evaporatingt89

Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 11:19 am

Hi,

A quick background, I recently got a raspberry pi 2, and I am a complete beginner. I managed to put Ubuntu MATE 15.04 and so far impressed that a very small thing can do a lot. I would like to make further progressions, I would like to do a project using a raspberry pi 2, but I am really unsure where to start, and how to do it.

Aim: Connect a particulate sensor to this raspberry pi 2, so I can detect the particulate matter in the air pollution. To identify particulate matter (pm2.5) in the air, so I can make people aware where it’s not healthy area/toxic area.

My three main questions:

1) Where can I get a cheap “particulate sensor” for detecting particulate matter (pm2.5) in the air that works with a raspberry pi 2? (I just need a cheap one, it’s just for this project)

2) How do I connect a particulate sensor to a raspberry pi 2?

3) And does it connect through GPIO pins, how?

I hope someone can kindly help me.

Many Thanks,
C

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 11:49 am

cleanair wrote:Hi,

A quick background, I recently got a raspberry pi 2, and I am a complete beginner. I managed to put Ubuntu MATE 15.04 and so far impressed that a very small thing can do a lot. I would like to make further progressions, I would like to do a project using a raspberry pi 2, but I am really unsure where to start, and how to do it.

Aim: Connect a particulate sensor to this raspberry pi 2, so I can detect the particulate matter in the air pollution. To identify particulate matter (pm2.5) in the air, so I can make people aware where it’s not healthy area/toxic area.

My three main questions:

1) Where can I get a cheap “particulate sensor” for detecting particulate matter (pm2.5) in the air that works with a raspberry pi 2? (I just need a cheap one, it’s just for this project)

2) How do I connect a particulate sensor to a raspberry pi 2?

3) And does it connect through GPIO pins, how?

I hope someone can kindly help me.

Many Thanks,
C

Some interesting reading here
The SEEED studio Shinyei PPD42NS dust sensor (http://www.seeedstudio.com/depot/grove- ... -1050.html) comes with a cable wired for +5VDC, GND, and P1. P1 shows >1um particles. The interesting thing is that the PPD42NS also has a pin P2 that shows >2.5um particles. So this allows you to determine if the detected particles are < 2.5um. This is important for health reasons.
I contacted Shinyei. By default P2 is calibrated for > 2.5um. Don't fiddle with the pots. You can change the P2 detection size by changing the input voltage to pin 5. P1 is always >1um. If you look at P1 and P2 on a scope you can see what is happening. If P1 only, then >1um and < 2.5um. If P1 & P2 then >2.5um. Looking at the pulse size ratios of P1&P2 can tell you that you have a mix of particle sizes.

Another interesting thing is that SEEED is not an official distributor of Shinyei. Shinyei has newer versions of the PPD42Nx.
It seems that the detection isn't very reliable when compared to a more expensive sensor:
At first glance, the correlation for the Shinyei sensor seems to be much stronger from PM10 than PM2.5 readings. But, actually, it seems to be even more complicated since during some periods, the correlation to PM10 seems higher while for other periods, correlation to PM2.5 is higher. If this turns out to be true (which will require more data for the confirmation), that would mean that calculating the AQI from a Shinyei sensor could prove to be very arbitratary (see the PM10 vs. PM2.5 analysis).
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 12:01 pm

Thanks for your reply.

So are you saying, if I integrate a cheap particulate sensor, there are high chances of poor accuracy?

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 12:08 pm

cleanair wrote:Thanks for your reply.

So are you saying, if I integrate a cheap particulate sensor, there are high chances of poor accuracy?
that seemed to be the general sweep of the second site that I linked there, it is mentioned in comments on various other pages as well.

