February 1, 2010
about 2 months ago
A heads up for people planning to use this for permanent outdoor mounting: The epoxy coating is not UV protected. After 6 months outside in Hawaii, mine has become completely opaque. It’s still functioning, but I have no idea how much power I’m losing.
about 3 months ago
I did cover the board, except for the sensor package, with hot glue to protect the pads. It’s possible that wasn’t enough. For my next one, I think I’ll pot the entire board in epoxy (after mounting a filter cap.)
I second this. Mine just died after being outside (in an enclosure but still exposed to mist and moisture) in Hawaii for 6 months. I haven’t found a place that carries these filter caps either.
about 5 months ago
After a few months in the very humid Hawaii climate, my sensor now basically says 119% humidity all the time. I wonder if this is a condensation issue.
Tutorial - Wireless XBee/AVR Bootloading
about 7 months ago
I’ve now also added a pretty detailed how-to about how to do wireless bootloading with series 2 XBees and avrdude. It’s at my blog.
about 9 months ago
I double checked by looking at the read-out values of the channels instead of just the lux values. With 100ms integration, 1x gain, the channels increase in value until they peg at 37177. ch0 will saturate first, since it has the highest count rate, at about 40,000 lux. From that point, any increase in light level actually brings the calculated lux down, because the only channel that keeps going up is ch1. When they both saturate at 37177, the calculated lux value is about 805.
Actually, does anyone know if setting a new integration time interrupts the ongoing integration? If not, it’s hard to know when to read out the data. Supposed it’s set to an unknown integration time and I want to use 14ms. If I then have to account for the possibility that it could be running a 400ms integration first, I could have to wait up to 414ms before the correct result shows up. The datasheet doesn’t seem to specify this, it just says “when the device is powered up, it will start doing continuous 400ms integrations.”
I think the library is correct except that it looks for 0xffff readouts as evidence of channel saturation. I’ll submit a bug fix. But I can’t get any measurements above ~40k lux, and in direct sunlight the sensors saturate.
about 9 months ago
Oh sweet. I don’t suppose I can “upgrade” mine? ;-)
Just so everyone is aware, this device can not handle full daylight without saturating, and the shorter integration times don’t help because the limiting factor is the maximum count rate (see Note 6 on p5 of the datasheet), not the maximum value of the readout register. The Sparkfun library doesn’t account for this lower saturation level and it will end up looking like the lux value actually goes down in bright sunlight.
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