# Atmega328p with ADXL345

**URL:** <https://community.sparkfun.com/t/atmega328p-with-adxl345/33088>\
**Category:** PCB Design\
**Created:** [June 21, 2016, 6:50am UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088 "2016-06-21T06:50:59Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![re4mat0r](https://avatars.discourse-cdn.com/v4/letter/r/edb3f5/32.png) [@re4mat0r](https://community.sparkfun.com/u/re4mat0r)\
**Post date:** [June 21, 2016, 6:50am UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088/1 "2016-06-21T06:50:59Z")

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Hi. I am trying to build a custom sensor board to connect several sensors to Atmega328p microcontroller.

If anyone can help me and look to the schematics, maybe point some errors, I would really appreciate it.

It is ADXL345 connected to Atmega328p, also a slot for DS18B20 digital thermometer. I have several pads connected to control LEDs with PWM and one pad for interrupt input.

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**Author:** ![skimask](https://avatars.discourse-cdn.com/v4/letter/s/f6c823/32.png) [@skimask](https://community.sparkfun.com/u/skimask)\
**Post date:** [June 21, 2016, 12:44pm UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088/2 "2016-06-21T12:44:58Z")

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No decoupling caps.

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**Author:** ![InactiveUser001](https://avatars.discourse-cdn.com/v4/letter/i/46a35a/32.png) [@InactiveUser001](https://community.sparkfun.com/u/InactiveUser001)\
**Post date:** [June 25, 2016, 9:28am UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088/3 "2016-06-25T09:28:38Z")

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Where does “Res” go thats on R2? I cannot see another reference to it.

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**Author:** ![davep238](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@davep238](https://community.sparkfun.com/u/davep238)\
**Post date:** [June 25, 2016, 5:41pm UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088/4 "2016-06-25T17:41:15Z")

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> mattylad:  
> Where does “Res” go that’s on R2? I cannot see another reference to it.

RES goes to C2. According to its datasheet,the ADXL345 can't have more than 3.9v max on its pins. The micro is a 5 volt part, so its output HI voltage (logic '1') will be 5 volts. The ADXL345 will be damaged or destroyed by connecting its pins directly to the micro. Can you lower the micro's power supply to 3.3volts?

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**Author:** ![InactiveUser001](https://avatars.discourse-cdn.com/v4/letter/i/46a35a/32.png) [@InactiveUser001](https://community.sparkfun.com/u/InactiveUser001)\
**Post date:** [June 27, 2016, 7:04am UTC](https://community.sparkfun.com/t/atmega328p-with-adxl345/33088/5 "2016-06-27T07:04:53Z")

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So it does, if its only there why not simply connect it up lol