#322 12 Light Sensors Tested: Measuring Light with Microcontrollers (Arduino or ESP8266, ESP32)

browsing through my collection of sensors I found quite a few which deal with measuring of light today we will have a look at these sensors bring them in some order and test them in the end you should be able to decide which sensor is best for your project pretty youtubers here is the guy with the Swiss accent with a new episode and fresh ideas around sensors and microcontrollers remember if you subscribe you will always sit in the first row in my last video we covered current sensors there we mainly have to distinguish between DC and AC currents today we deal with light which is more complicated because we have many sorts of light so we will look at all sensors I have in my boxes for sure there are much more available please comment on your finds together we are stronger the focus is on sensors available on Aliexpress and as breakout ports we will classify the available sensors according to the purpose and we will test them in the end you should be able to select the right sensor and know how to use it when we talk about light we have to speak about wavelength in video number 269 we used a spectrometer to visualize the visible and IR light this sensor captures all wavelengths from UV to IR in one scan because it is clumsy relatively expensive and very directional it's not a useful sensor for our daily projects but it will be helpful for comparison and understanding today's selection covers the following areas RGB sensors Lux sensors UV sensors IR sensors and proximity and gesture sensors the first sensors try to detect the color of the light source the source of the light by the way can be active or passive active means that the source creates light like a bulb or an LED and passive means that the light is reflected it the sensors cannot distinguish between these two light sources to roughly detect the color of light it is only necessary to measure at three wavelength red green and blue this is what these sensors - in this category I found the following sensors the TCS 3200 is a programmable color light - frequency converter which means it outputs a variable frequency signal and our MCU has to measure the frequency to get the value a little bit more complicated than just read an analog value the sensor consists of 64 diodes 16 of each value and the sketch shows us the respective values for red green blue and clear we need 5 pins to connect the chip here we see the sensitivity curve of the different photo diodes in a small test I show you why it is essential to look at such diagrams if I take an IR diode and illuminate the sensor all four values increase not good they should not react because they are not red green or blue if we have a closer look at the diagram from before we see the reason all photo diodes have their highest sensitivity in infrared the supplier should have added an IR filter but we can fix it an add one typically used in CCTV cameras it can be switched on and off which is quite handy if we switch it off we see similarly high values in all channels as without it if we switch it on these values are much lower cool one thing has to be clear this Center is only sensitive in 3 particular wavelength if a light source emits on a wavelength in between it is probably not seen or detected on two channels let's check it out with these 4 diodes I first check their real spectrum using the spectrometer the blue diode has a wavelength of 460 in 520 yellow 590 and red 630 nanometers so yellow is between red and green now let's check the values of the TCS 3200 I did not like the sketches and libraries I found on the Internet this is why I created my own it reads the time between two pulses using the pulse in function then we can calculate the frequency and normalize the color values and set the highest Valley to 100 like that it is easier to see if the sensor works Green is okay red is okay and blue is detected - yellow is as expected caught in the red and in the green Channel but closer to red so this sensor works fine and can distinguish differently colored things it also comes with 4 white LEDs for illumination because we can we also check their spectrum they emit a lot of blue so pay attention if you use them a white sheet of paper seems to be blue these are the LED panels by the way have a completely different spectrum similar sensors from the same company are the two I square C sensors the TCS 34:14 and the TCS 34 725 both have 4 channels with 4 ADCs and an I square C interface this is easy to use and faster than the frequency signal of the TCS 3200 we also get a library and a sketch for both the most significant difference between the two is the built-in IR filter for the TCS 34 725 however the TCS 34:14 is much more expensive than the other two so the TCS 34 725 seems to be the better choice an interesting alternative is the is l-29 125 it also has an i square c interface and a built-in IR filter it has no Clear Channel typical applications for the last three sensors are color correction in display back lights or other colored illuminations so they should be suitable for many of our color experiments I'm not sure which sensors are also suitable for outdoor usage in full Sun the is l-29 125 for sure needs a strong ND filter because it is too sensitive for bright Sun by the way I printed these small pieces to stick the IR filter to the sensor for my tests you also get many other IR filters because they are widely used now we leave the color and go to the illuminance which is measured in Lux it should show the light intensity as perceived by the human eye this is why it measures with a standard human brightness perception such sensors are widely used in photography to determine the aperture and time for taking pictures I have here a cheap looks meter to compare the sensors and I have an additional plan last year I tried to steer our awning using open weather map torque I wanted to extend the awning if a lot of sunlight is expected to keep the inside temperature down unfortunately I was not successful because the weather data was not exact enough and my wife made quite a few jokes about that fact and my engineering capabilities this is why I have to fix it before this summer a connected Lux meter should do the job I found the following selection of Lux sensors in my boxes a pH 1758 ESL 2561 and 80 SL 25 91 to be complete I also add an LDR and a photo transistor as a rudimentary Lux meter let's start with the bee 1750 it is a simple photodiode an ADC and an eye square see interface the spectral response as expected covers the visible wavelength its range is from 1 to 65535 flux what does this mean here I have a table with looks values of typical situations according to this table this sensor should work in daylight till the dusk but how does it compare with my looks meter I try three different light levels and you can't compare the readings there is a clear