It seems likely that the optics on a cheap sensor are unlikely to have the precision needed for accurate 2.5um measurement.
Doug.
Building Management Systems Engineer.

texy
Forum Moderator
Forum Moderator
Posts: 5160
Joined: Sat Mar 03, 2012 10:59 am
Location: Berkshire, England

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 12:14 pm

cleanair wrote:Hi,

A quick background, I recently got a raspberry pi 2, and I am a complete beginner. I managed to put Ubuntu MATE 15.04 and so far impressed that a very small thing can do a lot. I would like to make further progressions, I would like to do a project using a raspberry pi 2, but I am really unsure where to start, and how to do it.

Aim: Connect a particulate sensor to this raspberry pi 2, so I can detect the particulate matter in the air pollution. To identify particulate matter (pm2.5) in the air, so I can make people aware where it’s not healthy area/toxic area.

My three main questions:

1) Where can I get a cheap “particulate sensor” for detecting particulate matter (pm2.5) in the air that works with a raspberry pi 2? (I just need a cheap one, it’s just for this project)

2) How do I connect a particulate sensor to a raspberry pi 2?

3) And does it connect through GPIO pins, how?

I hope someone can kindly help me.

Many Thanks,
C
Please don't multi-post in other sub-forums - keep to one where we can all keep track of the issue. I have deleted the other threads.
Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 4:04 pm

BMS Doug wrote:
cleanair wrote:Thanks for your reply.

So are you saying, if I integrate a cheap particulate sensor, there are high chances of poor accuracy?
that seemed to be the general sweep of the second site that I linked there, it is mentioned in comments on various other pages as well.

It seems likely that the optics on a cheap sensor are unlikely to have the precision needed for accurate 2.5um measurement.
After reviewing my goal, my main objective is to just detect some particles in the air (if there are any). If it can't detect pm2.5 exactly, it's not a problem. My project is mainly for educational purposes, so I really just want to be able to read the particle sensor, and then output on a terminal or write values inside a file etc. This will demonstrate it can detect particles in the air, and this is exactly what I'm trying to achieve.

So will the above sensor, work with a raspberry pi 2, and is it simple to integrate?


Warm Regards,
C

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Thu Sep 17, 2015 4:05 pm

texy wrote:
cleanair wrote:Hi,

A quick background, I recently got a raspberry pi 2, and I am a complete beginner. I managed to put Ubuntu MATE 15.04 and so far impressed that a very small thing can do a lot. I would like to make further progressions, I would like to do a project using a raspberry pi 2, but I am really unsure where to start, and how to do it.

Aim: Connect a particulate sensor to this raspberry pi 2, so I can detect the particulate matter in the air pollution. To identify particulate matter (pm2.5) in the air, so I can make people aware where it’s not healthy area/toxic area.

My three main questions:

1) Where can I get a cheap “particulate sensor” for detecting particulate matter (pm2.5) in the air that works with a raspberry pi 2? (I just need a cheap one, it’s just for this project)

2) How do I connect a particulate sensor to a raspberry pi 2?

3) And does it connect through GPIO pins, how?

I hope someone can kindly help me.

Many Thanks,
C
Please don't multi-post in other sub-forums - keep to one where we can all keep track of the issue. I have deleted the other threads.
Texy
Apologies for that :D

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 18, 2015 9:16 am

cleanair wrote:
BMS Doug wrote:
cleanair wrote:Thanks for your reply.

So are you saying, if I integrate a cheap particulate sensor, there are high chances of poor accuracy?
that seemed to be the general sweep of the second site that I linked there, it is mentioned in comments on various other pages as well.

It seems likely that the optics on a cheap sensor are unlikely to have the precision needed for accurate 2.5um measurement.
After reviewing my goal, my main objective is to just detect some particles in the air (if there are any). If it can't detect pm2.5 exactly, it's not a problem. My project is mainly for educational purposes, so I really just want to be able to read the particle sensor, and then output on a terminal or write values inside a file etc. This will demonstrate it can detect particles in the air, and this is exactly what I'm trying to achieve.

So will the above sensor, work with a raspberry pi 2, and is it simple to integrate?


