July 29, 2013
about 3 months ago
I was skeptical about purchasing one of these sensors since I saw that so many people are having issues with it. That said, I thought I would clear up some of the things that I confronted when working with this sensor today.
I connected the sensor in the following manner:
- White to TX of Serial3 on an Arduino Mega
- Green to RX of Serial3
- Red to +5VDC
- Black to GND
The sample Arduino Mega code from the manufacturer has a bug where the baud rate for Serial3, the serial port that the sensor is to be communicating on, is set to 9600 instead of 38400–the default baud rate for the sensor
The sample Processing code has the baud rate set to 38400 when the Arduino Mega baud rate for Serial0, the serial port for the Arduino Mega to communicate with the computer, is set to 9600, so I changed the baud rate to 9600 in the Processing code.
The sample Processing sketch has a bug where it apparently attempts to automatically select which COM port the sensor is connected to, but as my install of the Processing IDE was fresh, I apparently didn’t have whatever library that may be needed in order to make that function automatic. To fix this, I changed this:
myPort = new Serial(this, Serial.list(), 38400);
myPort = new Serial(this, "COMx", 9600);
Where “x” is the number of the COM port that my Arduino Mega is connected to. Yes, you need the double quotes.
There was some question about angle of view and distance from subject, which I explored for a bit. I found that the sensor has a fairly narrow angle of view, approximately 10-degrees. The working distance is from about 25mm down to about 1mm if illumination is good. I found that as the sensor gets farther from the subject, the color seems to be more influenced by the surrounding colors, but the color in the center of the target is most pronounced.
Finally, a question that I had was whether or not this device viewed color from the perspective of a spectrometer, or from the perspective of the human eye. The difference is that when one is looking at different colors of light that mix, the eye will see the resulting color from the mixture of the light where a spectrometer will be able to discriminate the light into the separate wavelengths unless some sort of nonlinear crystal is used to mix the two. I was glad to find that this sensor views the color of light from the perspective of the eye, which opens up a great number of potential applications for this.
News - Enginursday: Favorite Too…
about 3 months ago
It’s not often that I strip wire, but when I do, I use a laser.
about 3 months ago
Yes, the only thing solar eclipse glasses are good for are solar eclipse. Certified glasses are available from a company called Kentek. Here’s a link to a wide selection: http://www.kenteklaserstore.com/laser-eyewear-search-tool.aspx#q%3DY2IzNzRiZDMtZmY1MC00M2JlLWIzNWItNjRmNzE4YmY4ODQy_ZWJlMzA0NDItODkyNS00Yjg3LTg2ZmUtMzc5N2M5ZmRhYjgy%26o%3D-1%26p%3D1%26i%3D15%26h%3D996%26l%3D29%26prot%3D0%26protMode%3D
This is a CW laser.
If you add dry ice to water then you can shoot the beam through it and view the beam indoors.
You may want to consider adding a heat sink or even an active cooling Peltier module.
“like most green lasers” should be “like most green laser pointers and other CW lasers” since a couple of different crystals can be used to convert to green laser from 1064nm, such as LBO and BBO, with LBO being the most common for high-powered pulsed green lasers. The conversion efficiency of KTP is very low in a pulsed laser so it is less desirable in industrial and scientific applications, but KTP operates more efficiently than the alternatives when a CW [continuous wave] source is present, such as the case with most laser pointers.
about a year ago
Comparing the two datasheets, it seems that they may work together. The RFM22B will need to be in FSK modulation mode. Both will need to be on the same carrier frequency, have the same frequency deviation, and same bit rate. I have purchased both modules and I hope to test this out this weekend.
Honestly though, the RFM22B is so much more flexible and totally worth the extra few dollars, in my opinion; it will save you a headache to just get the RFM22B.
Yes! OOK [On-Off Keying], which is one of the three modulation modes this module uses, is a type of amplitude-shift keying modulation which does exactly what you want it to do.
No public wish lists :(
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