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Author Topic: 1-wire DS28EA00 reading humidity/moisture sensor  (Read 1072 times)
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I have built a grain bin temperature monitoring system for on my farm that uses Arduinos to read DS18B20 sensors and report the readings to my linux server via ethernet/wifi. Now I have a commercially available sensor rope that can also read the moisture level of the grain. It is using DS28EA00 1-wire sensors which report temperature identical to the DS18B20 sensors but they also have 2 GPIO pins that I believe are connected to a humidity sensor. I am hoping someone will be able to help steer me in the right direction to figure out what kind of humidity sensor it is and how to read it via the 1-wire bus. Looking at the DS28EA00's datasheet, it looks like with the right command the DS28EA00 will continuously output it's GPIO states via a data byte (only two bits are actually used) until a reset pulse is generated by the master. I'm wondering if they are using a humidity sensor that continually outputs a frequency in proportion to the humidity. Then I would have to somehow read the "GPIO Status Byte" and convert that to a frequency via software. Any thoughts?
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Do you have a link to more details on the sensor rope?
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Information is limited. It is somewhat a fluke that I even ended up using the same sensors as they do for the temperature only sensor ropes. I expect they don't want people to know their secrets. Here are two pics. It sas 6 of those "lumps" where the sensors are, each about 4' apart. The numbers on the label are:
06MD-I022-S1AB
#4229-V1.1-12C
A#1-MC13678


* moisture end.png (542.53 KB, 1464x136 - viewed 41 times.)

* moisture numbers.png (1115.04 KB, 1224x547 - viewed 45 times.)
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do you have a link to the datasheet?

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I doubt there is a publicly available data sheet. I think it would require some social engineering of the right people (maybe some social lubricant) to get any details on the sensors used, hence the reverse engineering required.
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I doubt there is a publicly available data sheet. I think it would require some social engineering of the right people (maybe some social lubricant) to get any details on the sensors used, hence the reverse engineering required.
I don't doubt, it is here - http://datasheets.maximintegrated.com/en/ds/DS28EA00.pdf -

it is a "1-Wire Digital Thermometer with Sequence Detect and PIO"

As it is from the same manufacturer as the DS18B20 and the register layout looks familiar (not checked the details)
I would start with DS18B20 code to see how far it works.
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As I mentioned in my first post, I am already reading the temperature from the DS28EA00 using the same method as for the DS18B20. I'm looking for suggestions about what kind of humidity sensor could be used behind the DS28EA00's GPIO pins. The data sheet I'm talking about that is not publicly available is for this assembled sensor rope. I may be able to disassemble it without damaging it. Hopefully I can see the ICs then.
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Sorry, misunderstood your question, my mistake  smiley-red smiley-red smiley-red  smiley
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Not sure if you're still working on this.
Thought that cable looked familiar.   Here is the patent on how they are doing it.   US20130092432 A1
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Looks about right. Here's a thread on the combine forum relating to guys building systems.

http://www.thecombineforum.com/forums/31-technology/134681-grain-monitoring-systems.html
« Last Edit: February 19, 2014, 10:48:25 pm by Matt Elias » Logged

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Can't believe patents are granted on something like this.  Take two off-the-shelf sensors, hook them together a minimal of circuitry and patent "in a bin."  Add "in a phone" and you can have a new patent to make money with.  Astounding.  Yay for fostering innovation.

The combine forum thread mentioned SHT15s as well, so that's probably what you have.
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Can't believe patents are granted on something like this.  Take two off-the-shelf sensors, hook them together a minimal of circuitry and patent "in a bin."  Add "in a phone" and you can have a new patent to make money with.  Astounding.  Yay for fostering innovation.

The combine forum thread mentioned SHT15s as well, so that's probably what you have.

no big deal.  you can take two off the shelf, add in an LED to make your special version and get that patented.

add in wifi and you get a second patent.

BTW, you have to patent in every country at once.  the day you countries patent is released, there is someone who reads it, copies it, puts their name on the paper and files for all international patents.  just a clerk who has no idea of technology.  the world wide patent is now 'first to file' and has no requirement to understand or even develop a thing.
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