Warm Regards,
C

This guy seems to have written a fairly well documented process for connecting the sensor to a Pi.
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Sun Sep 20, 2015 7:28 pm

BMS Doug wrote:
This guy seems to have written a fairly well documented process for connecting the sensor to a Pi.
Thank you very much Doug for all the help, I sincerely appreciate it.

One last question I hope, based on all the helpful information you have provided me, I have learnt the SEEED studio Shinyei PPD42NS dust sensor is quite cheap and will most likely be adequate for this prototype project I want to do.

But question is that, can this be directly connected to the PI, or do I have to purchase this Grove Board so that it connects to the PI first?

This mean it would go like this:
PI -> grove board -> grove dust sensor

I'm confused whether the above sensor can directly connect to the PI without the requiring to be connected to the grove board?


Many Thanks,
C

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Mon Sep 21, 2015 3:37 pm

cleanair wrote:
BMS Doug wrote:
This guy seems to have written a fairly well documented process for connecting the sensor to a Pi.
Thank you very much Doug for all the help, I sincerely appreciate it.

One last question I hope, based on all the helpful information you have provided me, I have learnt the SEEED studio Shinyei PPD42NS dust sensor is quite cheap and will most likely be adequate for this prototype project I want to do.

But question is that, can this be directly connected to the PI, or do I have to purchase this Grove Board so that it connects to the PI first?

This mean it would go like this:
PI -> grove board -> grove dust sensor

I'm confused whether the above sensor can directly connect to the PI without the requiring to be connected to the grove board?


Many Thanks,
C
Hmm, It's not as clear from the blog I linked as it seemed to be at first glance.

You won't need the grove board, the Shinyei sensor has digital outputs that the Pi can monitor
1 : COMMON(GND)
2 : OUTPUT(P2)
3 : INPUT(5VDC 90mA)
4 : OUTPUT(P1)
5 : INPUT(T1)・・・FOR THRESHOLD FOR [P2]
The output is stated to be at 4V so a voltage divider is recommended to bring those down to 3V3.

Connect as follows (you may need a breadboard)
Pi Pin 2 (or 4) (5V) connects to Shinyei pin 3 (5V input).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to Shinyei pin 1 (Common).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 16 (GPIO 23) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 2 (output 2).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 18 (GPIO 24) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 4 (output 1).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a Variable resistor, the other end of which connectors to Pi pin 2 (or 4) (5V) and the wiper of which is connected to Shinyei Pin 5 (P2 threshold setting). Adjust the variable resistor to adjust the size of dust particle which triggers P2.

Image
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Mon Sep 21, 2015 3:49 pm

BMS Doug wrote:
cleanair wrote:
BMS Doug wrote:
This guy seems to have written a fairly well documented process for connecting the sensor to a Pi.
Thank you very much Doug for all the help, I sincerely appreciate it.

One last question I hope, based on all the helpful information you have provided me, I have learnt the SEEED studio Shinyei PPD42NS dust sensor is quite cheap and will most likely be adequate for this prototype project I want to do.

But question is that, can this be directly connected to the PI, or do I have to purchase this Grove Board so that it connects to the PI first?

This mean it would go like this:
PI -> grove board -> grove dust sensor

I'm confused whether the above sensor can directly connect to the PI without the requiring to be connected to the grove board?


Many Thanks,
C
Hmm, It's not as clear from the blog I linked as it seemed to be at first glance.

You won't need the grove board, the Shinyei sensor has digital outputs that the Pi can monitor
1 : COMMON(GND)
2 : OUTPUT(P2)
3 : INPUT(5VDC 90mA)
4 : OUTPUT(P1)
5 : INPUT(T1)・・・FOR THRESHOLD FOR [P2]
The output is stated to be at 4V so a voltage divider is recommended to bring those down to 3V3.

