Computing stuff tied to the physical world

JeeLink flash memory

In Hardware, Software on Nov 29, 2009 at 00:01

The recently updated version of RF12demo automatically logs all incoming data to the 1 Mbyte flash memory in a JeeLink. It looks like this is starting to work fairly well – I’ve been leaving a JeeLink on for over a week now, picking up packets from a number of different sources around here. It’s still only 80% full:

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So the JeeLink is now at page 3102 of 3840. Here are the first and last lines from the dump command:

Screen shot 2009-11-28 at 12.36.37.png

Screen shot 2009-11-28 at 12.38.30.png

The first two numbers after the colon are the reboot count and the time in seconds since reboot. There have been a bunch of reboots (most of them caused by me connecting to the JeeLink via a terminal program to see how it’s doing). The last run has been going for almost 24 hours.

Here are the first and last lines of the actual stored data replay:

Screen shot 2009-11-28 at 12.42.30.png

Screen shot 2009-11-28 at 12.45.23.png

Again, the first two numbers on each replayed packet are reset count and seconds since reboot. The rest is the packet data itself.

That’s quite a bit of stored data – almost 84,000 lines of text. It took over 7 minutes to get it all across USB at 57600 baud. Each received packet of data uses about 10 bytes of flash memory on average, in this example.

These results are better than I expected. Even with much more data coming in, it should be possible to leave the PC turned off over say the weekend, with the JeeLink collecting all incoming data and then replaying it when the PC comes back on. The only requirement is a powered USB socket.

Good. My home monitoring network won’t need a PC or server to be constantly on, since I don’t intend to set up around-the-clock internet access to this info – unless perhaps while away from home.