Door control system/Logbook
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All changes/problems reported with the door entry system.
See also http://github.com/londonhackspace/Doorbot/commits/master
2010-09-29
Operator: Solexious
- Worked out why avrdude stopped working - Mark fixed Doorbot to keep the serial port open!
- Wired the door bell up
2010-09-28
Operator: Artag (write-up by Mark)
- Replaced the chocblock with a lovely 25 pin D-Type connector, with soldered joints and heat-shrink.
- Started testing on the scope, but couldn't find a suitable way of using the trigger feature.
- Suggestions for improvements:
- See whether PWM/AC requires less current to trigger the solenoid
- See whether the 5v supply is having difficulty when the reader is powered
- If so, isolate it and use a hefty capacitor to keep that going (rather than supporting the solenoid)
2010-09-27
Operator: Mark
Problem 1
Identified by Solexious at the weekend
Arduino resets on serial open() from bifferboard- Arduino flashes digital outputs high on reset
- Digital output flashing high triggers door open (this seems to be getting worse over time)
Tried:
- Disabling DTS (didn't work)
- Pull-down resistor (10k to 1k)
- Physical reset button on arduino (it also makes the pins flash)
- 120 ohm resistor between 5V and RSET on arduino - works :D
- The board no longer flashes the outputs on boot, but still does when the reset button is pressed.
Workaround:
- Open serial port on boot
- Hope it doesn't restart
To try:
- Check voltage during boot, so see whether either line is spiking
- Replace diode on solenoid
- Resistors to reduce sensitivity of darlington
- Use a capacitor to smooth over the reset pulse, requiring > 1 second to trigger relay
- Rebuild darlington/relay board
- Use a solid state relay (no darlington required)
Problem 2
- Chocolate block "plug" is loose, sometimes causing loss of power at slightest touch
To try:
- Replace with header/plugs (we'll try a D-type on Tuesday)
Fixed by Artag
Problem 3
- Flashing arduino has stopped working (stk500v1: no response)
To try:
- Another arduinio (Solexious will bring one on Tuesday)
This was because doorbot had the serial port open
Problem 4
- Rootfs went away at 4:04am
- This might have been the sensitive chocblock again, as there were people in the space.
Previous problems
- Progressive failure overnight before Sunday of the Arduino talk - very bad. After investigation it was found that the original alarm charger was outputting 6v, so the Nneil donated a wall charger to replace it.
- Numerous bifferboards were destroyed by cigarette lighter regulators which spontaneously become 0 ohm resistors when a large (> 0.6A) current is pulled through them.
- The original spec for a 7805 did not take into account the amount of current passed. 7V * 0.8A = a small radiator.
- The original transistors we tried were not enough to trigger the relay, so were replaced with Darlingtons.