Last night (March 2, 2010), I ran a test with the door minder circuit. The separation between the encoder and decoder was 365cm (approx 11.98ft), and the encoder was being toggled at 20Hz. This means the expected signal from the decoder should be around 10Hz because the decoder changes every time the encoder sees a high signal. A signal was produced, but it was not nearly a consistent 10Hz. Unfortunately, in trying to adjust the LED, I broke one of the wires off, and, of course, lost the signal. Eyeballing it, I would say the decoder picked up 3 or 4 in every 20 toggles from the encoder.
Previously, the experiment was ran with both chips on the same board with both the LED and transceiverpointing towards a mirror. A signal was produced, but last night, I realized this was a reflection of of my shirt/hand. I believe the LED is not focused enough. The current through the LED in both cases was around 45mA (I didn’t have a chance to test it with anything lower before I broke the LED). I am, of course open to any ideas on how to proceed.
Program:
(1)Clock (prog Clock 1 Run#)
(2)Base Station (tiny-os → make telosb install.0)
(3)Pagers (prog Pager ID#)
1.Check batteries are present + have enough charge
2.Label and program correct number of pagers
3.Check that labels match computer program + programmed as pagers
(4)Anchors (prog Anchor ID#)
1.Check batteries are present + have enough charge
2.Label and program correct number of anchors
3.Check that labels match + programmed as anchors
(5)Hand Cleaners (prog HandCleaner ID#)
1.Check batteries are present + have enough charge
2.Calibrate them in wall bracket
3.Label and program correct number of hand cleaners
4.Check that labels match + programmed as hand cleaners
Practice In Lab
(1)Make sure Base Station picks up signals from all pieces
(2)Make sure everything syncs + shows up on the demo run as its supposed to
(3)Get all supplies in tool box
(4)Pack up all programmed motes
Set-Up In Hospital
(1)Unpack all parts
(2)Check that everything is still in working condition
1.Batteries still working
2.Hand cleaners properly calibrated
3.runsfb again and see that everything shows up
(3)Put all parts in their specific locations
Mike’s comment on my previous post:
It may be useful, instead of oscillating the input to the encoder, to have the mote toggle the input to the encoder. This should cause a code to be sent once and received, which will then cause the corresponding pin on the decoder to toggle. The mote can then verify this toggle to indicate that the beam is uninterrupted. The mote can run this routine every 5ms or so. Two or three failed transmissions in a row could be considered as an activation, and the mote could then broadcast it’s “my beams been broken” signal.
This seems like a good idea, but we must also account for a 27ms delay between when a pin on the encoder is toggled, and the corresponding changed is noticed on the decoder. Here is a screen from the oscilloscope:
The output from the pin on the decoder is on top, and the toggle for the encoder is on bottom. An oscillating toggle was used so we could view this delay on the scope. Notice the 27ms gap, shown by the cursors, between when the encoder is toggled again from being off, and the change in the decoder pin.
To be clear, a “broken signal” in Mike’s comment means there is no change in the output of the pin on the decoder. Notice on the scope, it only changes when the LED is on, goes off again, and then comes back on. If the second on, in this example is interrupted, and the LED goes off before the signal reaches the transceiver, the decoder pin will not change.
Here is a picture of the current circuit, as it is wired. For testing, I plan to put both on the same board.