correlation I do not know which one is right but I tend to believe the unity device is closer keep also in mind that the difference compared to the possible light levels we saw in the table before is small next I try the TSL 2561 it has no IR filter but a second channel for the IR illumination also here you see a difference and a clear correlation the TSL 25:9 is a similar chip if we look at the homepage of AMS which bought Telos in 2011 we see that both should not be used anymore for new designs but they are still sold in different versions on different platforms LD arse or light dependent resistors are cheap and straightforward parts to detect light levels even cheaper is to subscribe to the channel or to like the video but it makes a big difference for me anyway together with a two point two kilo ohm resistor it produces different voltages if it's covered or not you only need to connect it to an analog input and program a threshold in your sketch please keep in mind that the resistance is high when the light level is low LDRs are not precise nor is their range big the same applies to phototransistors I have here one with an IR filter the diagram is the same as with the LDR and its reaction is also somehow similar if you want to detect I are only the phototransistor with an IR filter is the better choice for example I built a small device for my brother to supervise the error led of its heating system as soon as it is on the esp8266 sends a message and he can react before the house becomes cold now we come to a particular part of the spectrum ultraviolet here I have the ml 85 11 UV sensor it has an analogue output by the way here we see something also other breakout ports use they offer a three point three and a five volt pin I used an ESP 32 for all tests so I connected the 3.3 volt pin the ml 85 11 also is a straight forward sensor it just contains a UV photodiode and an amplifier and it measures UVA and UVB light the output voltage without UV light is 1 volt I use a special UV flashlight for the test you see that my overhead light does not have a lot of UV content the voltage is 1 volt as soon as I move my flashlight closer to the sensor we see an increase in the output voltage also here you need to use an analog input of a microcontroller why detect UV because it would be interesting to see how the UV level behaves around our homes like that you can decide how much Sun cream you have to apply before you leave your house for example on the other side of the spectrum is infrared light it is widely used by makers and you find a few videos on this channel about this topic as we saw some of the above sensors are sensitive to IR without the filter they can also be used to detect IR besides that I want to mention a special IR sensor the TSS opie 18:38 it is used for IR remotes and it's speciality is that it detects only modulated infrared in this case it only detects IR which is switched on and off with the frequency of 38 kilohertz this is done to prevent that pure sunlight can switch your TV on the next sensors are a little special proximity and gesture sensors I include them here because they also measure light and one even has a built in RGB sensor I found an apt s 99 60 and an AP 32 16 see the APD s 99 60 is quite complicated compared to add our sensors from before it has eight channels and one led I could imagine it fits into home automation systems for contactless switches it can sense proximity and gestures can detect the amount of light in a room and even give you information about the color it has an UV and an IR filter and it features an I square C interface a very cool sensor let's check it out first the colors it detects the right colors but if you have a closer look the separation is not as good as with the true color sensors from before especially between green and blue next we try proximity you have to go quite close to get some readings so it is good for a switch behind class for example it also should be able to detect different directions of your hand at a distance of around 15 centimeters or 6 inches first I was very frustrated with the sensor until I discovered that the Sparkfun example works with interrupts and I had to adapt the sketch to the ESP 32 as usual I leave a link in the description to my sketches after I fixed it it works fine all in all a lovely sensor as the English would say the AP 3216 see only has proximity and ambient light it also connects to I square see please do not forget to power the LED using a 220 ohms resistor between the 3.3 volts and the LED pin also here the distance for detection is rather small these were the sensors I found in my boxes I'm sure there are many others available maybe you have a favorite please share it in the comments summarized we tested various sensors which detect light all sensors are specialized on particular wavelength one detected UV light quite a few measured the visible light because the photo transistors or photo diodes used on the chips seem to be quite sensitive also for infrared either the chip has a built-in IR filter or we have to add one otherwise we can't get completely wrong readings because the light levels are very different indoors and outdoors we either have to select sensors which have a high dynamic range or we have to adapt them to the use case with dark glasses for color recognition the TCS 34 725 is probably the best choice for me the looks sensors simulate the light sensitivity of an eye to show us the brightness as we see it for elementary on-off applications light dependent resistors or photo transistors are a cheap and a good choice the apts 99 60 gesture and proximity sensor worked fine and detected gestures as well as sensed RGB light proximity detection also works fine on a short distance the AP 32 16 C is slightly cheaper than the APD s 99 60 so go for it if you do not need RGB or gesture one sensor not covered here was the VL 53 l0x distance sensor it was covered in an earlier video and it is very good in detecting proximity also on longer distances up to 1 meter it uses laser light most sensors had an I squared C interface and I found libraries to use them only the TCS 3200 uses frequency a very special interface and maybe a little outdated as always you find all the relevant links in the description I hope this video was useful or at least interesting for you if true please consider supporting the channel to secure its future existence thank you bye

Channel: Andreas Spiess

Views: 72,100

Rating: 4.9775281 out of 5

Keywords: arduino, arduino project, beginners, diy, do-it-yourself, eevblog, electronics, esp32, esp32 datasheet, esp32 project, esp32 tutorial, esp32 weather station, esp8266, esp8266 datasheet, esp8266 project, greatscott, guide, hack, hobby, how to, iot, lorawan, nodemcu, project, simple, smart home, ttgo, wemos, wifi, Lux sensor, lux meter, light sensor

Id: r6mof_5w0rU

Length: 18min 19sec (1099 seconds)

Published: Sun Apr 12 2020