marakaci
Posts: 3
Joined: Tue Dec 04, 2018 11:02 pm

Turbidity sensor connection

Tue Dec 04, 2018 11:15 pm

Hi. I'm a noobie.
I've bought a turbidity sensor for my course project
https://www.ebay.com/itm/Turbidity-Tran ... 3834639663
it has quite a poor description and I haven't found tutorials about this model, so I don't really know, how to move futher.


There are 3 pins on the turbidity board. VCC, GND, OUT. What does OUT means?
What GPIO should I connect it to?
What is the type of signal does it produce? Digital or analog? How can I check it?

Can I connect it without resister straight to raspberry?
I don't care about the preciseness of the sensor, I just need to make it show some data)

PhatFil
Posts: 752
Joined: Thu Apr 13, 2017 3:55 pm

Re: Turbidity sensor connection

Wed Dec 05, 2018 1:07 am

OUT will be the data pin, the pin you connect to I suspect an analog input pin, hmm.
with only 1 i/o connection on a digital pin the options are High or low. (on/off) while turbidity (yes i had to look that up), isnt an on/off condition,
So without further digital pins configured to facilitate a more sophisticated coms protocol ie spi or i2c it pretty much has to be an analog output providing a variable voltage output depending on state.

search for how to read a 5V analog signal on a 3.3v pi for the connection, you may find it easier to interface the 3.3v pi to a 5v ADC,, but you will need a Analog Digital Converter.

as its designed for an arduino it may be easier to use an arduino or clone as a slave over serial spi or i2c running a knocked down version of the code for this project https://www.dfrobot.com/blog-679.html that looks like its using the same sensors as you??

marakaci
Posts: 3
Joined: Tue Dec 04, 2018 11:02 pm

Re: Turbidity sensor connection

Wed Dec 05, 2018 11:19 pm

PhatFil wrote:
Wed Dec 05, 2018 1:07 am
OUT will be the data pin, the pin you connect to I suspect an analog input pin, hmm.
with only 1 i/o connection on a digital pin the options are High or low. (on/off) while turbidity (yes i had to look that up), isnt an on/off condition,
So without further digital pins configured to facilitate a more sophisticated coms protocol ie spi or i2c it pretty much has to be an analog output providing a variable voltage output depending on state.

search for how to read a 5V analog signal on a 3.3v pi for the connection, you may find it easier to interface the 3.3v pi to a 5v ADC,, but you will need a Analog Digital Converter.

as its designed for an arduino it may be easier to use an arduino or clone as a slave over serial spi or i2c running a knocked down version of the code for this project https://www.dfrobot.com/blog-679.html that looks like its using the same sensors as you??
Hi. Thanks for your quick reply.
Have I understood you correctly, that I can buy PCF8591 ADC, connect OUT from turbidity to ADC analog input. Connect vcc, gnd from turbidity to raspberry GPIOs, connect vcc, gnd, i2c from PCF8591 to PI GPIOs and I will get things working?


marakaci
Posts: 3
Joined: Tue Dec 04, 2018 11:02 pm

Re: Turbidity sensor connection

Thu Dec 06, 2018 10:46 pm

PhatFil wrote:
Thu Dec 06, 2018 1:19 am
basically yes, https://www.waveshare.com/wiki/Raspberr ... 8591_AD/DA should help..
I got it working.
Thanks for your help

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