I was doing my development on the non QWIIC 3.3v version and in my haste to load the code to the new board, I forgot to change the jumper on the board to 3.3v. I sent 3.3v code to a 5v board and bricked it. It’s not the first time that I’ve done this, so I knew how to reset it. I’ve tried a lot of things including cutting the 5v trace and jumping the 3.3v, but basically it won’t finish uploading while its in boot before it resets past 8 second boot loader. Is there an alternate method that buys me even more time or any other tips?
To update, I can get an empty sketch to upload in bootloader mode now and it exits fine. As soon as the device shows up on the next COM port, windows can’t recognize it. Do I just have a faulty board?
I ordered another brand new board. Before I even plugged it in I cut the 5v trace and soldered the 3.3v jumper. Plugged it in and windows recognizes it. Uploaded my 3.3v code just fine and it reboots unrecognizable. Please help.
Could you explain the
Uploaded my 3.3v code just fine and it reboots unrecognizable.
part?
what code did you upload, and how did you upload it (using the IDE and a USB connection, or ISP)? It might be worth uploading the “blink” sketch to see if it actually programmed the sketch.
I have the Arduino IDE set with the Board as “SparkFun Pro Micro” and the Processor as ATmega32U4 (3.3v, 8 MHz) before uploading any sketch via USB connection. I tried blink on the previous board, but I can try it on this one as well.
It looks like I’ve been experiencing this, but the board is hooked up to nothing so I’m not sure why I’d be getting this symptom. https://learn.sparkfun.com/tutorials/qw … s-brownout
I’ve managed to get the blink program in the hookup guide to work on both my 5v jumpered board and my 3.3v jumpered board; but only if I set the processor in the IDE to 5v, 16MHz for BOTH the 5v jumpered and 3.3v jumpered boards. Is this expected behavior?
If so then this quote from the hookup guide is confusing: “Notice there are two options for the Pro Micro - 8MHz and 16MHz. It’s very important that you select the Pro Micro option that matches your board’s voltage and speed. This should be listed under the Tools > Processor. For the Qwiic Pro Micro, you will need to ensure that you select the ATmega32U4 (5V, 16MHz).”
I had assumed that the 5v is calls for in the example was just for the purposes of the example where its left at the stock 5v.
I’m hooking this up to a Qwiiic Mux chained with a bunch of SX1509 I/O expanders and was under the impression 3.3 logic was more stable on these components. As I mentioned previously, I’ve got my project working when I use a 3.3v Pro micro (12587), but is there something wrong with these Qwiic Pro Micro’s when I send them 3.3v code, or is the 3.3v jumper just adjust the logic level of the I2C downstream?
It sounds like you have a 16MHz crystal on your board, rather than the 8MHz that comes with a 3.3v board. While officially out-of-tolerance, some Atmels will run at 16MHz with 3.3V, while others won’t. Look carefully at your crystal and it probably reads 16MHz. The bootloader doesn’t care about the voltage, just which Atmel processor you have and what the clock speed is.
Hi Matthew.
If you’ve changed the jumper to make a 5 volt board 3.3 volts, the board is still running at 16MHz so as far as the IDE is concerned, it’s still a “5V 16MHz” Pro Micro.
What you need to do is follow the directions in the [troubleshooting section of the guide for reviving a ‘bricked’ Pro Micro and keep the IDE set to the 5 volt board. It may take several tries to get the board to recover but once you do, it’s good to go as long as you always keep the IDE set to 5V/16MHz.](https://learn.sparkfun.com/tutorials/pro-micro--fio-v3-hookup-guide#troubleshooting-and-faq)