Help with I2C connection

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juju01
 
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Help with I2C connection

Post by juju01 »

I am trying to connect my sensirion sps30 dust sensor to the adafruit QT 3V to 5V Level Booster Breakout on I2C. I will need to connect both pins 4 & 5 on the sps30 to ground. I am not entirely sure how to combine the 2 pins to the ground input of the level booster! A rather basic question! Any ideas?

Inkedsps30_i2c_v2.jpg
Inkedsps30_i2c_v2.jpg (33.42 KiB) Viewed 172 times

jst connector on sps30
pins.jpg
pins.jpg (16.04 KiB) Viewed 172 times

level booster ( connecting to the 5v side)
3vto5v.jpg
3vto5v.jpg (32 KiB) Viewed 172 times

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dastels
 
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Re: Help with I2C connection

Post by dastels »

First of ALL grounds should connect together unless you're using isolation of some sort, e.g. an optoisolator.

For those two ground pins, just connect them both to ground.

Now, exactly what hardware do you have, and how do you have t connected?

Dave

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juju01
 
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Re: Help with I2C connection

Post by juju01 »

Hi Dave

Yes I am looking to do what you suggest - connect all grounds. I havent connected anything yet.

I am looking to connect the sensirion sps30 dust sensor to the adafruit 3v-5v booster on a raspberrypi. The plan is to do this:

sps30 --> 3v -5v booster -- use qwiic connection to --> raspberrypi qwiic hat.

So I am just confused how to connect the 2 grounds on the sps30 to the 5v booster ( as stated in my original question ).

V

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dastels
 
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Re: Help with I2C connection

Post by dastels »

What sensor board? What 3v-5v "booster"?

If you don't answer my questions, there's not much I can do to help.

Dave

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juju01
 
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Re: Help with I2C connection

Post by juju01 »

dastels wrote: Tue Mar 14, 2023 5:54 pm What sensor board? What 3v-5v "booster"?

If you don't answer my questions, there's not much I can do to help.

Dave
Pardon me - I thought all that info is already up there. Perhaps I misunderstand your question.

Sensor board - Sensiron SPS30 https://www.sparkfun.com/products/15103
What 3v-5v "booster"?
Adafruit QT 3V to 5V Level Booster Breakout - STEMMA QT / Qwiic
https://www.adafruit.com/product/5649

On Raspberrypi 4b.

Is this the info you were looking for?

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dastels
 
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Re: Help with I2C connection

Post by dastels »

That's it. Thanks.

According to the docs for the sensor:
The SPS30 requires a 5V power supply, but can work with 3.3V and 5V microcontrollers. The logic is 5V and 3.3V tolerant.
So you shouldn't need the booster.

As for grounds, they get connected together. All grounds MUST be connected together. That establishes a common understanding of all other voltages/signals. What about it is confusing? the electrical connection? How to connect them physically?

Dave

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juju01
 
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Re: Help with I2C connection

Post by juju01 »

The sensor itself requires a 5V supply. It's the SDA/SCL pins that are 5v/3v tolerant.
20GtKo1A.png
20GtKo1A.png (173.49 KiB) Viewed 131 times

I realize I can connect everything directly to the pi4 pins, but I am looking to use a stemma qt adapter on the Pi to manage all my sensor connections. I have three other sensors, all using the stemma interface so makes it cleaner. That's why I decided to use the Booster, which also has the stemma connector.

https://www.adafruit.com/product/4688
4688-00.jpg
4688-00.jpg (617.45 KiB) Viewed 131 times


My confusion is how to physically connect the two ground pins ( pin 4 /5) to the ground on the booster.

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dastels
 
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Re: Help with I2C connection

Post by dastels »

Yeah, that's probably the safe route for the Pi.

How are you connecting the sensor cable to the I2C boost? The boost has a ground pad on each side which are connected together.

Dave

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juju01
 
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Re: Help with I2C connection

Post by juju01 »

The boost has a ground pad on each side which are connected together.
This answers my question. Thanks

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