Friday, May 23, 2008

Eye-Fi Power Consumption

I got a very small, 6 inch USB extension cable from my favorite cable store. Then, I chopped it up to get access to the power supply wire and clamp my cheapo ammeter on to it. I plugged a card reader into my PC with this contraption. Note that I'm measuring the USB power supply at ~5v, not the 3.3v that the card actually gets and that these are very unscientific measurements made with Radio Shack equipment.

My card reader alone: ~31 mA (unchanged if a normal SD card is simply plugged in)
After plugging Eye-Fi card in (no pending uploads): 56 mA (25 mA for the card)

All the numbers that I'll state from here on include only the amount that the Eye-Fi card is using after subtracting the amount for the reader.

Then, I took a picture to make the start start an upload and turn on its radio. The ammeter was bouncing all over the place, but it peaked at over 170 mA and I'd guess that the card averaged about 120 mA during the upload. The strange part is that, after the upload, the power usage only goes back to 40 mA. It never (at least in a couple of minutes) gets back to the 25 mA where it started. I wonder if the radio never gets completely turned off. Hmm.

My Nikon D50 has a 7.4v 1500 mAh battery. Let's be stupid and pessimistic and assume that the card is running at its very peak power of ~170 mA and round that 5v USB voltage up to 7.4v. That's still almost 9 hours of theoretical power. I can't possibly be seeing that effect on my battery life, right?

Is my methodology screwy? Any electrical engineers out there that want to tell me how much of an idiot I am? Email me.

Tuesday, May 20, 2008

New Eye-Fi Products

I was offline last week, attending a few family members' college graduations. While I was gone, Eye-Fi announced a few new products. Just wild conjecture, but I bet that the only difference in the cards is the firmware. I doubt we are seeing a hardware rev at all. In any case, looks like Eye-Fi has some good marketing folks! I love to see companies that put out solid incremental products like this.

The Eye-Fi Explore can also now log on to certain WiFi hotspots but apparently no T-Mobile or AT&T ones like at Starbucks. This is great progress and I hope to see these capabilities widening in the future, but this is definitely a baby step. More wild conjecture, but I bet that Wayport either already has or was able to implement a simplified log-on which the Eye-Fi card could perform. Remember, the card has very little RAM and a pretty tiny program storage area. It has no real web browser and can't do the SSL that most web sites use to secure authentication information.

The "Explore" can also evidently geotag your photos if the WiFi access point you are using has been mapped. According to this page, the tagging is done in the "Eye-Fi Service", which I assume means it happens after the upload from the card. I bet there's an extra bit of data sent along with the access point's MAC address during the upload now. I'd love to get some dumps of these uploads happening if anyone has one!