with a minor issue that I'm choosing to live with.

[mikeysklar]

Thank you for the follow up. I'm sorry the hear about the NeoPixel. If you want to take the time to take a photo of the board maybe there is something we can observe (eg. neopixel unsoldered pin?). You can also e-mails [email protected] for another replacement.

[bluegizmo83]

Hi again! Just posting another update.

I decided to take a look at that first defective QT PY RP2040 that I received to see if I could figure out why it wasn't working (I wasn't asked to send it back, so I still have it). If you'll recall, it had a non-functional bootloader/USB connection.

After looking it over closely and comparing it to the working QT PY RP2040 that I received as a replacement, I found a missing diode on the defective board. After tracing the PCB from that diode, it is supposed to make a connection to a trace that goes to the BOOT button on the other side of the board through a via hole, so I'm pretty sure this missing diode is the issue. It looks like this diode was just accidently left off the PCB during assembly as the solder pads still look new like nothing was ever soldered there. See the photos below. Sorry for the bad picture quality!

Known good working QT PY RP2040:

RP2040_With_Diode.jpg (770.92 KiB) Viewed 856 times

Non-functional bootload/USB connection QT PY RP2040:

RP2040_Missing_Diode.jpg (690.05 KiB) Viewed 856 times

Here is a screenshot of the 3D model showing that diode better:
In the model files, that diode is listed as SOD-323_MINI:D2 and the board files lists that diode as an NSR0320

RP2040_3D_Model.jpg (220.43 KiB) Viewed 856 times

[mikeysklar]

Thank you for the photos. They clearly show the missing diode and that is helpful. Do you happen to have the original bag for the Qt Py RP2040 that was missing a diode? I believe there can sometimes be batch information on it.

[bluegizmo83]

Thank you for the photos. They clearly show the missing diode and that is helpful. Do you happen to have the original bag for the Qt Py RP2040 that was missing a diode? I believe there can sometimes be batch information on it.

Yup here you go:

PXL_20220419_224002724.jpg (734.12 KiB) Viewed 846 times

The good functional replacement I received came from the same batch as well though (assuming the W13315-B is the batch number)

[mikeysklar]

Also good to know. Thank you for all your help.