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MLX90614 Modification - Weatherproofing! — Parallax Forums

MLX90614 Modification - Weatherproofing!

everesteverest Posts: 141
edited 2010-06-09 16:40 in Accessories
I'm trying desperately to create a weatherproofed IR module and it's really causing me some difficulty. A truly IR transmissive optical sheet is hundreds of dollars for a tiny piece.

I've gotten my hands on a few MLX90614 thermometers (the actual piece from Melexis) and it turns out they are completely sealed and weatherproof, and have been mounted outdoors by some users. The problem is that they are insanely hard to operate with a Stamp2 or other microcontroller (as far as I can tell). I also have several of the Parallax sensor that incorporates the MLX90614 series and obviously. . .those work perfectly!

Question: It it possible to weatherproof one of the parallax sensors? I have both a 90 and 10 degree unit and even if I seal the lens on the 90, it would fill up with water in the rain. The 10 degree unit has the MLX90614 sensor mounted in such a way that it's physically impossible to protrude the sensor through an enclosure. I tried to remove the MLC90614 from one unit, but it was darn near impossible and I broke one that way.

Any help/recommendations would be much appreciated. Thanks!

-Jeff

Comments

  • TimmooreTimmoore Posts: 1,031
    edited 2010-06-08 06:31
    If you want to use a propeller I have code that drives the MLX90614·directly. See the attachment.
    zip
    zip
    MLX90614_test - Archive [Date 2010.06.07 Time 23.32].zip
    37K
  • everesteverest Posts: 141
    edited 2010-06-08 06:36
    That might help. . .thanks! I don't suppose you have a schematic that goes along with that do you? I'd be curious to see how you wired up that little sensor. I've been looking mainly at the PWM output up to now, this is the first SMBus approach I've seen.

    -Jeff
  • TimmooreTimmoore Posts: 1,031
    edited 2010-06-08 06:42
    Pin 1 SCL -> Prop Pin (28 works), needs 4.7K pullup to 3.3V
    Pin 2 SDA -> Prop Pin (29 works), needs 4.7K pullup to 3.3V
    Pin 3 Vdd -> Prop Pin MLXPowerPin (16) - used to power the sensor, means the prop can power it down when there is a problem
    Pin 4 Vss -> Gnd
  • Temp-sensTemp-sens Posts: 2
    edited 2010-06-09 06:43
    Be aware that the MLX90614 from Melexis as standard comes with the SMBus interface enabled, NOT the PWM enabled (that has to be done using the SMBus).
    So if up to now you tried communicating using PWM, it's normal that the MLX90614 did not respond.
  • everesteverest Posts: 141
    edited 2010-06-09 16:40
    Yea, I figured that out. . .I actually tried a bunch of circuits with my Stamp2e and then tried my Zbasic chip and tried to use their I2C built in functions. . .I pushed a pulse that should force it into SMBus mode even if the EEPROM is set to do PWM. Then I threw EVERY possible byte at my MLX90615 (very similar to an MLX90614 just 3v, smaller, and slightly re-arrange pins) with resets between each byte. I can't get that little sucker to send me an ACK no matter what I sling at it.

    I hacked it out of a $9 IR thermometer I got at Harbor Freight so my suspicion now is that it's not a normal MLX90615, maybe it's a specialized version that only does PWM. . .??? I just don't know how I would even tell quite honestly. I guess I need to bite the bullet and buy an oscilloscope!

    -J
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