BOFH: We CAN do that with a Raspberry Pi, but think of the BODIES BOFH "So what we'd like to do is have the lights turn on in the foyer when people come into the office," the Health and Safety rep says. "Yep, put a PIR+Daylight sensor unit in," I say. "One of the sparkies could do that for about a hundred quid - or £150 if he's got a holiday coming up." "Yes, but what we'd like to do is …
...Arduino could do it better. Sounds like they'd only need a handful of input lines, so to be REALLY pedantic, a PIC chip would suffice. No need to throw Linux-running microcomputers at these kinds of problems.
Back to the topic at hand, glad to see the BOFH! I wondered if it would come out Sat instead of Fri given the change up.
Yes, except that the 555 is realy not a good choice for longer duration delays. Too much drift on the R or the C.
I designed some stuff years ago with a similar IC, but it had a built in counter so the timings could be pushed out reliably, but I cant remember the number - it had four digits and one of them may have been a 7.
Saved using a 4000 series counter bolted on.
Yes, except that the 555 is realy not a good choice for longer duration delays. Too much drift on the R or the C.
You could sell it as an auto-adjusting delay (and auto-adjust the billed development and build cost) to the company's beancounters.
Seriously, 15 minutes is no problem with decent quality components and the 7555 (CMOS version)
You don't even need a full Arduino, an ATMEGA324 costing about £3, a crystal and a couple of caps is all you need for an embedded application. Heck, for this an ATTINY85 and its internal oscillator will probably do the trick, for less than £1.50
Of course they could of installed what Douglas Adams termed a "Mode Execution Ready" device, alternatively called "Access Standby" or a "on/off switch"
My good wife was recently telling me that in her office the lights are controlled by a PIR, but only in the main office, not the adjoining conference room. The result is if no-one is in the office, people have to periodically emerge from conferences to reactivate the lights.
Sorry to rain on the technology parade, but PIR's could only have been invented by someone at Sirius cybernetics and will be 1st against the wall when the revolution....
My good wife was recently telling me that in her office the lights are controlled by a PIR, but only in the main office, not the adjoining conference room. The result is if no-one is in the office, people have to periodically emerge from conferences to reactivate the lights.
Sorry to rain on the technology parade, but PIR's could only have been invented by someone at Sirius cybernetics and will be 1st against the wall when the revolution....
Not quite right. They were invented by someone in the tech section, but SOLD to you wife's office as "The Solution" by someone from the Marketing Division of Sirius cybernetics who'll be 1st against the wall when the revolution comes....
They are perfectly acceptable and function when used within their design parameters.
I think I will use the weekend hours to acquire one of those since I have an unappreciative beancounter to deal with next week Tuesday.
I must admit, it is a perfect double use tool, first to liberate the beancounter from their self afflicted disease (of counting beans), and then second, covering up the evidence of said liberation.
I think I will put that beancounter under the slab that is being poured for the generator system that the beancounter fought against. ("It will deplete the executive bonus pool!") Perfect karma.
I'm surprised he didn't take the malware angle…
"Ohh, I'm sorry, it seems someone brought an infected USB stick onto the network and so now our security lights are infected with the Saturday Night Fever virus."
Meanwhile a shell script runs:
#!/bin/sh
while true; do
echo $(( ${RANDOM} % 2 )) > /sys/class/gpio/gpio123/state
sleep ${RANDOM} % 5
done
Another way to handle people like that is to tell them that "Yes, it can be done, but will cost (Your annual salary here) per month to implement. When they ask why, tell them it's the maintenace cost. If they pop to the price, pay a PFY to work a light switch every twelve minutes.
Then comes the request for the smartphone app for remote control and monitoring. You quickly create one using an open source library for encryption and security. A hacker uses a zero-day exploit to change the code and strobes the lobby lights, inducing mass epileptic seizures which are recorded and posted on social media. They go viral and the ensuing media hyperbole forces the government to strike a commission which hires highly paid consultants to, after many years, recommend that implementation of such devices be regulated and overseen by a new branch of bureaucracy which requires a great deal of paperwork for regular provision of compliance and monitoring data. All corporations must hire an "IOT supervisory officer" to oversee compliance. Once you finish your criminal sentence for having perpetrated "LightGate" a condition of your parole is to provide volunteer services for the department developing the specification for the mandated middleware which will automate monitoring, collection, and submission of this data using series of interconnected sensors. You instead fake your death and flee to a third-world country.
Simon obviously has more patience than I do .
if it had been me in his situation the conversation would have ended shortly after
the Health and Safety gremlin uttered the word
"computery"
riiiight
adopt Grytpype-Thynne voice
"neddy, close your eyes and say "ow, my bleeding' head"
thud
roll of carpet, shovel, bags of lime, white van..
Yeah, that would be a horrible design, requiring someone in the room to wave their arms every 12 minutes when the lights go out, even if they're doing calisthenics in the room the entire time.
I have had a PIR-sensored room go dark while I was in it. Apparently the sensor didn't have a line of sight to my furiously keyboarding fingers, and I was sitting very still for 10 minutes.
I love PIR lights - running down the hall and hearing breakers CLUNK is just so much fun if you're first into the office. And then there's playing "stealth mission" and seeing how far into a room you can get before the lights go on.
For me that seems to be scarily far too regularly.
I seem to regularly be dead. Some days the touch pads on door locks don't respond to my prodding fingers, PIR lights don't come on and I can walk right up to automatic doors and they don't open, even if I jump around in front of the PIRs.
Any office, meeting room with them that doesn't have a light switch override is really annoying to try and work in.
We got sensors like that where I work, when in the storage room behind a shelve it will turn off(badly placed sensor), so people always jam the door open with a fire extinguisher so that there is atleast light coming in. We also got a similair sensor in the riveting box that doesnt trigger if you are at the far end so it all goes black...
Wish we just had normal light switches..
To save money on lighting they put a PIR in the toilet zone, outside of the cubicles, with an apparent period of 6 minutes. Go in sit-down, open the paper, read for 4 minutes whilst multitasking - light off - pitch black - where is the toilet roll? where is your pants, where is the pool of water you avoided on entering and where the hell is the door? ooh there was a sudden desire for cheap floor coverings.
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