DogP
05-18-2010, 02:43 PM
Hey,
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.
Pat
Post Edited (DogP) : 5/18/2010 7:50:39 AM GMT
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.
Pat
Post Edited (DogP) : 5/18/2010 7:50:39 AM GMT