Connect as follows (you may need a breadboard)
Pi Pin 2 (or 4) (5V) connects to Shinyei pin 3 (5V input).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to Shinyei pin 1 (Common).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 16 (GPIO 23) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 2 (output 2).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 18 (GPIO 24) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 4 (output 1).
Pi Pin 6 (or 9, 14, 20, 25, 30, 34, 39) (Gnd) connects to a Variable resistor, the other end of which connectors to Pi pin 2 (or 4) (5V) and the wiper of which is connected to Shinyei Pin 5 (P2 threshold setting). Adjust the variable resistor to adjust the size of dust particle which triggers P2.

Image
Thank you, I'll have a go, and report back my progress.

Many thanks for everything.
C

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Mon Sep 21, 2015 3:57 pm

You are welcome, I hope it works for you.
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 12:36 pm

BMS Doug wrote:You are welcome, I hope it works for you.
Hi Doug,

I'm having some trouble understanding how to connect to the GPIO with the breadboard.

Connect as follows (including on a breadboard):
1. Connect Pi Pin 2 or 4 to (5V) – connect this to Shinyei pin 3 (5V input).

2. Connect Pi Pin 6 or any other ground pin - connect to Shinyei pin 1 (Common).

3. Connect Pi Pin 6 or any other ground pin - connect to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 16 (GPIO 23) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 2 (output 2).

4. Pi Pin 6 or any other ground pin - connect to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 18 (GPIO 24) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 4 (output 1).

5. Pi Pin 6 or any other ground pin - connect to a Variable resistor, the other end of which connectors to Pi pin 2 (or 4) (5V) and the wiper of which is connected to Shinyei Pin 5 (P2 threshold setting). Adjust the variable resistor to adjust the size of dust particle which triggers P2.

You have suggested the following below, I understand 1 & 2 quite easily, but 3, 4 and 5 are really confusing me.

For example, on number 2 you suggested to use pin 6 and do x, but how can I use it again on task number 3, 4, 5?


Kind Regards,
H

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 1:22 pm

If you have this style of breadboardImage you can see the internal connections marked (red and black for power and neutral rails, green for each line of 5 connections). The mini breadboard just has groups of 5 lines connected together. Image.

Connect once to pin 6 and then each time pin 6 is mentioned just add a connection to that line on the breadboard.

If you have the larger style of breadboard then connect Pin 2 (or 4) to the red rail and pin 6 to the black rail and use the power and ground from the red and black rails as required within the project.
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 2:26 pm

BMS Doug wrote:If you have this style of breadboardImage you can see the internal connections marked (red and black for power and neutral rails, green for each line of 5 connections). The mini breadboard just has groups of 5 lines connected together. Image.

Connect once to pin 6 and then each time pin 6 is mentioned just add a connection to that line on the breadboard.

If you have the larger style of breadboard then connect Pin 2 (or 4) to the red rail and pin 6 to the black rail and use the power and ground from the red and black rails as required within the project.
Just to be a bit clear, the breadboard I am referring to: http://cdn.instructables.com/F4P/UCSC/G ... .LARGE.jpg

So connect pin 6 on the GPIO header, and then on the breadboard where?

User avatar
rpdom
Posts: 15361
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 2:46 pm

cleanair wrote:Just to be a bit clear, the breadboard I am referring to: http://cdn.instructables.com/F4P/UCSC/G ... .LARGE.jpg

So connect pin 6 on the GPIO header, and then on the breadboard where?
That's the same as the breadboard in Doug's first picture.

Connect a wire from pin 6 on the Pi to one of the holes next to the blue lines marked "-". Then all of the holes along that blue line are connected to pin 6.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 3:36 pm

rpdom wrote:
cleanair wrote:Just to be a bit clear, the breadboard I am referring to: http://cdn.instructables.com/F4P/UCSC/G ... .LARGE.jpg

So connect pin 6 on the GPIO header, and then on the breadboard where?
That's the same as the breadboard in Doug's first picture.

