# Can't get MCP4725 (I2C) to work

**URL:** <https://discourse.nodered.org/t/cant-get-mcp4725-i2c-to-work/44667>\
**Category:** Hardware\
**Created:** [24 April 2021 19:00 UTC](https://discourse.nodered.org/t/cant-get-mcp4725-i2c-to-work/44667 "2021-04-24T19:00:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![fjmhoogl](https://avatars.discourse-cdn.com/v4/letter/f/a9a28c/32.png) [@fjmhoogl](https://discourse.nodered.org/u/fjmhoogl)\
**Post date:** [24 April 2021 19:00 UTC](https://discourse.nodered.org/t/cant-get-mcp4725-i2c-to-work/44667/1 "2021-04-24T19:00:26Z")

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Dear all,

I am trying to hook up a MCP4725 (12-bit DAC) breakout board to the I2C bus of my Raspberry.  
No matter that I do in Node-RED, I cannot get it to accept commands and output a voltage corresponding to msg.payload.

I have two of those boards, one configured for I2C address 0x60 and one for 0x61.

i2cdetect can see both of the boards (I connect one at a time) and reports back the right address.  
At least: when Node-RED is _not_ running. As soon as it runs, I2C ports 0x3-0x77 are all reported as being occupied, even if I have zero devices on the I2C bus.

Can anyone tell me what is going on here?? Any suggestions are very much appreciated.

FYI: the node I'm using for connecting to the MCP4725 is ncd-red-mcp4725, v 1.0.4.

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<div class="post-metadata">

**Author:** ![fjmhoogl](https://avatars.discourse-cdn.com/v4/letter/f/a9a28c/32.png) [@fjmhoogl](https://discourse.nodered.org/u/fjmhoogl)\
**Post date:** [25 April 2021 13:57 UTC](https://discourse.nodered.org/t/cant-get-mcp4725-i2c-to-work/44667/2 "2021-04-25T13:57:01Z")

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Problem solved.  
It turned out I had 2 different types of I2C nodes in the palette at the same time.  
Apparently, that won't work.  
After a full reinstall of Node RED, and installing only the MCP4725 library, all worked fine.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [24 June 2021 13:57 UTC](https://discourse.nodered.org/t/cant-get-mcp4725-i2c-to-work/44667/3 "2021-06-24T13:57:16Z")

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