# Bootloading an ATmega32u4 Microprocessor

**URL:** <https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895>\
**Category:** PCB Design\
**Created:** [July 10, 2023, 11:00pm UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895 "2023-07-10T23:00:24Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![copperclaw](https://avatars.discourse-cdn.com/v4/letter/c/7ba0ec/32.png) [@copperclaw](https://community.sparkfun.com/u/copperclaw)\
**Post date:** [July 10, 2023, 11:00pm UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895/1 "2023-07-10T23:00:24Z")

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Hi,

I’m working on a project and have really been struggling to try to get any piece of code to run on a custom ATmega32u4 microprocessor with a custom fully assembled circuit board. I wanted to ask and see if there was any way somebody could help, or provide any assistance.

I’ve been struggling with this for quite some time, any help or guidance would be greatly appreciated.

Thank you in advance

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**Author:** ![jremington](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/jremington/32/6595_2.png) [@jremington](https://community.sparkfun.com/u/jremington)\
**Post date:** [July 11, 2023, 12:04am UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895/2 "2023-07-11T00:04:57Z")

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No bootloader is required if you use an ISP programmer. By far my favorite is this one: [https://www.pololu.com/product/3172](https://www.pololu.com/product/3172)

With a factory fresh AVR processor, you MUST set the fuses to use the appropriate clock source.

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<div class="post-metadata">

**Author:** ![copperclaw](https://avatars.discourse-cdn.com/v4/letter/c/7ba0ec/32.png) [@copperclaw](https://community.sparkfun.com/u/copperclaw)\
**Post date:** [July 11, 2023, 6:40pm UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895/3 "2023-07-11T18:40:59Z")

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I currently am using this:

[https://www.amazon.com/dp/B0885RKVMC?ps … ct\_details](https://www.amazon.com/dp/B0885RKVMC?psc=1&ref=ppx_yo2ov_dt_b_product_details)

should this device work?

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<div class="post-metadata">

**Author:** ![jremington](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/jremington/32/6595_2.png) [@jremington](https://community.sparkfun.com/u/jremington)\
**Post date:** [July 11, 2023, 7:29pm UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895/4 "2023-07-11T19:29:29Z")

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If you can successfully program the ATmega32U4 with that device, then it works.

If you can’t, then take a few moments to post a wiring diagram, describe your setup, the steps you took to program the MCU, and what happens when you try.

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<div class="post-metadata">

**Author:** ![copperclaw](https://avatars.discourse-cdn.com/v4/letter/c/7ba0ec/32.png) [@copperclaw](https://community.sparkfun.com/u/copperclaw)\
**Post date:** [July 11, 2023, 8:47pm UTC](https://community.sparkfun.com/t/bootloading-an-atmega32u4-microprocessor/45895/5 "2023-07-11T20:47:40Z")

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What exactly is a wiring digram in this context? I don’t know if I have access to the wiring of the aspusb uploader.

The setup is n ASPUSB uploader connected to a fully assembled circuit board, code coming from an OSX Ventures. The ASPUSB uploader is the one linked above, but I will link it below for convenience.

[https://www.amazon.com/dp/B0885RKVMC?ps … ct\_details](https://www.amazon.com/dp/B0885RKVMC?psc=1&ref=ppx_yo2ov_dt_b_product_details)

The steps I’ve taken have been using AVRDUDE, I’ve gone through countless tutorials with no success. No clue where I’m going wrong.