3 QRD1114+Button+Arduino+Mini Breadboard+HELP!

Projects General Guidance
1

Hello tinkerers :slight_smile:

I'm working on a project that surpasses my knowledge of electronics, and I need your help!

I connected 1 QRD1114 IR emitted / Phototransistor as per this tutorial, http://bildr.org/2011/03/various-proximity-sensors-arduino/ with the exception that I added a push button. Please consult the image bellow to see my setup:

If the image does not show up in the post, please follow this link http://picpaste.com/pics/qrd1114_Button_Arduino1-01-iLETOM7g.1373309799.jpg

I am not able to figure out the best way to connect 3 QRD1114 on my mini breadboard, along with the push button and required resistors.

The most important aspect for this project is that I need to get independent readings from each QRD1114 unit. I'm guessing that each should be on a different analogue pin, no? Also, the push button should not interrupt any activity or readings from the 3 QRD1114 units. The button should simply be recognized when pushed.

I'm concerned with the proper resistors to use. I'm still a noob with electronics and did not find a way to properly evaluate the resistance needed, taking into consideration the QRD1114 specs https://www.sparkfun.com/datasheets/BOT/QRD1114.pdf

In short, HELP!

Thank you for your time and I really look forward to your input!

Heff

PS: Yes, I did search the web, the Arduino and bildr forums before posting this, but did not find the information that I needed.

2

Each QRD1114 has two terminals connected to Ground, one connected through a 200 Ohm resistor to +5, one connected through a 5.7K resistor to +5 and also to an analog input. The only difference between your four units would be which analog input they connect to.

3

Hi John,

Thank you for taking the time to reply!

I want to make sure that I understand.

johnwasser:
"The only difference between your four units would be which analog input they connect to"

Can I use the resistor setup used for one QRD1114 for all three units and simply connect each unit on a different analogue pin? So, only one 200 Ohm + one 5.7K resistor for all three QRD1114 units? A serial connection?

2 resitors: 200 Ohm + 5.7K
3 QRD1114 units on 3 analogue pins

Or

Each single QRD1114 unit needs to have the resistor combination of one 200 Ohm + one 5.7K and each unit connected to a unique analogue pin? A parallel connection?

6 resistors: three 200 Ohm + three 5.7K
3 QRD1114 units on 3 analogue pins

Thank you again :slight_smile:

Heff

PS: I just edited my reply to correct a few silly typos! Sorry :smiley:

4

Heff:
Each single QRD1114 unit needs to have the resistor combination of one 200 Ohm + one 5.7K and each unit connected to a unique analogue pin? A parallel connection?

6 resistors: three 200 Ohm + three 5.7K
3 QRD1114 units on 3 analogue pins

Yes, that second one. Each unit uses two resistors. One (200 Ohm) provides current limiting for the LED. The other (5.7K) is a pull-up for the phototransistor. As the amount of detected light changes so does the current running through the phototransistor. The voltage at the terminal will depend on the current. The analog input is used to measure that voltage.

5

Hi John!

Thank you very much for the prompt and crystal clear follow up :slight_smile:

I'll give it at go after some coffee in the morning. Only after coffee, to make sure all is good on my mini breadboard.

Sending good Karma your way XD

Heff