Wind direction & speed sensor questions

[mfisher]

I'm building my own weather instruments and since I'm an aviator I would like to have wind direction displayed in 10 degree increments (like 000, 090, 150, 340, etc.) rather than the 'standard' 16 points.

Am I correct in assuming that mcsTemp currently reads a voltage (or voltages) from a DS2450 that encodes 8 reed switches and then computes which of the 16 points to display?

Would it be possible for me to provide a 6-bit value encoded by a DS2408 for direction to mcsTemp and have the display scaled, stored and displayed as 10 degree increments (as above)?

Further, could I then use one of the remaining bits (DS2408 is an 8-bit device) for the wind speed sensor?

I am very impressed with the plugin - you've done a great job with it!

[Michael McSharry]

I will work with you, but the DS2408 is a difficult device for me to work with because it is used in a variety of non-typical configurations. This makes it easy for a user to have configuration problems. I know I have done the multi-io which is a 4 in / 4 out, the LCD which is a 5 out and 3 discretes as in/out and I think there was something else as well. I started down the road of using an alphanumeric suffix added to the 16 byte serial number to identify how the part was configured. I think I used just about all the 36 database-friendly characters so we will need to relook at that part of it.

The wind speed cannot be done with a discrete and expect the PC to poll at a sufficiently high rate to count revolutions. You will need a DS2423 for this.

[mfisher]

Thank you very much Michael.

After studying the Maxim app notes more carefully, I now see that I'll need to use a DS2423 for wind speed and rain gauge. When using the counters, does mcsTemp poll the counter for the current value and then reset the count to zero in the device?

I've not used 1-wire devices before, so I'm not all that familiar with the features and protocol yet. I truly appreciate your help!!

As for using the DS2048, I'm planning to use a magnetic rotary encoder chip as the sensing element. This device provides an 8-bit output representing the angle of the magnet over the chip. I felt this would be a clean, non-contact method of sensing and the PCB can be completely sealed.

If you need any help w/ coding or documentation, let me know.

I am curious to know your thoughts on my approach.

[Michael McSharry]

It looks like a good way to go. My problem with doing something like this would be the mechanical aspects to get the vane with a magnet mounted near the chip. If you use all 8 bits of the DS2408 for the wind direction then it makes it easier for me. Another thing you may want to do depending upon where you are located is consideration for deicing and in that case you could use one bit of the device as an output to control a heating coil. Likely, better, however, to use a dedicated DS2405 for longer term reliabilty and maintenance.

From the SW perspective the DS2408 will look like a wind direction device with scaling of 360 degrees / 64 binary = 5.625 degree resolution. This could be rounded to decade units or left with integer resolution. It is your call as to what will work for you.

Wind direction at my location is sufficiently variable that resolution to even 10 degrees does not have much meaning. While the sensor is only providing 1/16 the software could use a moving average and report in 10 degree resolution. My thinking is that you may be designing more resolution than is practical for this type of measurement. I'm in the mountains so my wind pattern is very much affected by them. In your case it may not be the case.

[mfisher]

While 8 bit resolution for a wind direction sensor is definitely overkill, I wanted to try this sensor in a somewhat harsh environment (outdoors) as a test for using it in some machines at my shop. For me, the mechanical aspects of using this sensor are a matter of a little time in SolidWorks, a few hours on the lathe, milling machine and soldering station.

I'm located in a coastal valley in So. Cal. about 20 miles from the ocean so deicing is probably not needed on this version. Also, the winds, uuh breezes, here are not too directionally erradic, but I won't know until trying to measure them...

For the sake of simplicity on your part, let's stick w/ the full 8 bits for direction and I really like the moving average to smooth things out.

[Michael McSharry]

If I remember the moving average is already implemented with mcsTemperature with many sensors using the calibration user input as the smoothing weight. I suspect this is not done with wind angle and will need to be added.

My father was a machinist so he made me a few things when I was young, but those metalwork toys never migrated beyond his place of work and I was never the apprentice to appreciate how to use them.