Hi,
I need a BOM of Arduino Pro Micro. For reference, plz check the link below. If BOM is not possible then at least the exact part number of microcontroller that has been used in pro micro. The reason for that is to avoid signature errors while uploading the bootloader. I faced this issue many times so I want to know what is an exact part number used in it. Thanks
Thanks for posting!
The exact part number for the microcontroller used on the Pro Micro is ATMEGA32U4-MU.
We don’t carry them on our site, but Digi-Key or Mouser would have them. 
Hi @TS-Chris
Thanks for the reply. I have one more question regarding the schematic of Arduino pro micro. The components used in Sparkfun and the official Arduino pro micro have a huge difference in terms of quantity. I mean, the Sparkfun schematic contained roughly 19 components while the official schematic contained so many extra components. I am curious if this will affect the bootloader or any other feature of Arduino pro micro. Also, uploading the bootloader to Sparkfun pro micro is same like any other Arduino or Sparkfun have their own bootloader due to simplest schematic.
Thanks
SparkFun’s Pro Micro IS the official Arduino Pro Micro. Not sure what you’re looking at but ours is the original.
We do use a customized bootloader based on the Leonardo bootloader but it’s included with the Arduino IDE as long as you have our board files installed. Shouldn’t make any difference in how you burn the bootloader to the board.
Ok, Thanks
Can you provide me complete BOM?
Is it possible?
I do not have a BOM for you but the schematic on the product page should have all the information you need om parts.
Hi @TS-Chris
I am using an Arduino pro micro from Sparkfun but unfortunately, due to some reasons. I have to change its microcontroller which is ATMEGA32U4-MU.
But the issue is this specific number is not available in stock on main suppliers or even the manufacturer. So can I replace it with some other part number with the same package like ATMEGA16U4-MU or ATMEGA32U4-AU or any other same chip.
Thanks
You will have to check the data sheets for the different parts to make sure the pin layout is the same.
Hi @TS-Chris
I talked with the microchip representative and they recommended ATMEGA16U4-MU which has the same pin number and package except it has lower memory. Now my question is, Can I upload the bootloader to this ATMEGA16U4-MU or there will be some signature issue. Thanks
Unfortunately I don’t have an answer to your question, we have not tried to put the bootloader on this part before so we’re not able to tell you if you’re going to have issues or not.
Hi TS-Chris
I am having an issue regarding the USB connection of pro micro. I did the following steps but no success so far.
1: Installed board file into Arduino IDE using board manager.
2: Prepared Arduino as ISP and connect with pro micro.
3: Upload the ISP example program to Arduino UNO
4: Connect Pro micro using ICSP pins to the Sparkfun pro micro.
5: Choose Board Sparkfun pro micro 5V 16Mhz and burn the bootloader
6: Now connect USB and computer do not detect it. Except it gives an error in the device manager.
Unknown USB Device(Device Descriptor Request Failed)
I also tried to upload the bootloader by selecting Arduino Leonardo as a board but still no luck. Plz, help me to solve this. Thanks
This is on a board you made yourself, correct?
It’s possible there’s an error in your board somewhere, or you have a bad connection somewhere causing issues. It could also be that the bootloader was created for a different IC and doesn’t work on the one you have on your board. Unfortunately there isn’t really any way for me to tell exactly where the problem might be. 
Yes, It is correct that I made this board.
1: I don’t think so there is a bad connection while uploading the bootloader otherwise bootloader does not succeed.
2: I noticed one thing, the board which has no bootloader and with bootloader have the same issue. When I plugged in USB, the window tries to connect it for just a moment, and when I check in device manager. I found this error in both cases. I think detection of USB has nothing to do with the bootloader. Am I right?
3: I used Atmega32U4, the same chip that is used in Sparkfun pro micro.
Also, if you can guide me where I can find bootloader files which Sparkfun created for pro micro and its proper way to upload using Arduino As ISP
Here is the schematic diagram of the USB C connection with pro micro.
Your schematic shows 5k1 series resistors in D+ and D-. These should be 22 ohms instead.
/mike
I followed this schematic. Plz, check the schematic under the document tab.
It looks like the schematic is wrong, we actually put 22 ohm resistors in R8 and R9. I’ll ask someone to get that corrected.
Hi @TS-Chris
If I change the resistors with 22 ohms. Will it work?
Also, Is it possible if I completely remove the resistors just for testing. I think it will not damage the data lines.
I removed 5.1k resistors in the data line and short their pad. It started working. I uploaded the program and now it works perfectly. Thanks for all your help.