Connect a wire from pin 6 on the Pi to one of the holes next to the blue lines marked "-". Then all of the holes along that blue line are connected to pin 6.
Got it! Thanks so much "rpdom". That great clarity.

May I ask some very amateur questions (just confusing me):

Q1) Above, where Doug mentions "3k3" resistor. Is he referring to a 3.3kOhm? Because I can find 3.3k resisitor, but not 3k3.

Q2) Similar question to above, where Doug mentions "1k2" resistor. Is he referring to a 1.2kOhm? Because I can find 1.2k resisitor, but not 1k2.

Q3) What is a Variable resistor? I'm having trouble finding on google, or anywhere to purchase? Please can you kindly give me a link?

Q4) Is a voltage divider, another name for a resistor? e.g.10k resistor?

Thanks Doug, rpdom for all the help, I really appreciate your patience, guidance, and knowledge sharing. I just want to get this working, and I'll be extremely pleased :-)

C

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 3:52 pm

cleanair wrote:
rpdom wrote:
cleanair wrote:Just to be a bit clear, the breadboard I am referring to: http://cdn.instructables.com/F4P/UCSC/G ... .LARGE.jpg

So connect pin 6 on the GPIO header, and then on the breadboard where?
That's the same as the breadboard in Doug's first picture.

Connect a wire from pin 6 on the Pi to one of the holes next to the blue lines marked "-". Then all of the holes along that blue line are connected to pin 6.
Got it! Thanks so much "rpdom". That great clarity.

May I ask some very amateur questions (just confusing me):

Q1) Above, where Doug mentions "3k3" resistor. Is he referring to a 3.3kOhm? Because I can find 3.3k resisitor, but not 3k3.

Q2) Similar question to above, where Doug mentions "1k2" resistor. Is he referring to a 1.2kOhm? Because I can find 1.2k resisitor, but not 1k2.

Q3) What is a Variable resistor? I'm having trouble finding on google, or anywhere to purchase? Please can you kindly give me a link?

Q4) Is a voltage divider, another name for a resistor? e.g.10k resistor?

Thanks Doug, rpdom for all the help, I really appreciate your patience, guidance, and knowledge sharing. I just want to get this working, and I'll be extremely pleased :-)

C
1. yes, 3.3K ohm is the same as 3K3, in the notation I was using the multiplier is used to mark the decimal point (this makes it easier to tell at a glance the rough value referred to).

2. yes, as above.

3. a variable resistor (also known as a potentiometer) is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

4. a voltage divider is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.



http://www.lifehack.org/articles/techno ... ently.html
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Wed Sep 23, 2015 8:08 pm

BMS Doug wrote:
3. a variable resistor (also known as a potentiometer) is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

4. a voltage divider is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.
Thank you Doug, I'm sure it will be a lot clearer later on, and I'll reflect back on this confusion and laugh at the simpleness.

Q1) But the variable resistor and voltage divider are confusing me now. Do you know where I can buy these two from? (Online retailers or anywhere)

Q2) Having second thoughts now, it seems this Shinyei PPD42NS connecting up is extremely difficult on the PI with the variable resistor and voltage divider stuff.
Would you say this (Compact Optical Dust Sensor – GP2Y1010AU0F) would be more simpler/easier to connect to the Pi or as difficult? I just want to be able to read particulate matter in the air.

Warm Regards,
C

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 25, 2015 7:12 am

cleanair wrote:
BMS Doug wrote:
3. a variable resistor (also known as a potentiometer) is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

4. a voltage divider is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.
Thank you Doug, I'm sure it will be a lot clearer later on, and I'll reflect back on this confusion and laugh at the simpleness.

Q1) But the variable resistor and voltage divider are confusing me now. Do you know where I can buy these two from? (Online retailers or anywhere)

Q2) Having second thoughts now, it seems this Shinyei PPD42NS connecting up is extremely difficult on the PI with the variable resistor and voltage divider stuff.
Would you say this (Compact Optical Dust Sensor – GP2Y1010AU0F) would be more simpler/easier to connect to the Pi or as difficult? I just want to be able to read particulate matter in the air.

