Multiple sensor project - Page 1
Forum section: electronics / projects

author: LatvianOnJuice
author_rank: Contributor
timestamp: September 02, 2015, 12:13:17 pm
content: Hello, everyone!I am writing this post to ask for your help. I am doing a project in its very early stages. The project is basically to measure the temperature, pH, humidity and light sensitivity of the soil of a plant / surroundings (depending on the specific resistor).I wanted to know if you have any knowledge about what type of sensors are best to use and how to display the values / statistics the best way.My thinking is to use an Arduino board which could help controlling the sensors and a shield, giving a wifi connection (thus a mobile application could be programmed, indicating all of the results).I know for now it's just a cluster of ideas, but if you know anything / have any kind of experience relating sensors and wifi connections, please, let me know.Thank you in advance!All the best!P.S. Don't tell me to google everything, because this forums is a far greater resource of great electronic minds than anywhere, so let's live up to the expectations

author: kripton2035
author_rank: Super Contributor
timestamp: September 02, 2015, 12:22:42 pm
content: esp8266 (model 07 or 12 so you have enought I/O) as a controller (arduino + wifi in the same chip),DHT22 as a temp/humidity sensor, and any LDR/photodiode for light sensorfor the pH I don't know.

author: LatvianOnJuice
author_rank: Contributor
timestamp: September 03, 2015, 11:32:40 am
content: Alright! Thank you both so much for the info! Now I have reconsidered - due to the size and cost, I would much rather build the device with a bluetooth module. The Cypress Bluetooth that evb149 showed seemed to be more than enough for the general proof of concept that I want to make. Plus, the obvious benefits of having a much longer battery life. PLUS, the benefit of having the operating voltage of 1.5v instead of 9V (a block battery, which would add extra weight and space).Now I am trying to search for the most suitable sensors for the bluetooth module + trying to figure out how to program and display the results (an app / pc software).Other than that, I still have about 19 weeks to finish the project, which means that including the delivery time of the parts, I should have more than enough time to build, test and improve the device, if necessary.

author: LatvianOnJuice
author_rank: Contributor
timestamp: September 03, 2015, 12:32:28 pm
content: This looks to me like a very basic system, as there is no feedback (at least I don't require any):Power source (most likely a AAA 1.5v battery) -> all sensors in parallel -> some adjustment / conversion / control circuitry (I am not sure about this just yet) -> bluetooth module -> connection to a PC / mobile app.Either way, the coding part of the PC / app, is what worries me the most, hahaBut hey - live and learn, right?

author: jay
author_rank: Regular Contributor
timestamp: September 03, 2015, 02:33:54 pm
content: Light sensors are often sensitive to all visible light.. Some of them are more sensitive to green than other, but I suppose it's done by adding a filter. The thing is that plants reflect green and use only a narrow band of blue and a bit wider band of red light for photosynthesis, so the ambient light sensors etc give you readings that tell nothing about the amount of light the plant "sees". RGB ambient light sensors (ALS) are available so maybe using only R and B channels would work.Temperature and relative humidity are easy.. There are many good sensors with I2C interface.Soil / water pH and soil moisture (hmm, not mentioned in the OP) are the trickier ones, especially pH, but I'm no expert. Actually aiming at any absolute values is probably outside the feasible range for a small hobby project.Please keep us posted on the progress.. I've thought of building something similar (well, actually I already did years ago but in the end only temperature and relative air humidity worked well).

author: LatvianOnJuice
author_rank: Contributor
timestamp: September 04, 2015, 07:30:23 pm
content: I have decided to use Arduino Uno as my microcontroller (just ordered it + a 9V battery holder and a small breadboard).What I was told by my client is that the size does not matter THAT much. Therefore, I have instructed my team to go with the Uno as our choice of uC (some of the members have worked with those + they are very user-friendly and compatible with many different types of parts).Now what is left with regards to ordering parts are the following parts:-Bluetooth module (several options here: I'm considering the CYBLE-022001-00, but not sure about the compatibility, or the HC-06, which seems quite simple to use + perfectly compatible with the Uno);-Temp + humidity sensor & Light sensitivity sensor.Still doing research, but it all seems to be coming to an end regarding choosing parts.

author: LatvianOnJuice
author_rank: Contributor
timestamp: September 17, 2015, 10:42:48 am
content: Here's a little update for you guys (for those, who are interested):The decisions have been made with regards to component selection. For the first prototype, the team isn't concerned THAT much about size and cost, since we have a supplier. Thus, for the first product, the device will consist of:-9V battery to power the uC;-A little mechanical power switch;-Arduino Uno, as the main microcontroller;-HC-05, as the BLE module;-DHT11, as the humidity & temperature sensor;-BH1750 for light intensity sensing;In the future, though, if we are able to make a nice working device, we will reduce the size of the uC. That would be done by programming an 8-pin ATtiny chip using the Arduino Uno (the size of the entire product shrinks considerably).A mobile application is being programmed as I am typing this post, and at the moment I can only allowed to show you these screenshots (see attachments), which depict the very basic of the basics, haha.As for the project itself - I am learning so much and am so glad I can be a part of it.

author: LatvianOnJuice
author_rank: Contributor
timestamp: October 07, 2015, 12:14:58 pm
content: Update: looking for advice!!!I would like to have this device operated by a battery. The Arduino Mini Pro 3.3v / 8MHz requires (obviously) a 3.3V source. Initially I thought of getting a coin battery (a CR1616, for instance), however I realized that the little CR1616 does not provide enough power.The goal is to have as small and as accessible batteries as possible. The coin batteries would be great, however they lack the power, whereas, say, 2 AAA batteries are relatively large in size. Any recommendations? Perhaps a small boost converter that is connected to a single AAA battery is a possibility?I'd love to hear suggestions. And again - thanks in advance!

author: LatvianOnJuice
author_rank: Contributor
timestamp: October 07, 2015, 03:11:19 pm
content: In other words, the device is something very similar to this:http://www.parrot.com/nl/producten/flower-power/This one is powered by a single AAA battery.