# ADS1115 ceramic capacitor: decoupling / noise removal?

**URL:** <https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854>\
**Category:** Hardware\
**Created:** [23 April 2023 17:58 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854 "2023-04-23T17:58:49Z")\
**Posts on this page:** 8\
**Page:** 2

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**Author:** ![hotNipi](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/hotnipi/32/383_2.png) [@hotNipi](https://discourse.nodered.org/u/hotNipi)\
**Post date:** [25 April 2023 19:05 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/21 "2023-04-25T19:05:22Z")

</div>

Just asking cos pressure + heat is a bomb by nature..

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<div class="post-metadata">

**Author:** ![WBr](https://avatars.discourse-cdn.com/v4/letter/w/b3f665/32.png) [@WBr](https://discourse.nodered.org/u/WBr)\
**Post date:** [25 April 2023 19:14 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/22 "2023-04-25T19:14:36Z")

</div>

That is true! but I am only speaking about the range between 1000 hPa and 1200 hPa

so from 1 bar (atmospheric pressure) to 1.2 bar (0.2 bar overpressure - if - the conditions are unfavourable)

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<div class="post-metadata">

**Author:** ![WBr](https://avatars.discourse-cdn.com/v4/letter/w/b3f665/32.png) [@WBr](https://discourse.nodered.org/u/WBr)\
**Post date:** [25 April 2023 19:26 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/23 "2023-04-25T19:26:14Z")

</div>

speaking of pressure...  
Is this the correct way to calculate pressure from the voltage in ADS1115?

spec sheet says: ` VOUT = VOFF + (sensitivity x P)`

Vout is measured with ADS1115  
Voffset is 20 mV  
Sensitivity is 1.2 mv/kPa  
P is the desired value we need to calculate (in kPa)

So I thought `P=((V_out-20)/1,2) in kPa`  
But I feel like I am missing something...

```auto
[{"id":"40f5c6c11104d810","type":"ads1x15_i2c","z":"6bd58bfbd46a21f9","property":"payload","name":"","i2c_device_number":1,"chip":"0x01","i2c_address":"0x48","inputsForChannel":"differential","singleEndedChannel0":true,"singleEndedChannel1":true,"singleEndedChannel2":true,"singleEndedChannel3":true,"differentialChannel0_1":true,"differentialChannel0_3":false,"differentialChannel1_3":false,"differentialChannel2_3":false,"samplesPerSecond0":"920","samplesPerSecond1":"128","progGainAmp":"4096","x":890,"y":2780,"wires":[["6b76245c13fa40dc"]]},{"id":"8ae074915f170c71","type":"inject","z":"6bd58bfbd46a21f9","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":720,"y":2780,"wires":[["40f5c6c11104d810"]]},{"id":"6b76245c13fa40dc","type":"change","z":"6bd58bfbd46a21f9","name":"change payload with differential value","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload[\"/dev/i2c-1\"].ads1115[\"0x48\"].differential.channel_0_1.miliVolts","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":1150,"y":2780,"wires":[["4418c5a1e79eab36"]]},{"id":"4418c5a1e79eab36","type":"function","z":"6bd58bfbd46a21f9","name":"P=((V_out-20)/1,2) in kPa","func":"msg.payload = ((msg.payload - 20)/1.2);\nreturn msg;\n\n//P=(V_out-20)/1,2 in pKa","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":1450,"y":2780,"wires":[["c0d2cafdbc2cacba"]]},{"id":"c0d2cafdbc2cacba","type":"debug","z":"6bd58bfbd46a21f9","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":1670,"y":2780,"wires":[]}]

```

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/0/b/0ba779ad9e26842151543f9a48034de47e0637c2.png)

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/1/8/186fe24640c102718a87fec9ea4c19d3d8865ddf.png)

```auto
msg.payload = ((msg.payload - 20)/1.2);
return msg;

```

> **[MPX53.pdf](https://www.nxp.com/docs/en/data-sheet/MPX53.pdf)**
>
> 255.12 KB

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/6/d6399f14c8b45b8011611d2fe18b5ce1e4beea3e.png)

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/c/d/cd87908294919ddc2cc4aed62d4caeac8a35c82b.png)

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<div class="post-metadata">

**Author:** ![iiot2k](https://avatars.discourse-cdn.com/v4/letter/i/8baadc/32.png) [@iiot2k](https://discourse.nodered.org/u/iiot2k)\
**Post date:** [25 April 2023 20:16 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/24 "2023-04-25T20:16:24Z")

</div>

I developed the ads1115 node:

> **[node-red-contrib-iiot-rpi-ads1115](https://flows.nodered.org/node/node-red-contrib-iiot-rpi-ads1115)**
>
> A Node-Red node for ads1115 analog to digital converter

In this node you can set the read cycle time.  
I have also add example for scaling in function node.  
Select adc input range 256mV.  
20..90mV=0..50kPa  
var pressure = scale(msg.payload[0], 20, 90, 0, 50);  
Hope, that help you.

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<div class="post-metadata">

**Author:** ![WBr](https://avatars.discourse-cdn.com/v4/letter/w/b3f665/32.png) [@WBr](https://discourse.nodered.org/u/WBr)\
**Post date:** [25 April 2023 21:26 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/25 "2023-04-25T21:26:24Z")

</div>

Will keep that node in mind. First need to let everything work on the other node as i have more flows with that one used 🙂

But thank you!

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<div class="post-metadata">

**Author:** ![WBr](https://avatars.discourse-cdn.com/v4/letter/w/b3f665/32.png) [@WBr](https://discourse.nodered.org/u/WBr)\
**Post date:** [1 May 2023 12:51 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/26 "2023-05-01T12:51:09Z")

</div>

Any idea if I am missing something in the conversion with the ADS1115?

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<div class="post-metadata">

**Author:** ![WBr](https://avatars.discourse-cdn.com/v4/letter/w/b3f665/32.png) [@WBr](https://discourse.nodered.org/u/WBr)\
**Post date:** [2 June 2023 10:55 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/27 "2023-06-02T10:55:53Z")

</div>

Still stuck on this. Is it better to measure this on an arduino? Has my ADS1115 any impact on the way I calculate it...?

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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:** [1 August 2023 10:56 UTC](https://discourse.nodered.org/t/ads1115-ceramic-capacitor-decoupling-noise-removal/77854/28 "2023-08-01T10:56:22Z")

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