Warm Regards,
C

This is fairly basic electronics, not anything too complex.

1. a voltage divider is created by using two resistors (for resistor values for this application see previous posts).
a variable resistor, I don't know where in the world you live but try this link.

2. probably about the same complexity.
Doug.
Building Management Systems Engineer.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 25, 2015 8:58 am

BMS Doug wrote:
This is fairly basic electronics, not anything too complex.

1. a voltage divider is created by using two resistors (for resistor values for this application see previous posts).
a variable resistor, I don't know where in the world you live but try this link.
Awesome, thank you, it's just this is my first time doing electronics.

Do you know of any YouTube videos or pictures that is similar to what I need to do, or shows how to connect it on the voltage divider, and setup the variable resistor on the breadboard? (I am a visual person, this can greatly aid the understanding)

Similarly, how "rpdom" explained the pin 6 thing, I was able to view the image and follow the instruction. I've been Googling and YouTube searching, but the videos I look at, they don't seem relevant.


Thank You

Massi
Posts: 1691
Joined: Fri May 02, 2014 1:52 pm
Location: Italy

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 25, 2015 9:27 am

since you are a visual person, why don't you try to draw your circuit on fritzing.org and post the image?
It will be easier for us to know what you did not understand.

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 25, 2015 7:00 pm

Massi wrote:since you are a visual person, why don't you try to draw your circuit on fritzing.org and post the image?
It will be easier for us to know what you did not understand.
Sounds a good approach. I will have a go drawing.

One question though, above where Doug mentioned: "Connect Pi Pin 6 or any other ground pin - connect to a 3k3 resistor (voltage divider) the other end of which connects to Pi pin 16 (GPIO 23) (or any other GPIO pin of your choice) and to a 1k2 resistor, the other end of which is connected to Shinyei Pin 2 (output 2)."

Can I just use 10km ohm for every resistor, instead of 3k3, or 1k2? I really didn't want to buy a pack of 20 of 3.3k and 1.2k, because I only need like 3 or 4 of each resistor type.

User avatar
davidcoton
Posts: 4180
Joined: Mon Sep 01, 2014 2:37 pm
Location: Cambridge, UK

Re: Raspberry PI 2 Particulate Sensor Project

Fri Sep 25, 2015 10:34 pm

cleanair wrote: Can I just use 10km ohm for every resistor, instead of 3k3, or 1k2? I really didn't want to buy a pack of 20 of 3.3k and 1.2k, because I only need like 3 or 4 of each resistor type.
No. The resistor values are chosen to give the correct division of the voltage (5V in -- 3V3 out). I think you need to find a good basic visual electronics tutorial, before you damage you Pi or the connected equipment. Sorry I've been doing electronics too long to be able to make a recommendation.

If you are going to do any more than one project, buy a starter kit of resistors (look for an E12 kit -- quite enough to start with). It may seem expensive, but you need a range of resistors to experiment with.
Signature retired

evaporatingt89

Re: Raspberry PI 2 Particulate Sensor Project

Sat Sep 26, 2015 10:49 am

davidcoton wrote:
No. The resistor values are chosen to give the correct division of the voltage (5V in -- 3V3 out). I think you need to find a good basic visual electronics tutorial, before you damage you Pi or the connected equipment. Sorry I've been doing electronics too long to be able to make a recommendation.

If you are going to do any more than one project, buy a starter kit of resistors (look for an E12 kit -- quite enough to start with). It may seem expensive, but you need a range of resistors to experiment with.
No, I'm not connecting anything yet, I'm just trying to finalise my shopping list, also until I have fully understood I won't plug anything in.

I'll buy a resistors pack, which I see contain different values. Does it matter whether it's carbon or metal resistors?

Doug, what specific type of variable resistors do I need? There are too many.

Thanks,
C

Return to “Advanced users”