View Full Version : Infrared Thermometer Drivers (ZyTemp and All Sun) for Harbor Freight IR thermom

05-18-2010, 02:43 PM

I saw Harbor Freight had a few IR thermometers on sale when I was there a few days ago, so I picked them up, figuring they'd come in handy for something. But, like everything that comes into my hands, it gets disassembled at least once ;) . To my surprise, they all were quite hacker friendly! Opening the two smaller ones (Cen-Tech 93983 and 93984), I found 0.1" connectors exposed, and a brand name (ZyTemp). I looked them up and found a protocol and message format (for their embedded modules, which is also valid for these). From the pictures, the thermometers look to be rebranded ZyTemp TN105i2 and TN203 devices (D:S 1:1 and 6:1).

The larger one had what looked like 5V TTL level RS232 on a 2mm header just above the battery (with a sticker over it). I soldered a 0.1" header to that, connected it, and found data being sent periodically. Unfortunately, I wasn't able to find any protocol information, so I had to reverse engineer this message, and only went through the hassle of figuring out a few fields like message start, object temperature, and checksum. I've since determined this to be a rebranded All Sun EM520B (D:S 8:1).

Anyway, I wrote a few simple demos for the prop to use these. They output the temperatures read from the thermometer to the serial port. I attached those, as well as a few pics of the thermometers. Of course Parallax also sells the Melexis modules, which are probably better for embedded stuff (I think a little bit smaller), but these are cool and cheap.

Also, the ZyTemp devices communicate with an SPI-like protocol, but requires the Prop to be the slave. I couldn't find a Prop SPI slave driver, so I modified Beau Schwabe's SPI Spin (master) driver to support it. This may be of use to others, though it certainly hasn't been thoroughly tested. It's in the attached ZyTemp archive.


Post Edited (DogP) : 5/18/2010 7:50:39 AM GMT

05-18-2010, 02:46 PM
Hmm... I guess I can't attach the zipped code archive, so here are the individual spin files. I also added a pic of one of the thermometers connected to the Prop.


Post Edited (DogP) : 5/18/2010 8:28:16 AM GMT

05-18-2010, 07:00 PM
Very cool DogP (gotta love that name!)

So do I understand correctly that both units (HF 93983 and 93984) work as described?

I noticed that 93983 is on sale for $9.99 here: www.harborfreight.com/non-contact-pocket-thermometer-93983.html (http://www.harborfreight.com/non-contact-pocket-thermometer-93983.html)

05-18-2010, 08:23 PM
Yep... both work exactly the same, though I like the 93984, since it has a laser to see what you're pointing at, and it has a smaller spot (the 93983 measures a 1" spot at 1" distance, the 93984 measures a 1" spot at 6" distance).

The large one (96451) works as well (All Sun driver), and I think it's nicer as a general thermometer (nice display, laser, and measures a 1" spot at 8" distance), though it seems to take readings in bursts (usually 3 really quickly, then pause for ~1 sec), which is slightly odd if you're wanting to use it for something automated. I also don't like the fact that there's no documentation on using it like I want to.

Also, if you're buying anything from Harbor Freight, be sure to look around for coupons/ads... lots of times they're on sale even cheaper than advertised on the site, and you can usually find a 20% off a single item coupon.


WBA Consulting
05-18-2010, 10:33 PM
Very nice, I love to see easily obtained items hacked for use with the propeller. I will definitely have one of these on my next Harbor Freight shopping list.

Andrew Williams
WBA Consulting
WBA-TH1M Sensirion SHT11 Module (http://www.aestheticacoustics.com/sht11_01.htm)
My Prop projects: Reverse Geo-Cache Box (http://forums.parallax.com/showthread.php?p=869153), Custom Metronome (http://forums.parallax.com/showthread.php?p=906277), Micro Plunge Logger (http://forums.parallax.com/showthread.php?p=875698)

05-19-2010, 11:50 AM
Yeah... there's something cool about using stuff in ways we're not supposed to, and I appreciate them leaving pins accessible so we can do it easily ;) .

Another easily hackable thing from HF is the digital caliper. I have one, but haven't connected to it yet since I don't have a need for it, but these: www.harborfreight.com/6-inch-digital-caliper-47257.html (http://www.harborfreight.com/6-inch-digital-caliper-47257.html) can be hacked like described here: www.compendiumarcana.com/caliper/ (http://www.compendiumarcana.com/caliper/). I think the most difficult part is converting the 1.5V logic level, but that's not really a big deal. It seems like people use this for getting a digital readout for DIY CNC mills, and I'm sure there's plenty of other good uses.

BTW, the thermometer objects have been posted to the obex here:

ZyTemp: obex.parallax.com/objects/606/ (http://obex.parallax.com/objects/606/)
All-Sun: obex.parallax.com/objects/607/ (http://obex.parallax.com/objects/607/)


cichlid fans
06-17-2013, 03:24 AM
very good jobs, i am seaking this applicaton for a long time.

recently, i found the new Harbor freight gun shape infrared thermometer(#69465) also have the similar SPI interface as described, will try to see if it is made by the same manufacturer.

tks anyway.

06-17-2013, 07:22 PM
How about mounting it on a couple of servos and 'scanning' a thermal image (albeit slowly)?