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by Tarcas
Sat Sep 27, 2014 7:36 pm
Forum: Automation, sensing and robotics
Topic: Trigger Video Loop
Replies: 3
Views: 1864

Re: Trigger Video Loop

If you can do something from the command line, you can do it from a shell script. If you can do it from a shell script, you can do it based on a GPIO input, such as a button or motion sensor. All you do is start the script, and within the script, have it look at the GPIO pin, if it's not activated t...
by Tarcas
Fri Sep 26, 2014 5:38 pm
Forum: Automation, sensing and robotics
Topic: FIRST Robotics
Replies: 25
Views: 10636

Re: FIRST Robotics

I'm not an expert on this so don't quote me on this but if you do not use the USB or Ethernet then you can simply supply the raspberry pi with that limited voltage. 8 ma is out of the question. :) Edit: researched and found that it is about 400 ma. I will try to test it on mine. I haven't done it, ...
by Tarcas
Thu Sep 25, 2014 11:32 pm
Forum: Raspberry Pi OS
Topic: bash bug / shell shock now fixed on Raspbian
Replies: 55
Views: 23950

Re: bash bug / shell shock now fixed on Raspbian

Seeing as this is the first search link that comes up for 'raspberry pi shellshock' for me I think its worth mentioning that to update the pi users can open a terminal and type sudo apt-get update and this should install all the packages to fix this bug. (Correct me if I'm wrong about that, only ne...
by Tarcas
Thu Sep 25, 2014 10:50 pm
Forum: Automation, sensing and robotics
Topic: Logistics of attaching components to robots
Replies: 6
Views: 1326

Re: Logistics of attaching components to robots

For wiring, if you use ribbon cable, you can tear off the number of wires you need and keep them attached to each other. That's what I've done with my home automation system. I got a few ribbons of 1 pin to 1 pin wires (some male, some female so I have what I need.) and after I moved my GPIO pin ass...
by Tarcas
Thu Sep 25, 2014 10:39 pm
Forum: Advanced users
Topic: [Hardware] Can a model A RasPi survive this ?
Replies: 9
Views: 2360

Re: [Hardware] Can a model A RasPi survive this ?

Is there a reason you are using a Pi instead of something like an Arduino mini, micro, or nano? All are quite tiny compared to the Pi. There are a lot of things that the Pi can do that the Arduino can't (at least without add-ons) but you've already chopped a good number of them off. Just a suggestio...
by Tarcas
Thu Sep 25, 2014 10:33 pm
Forum: Advanced users
Topic: PoE Ethernet
Replies: 10
Views: 8034

Re: PoE Ethernet

I don't recommend having more than 5 volts wired to a USB socket. Sooner or later something sensitive is going to be plugged in and not survive. Right. I'd use a higher voltage over the Ethernet cable (7v minimum as stated previously, but the higher the better. PoE uses 44v for a reason, but you do...
by Tarcas
Thu Sep 25, 2014 1:35 pm
Forum: Advanced users
Topic: When will bash for Raspbian be patched for CVE-2014-6271?
Replies: 7
Views: 2269

Re: When will bash for Raspbian be patched for CVE-2014-6271

From the register article: You can check if you're vulnerable by running the following lines in your default shell, which on many systems will be Bash. If you see the words "busted", then you're at risk. If not, then either your Bash is fixed or your shell is using another interpreter. env X="() { :...
by Tarcas
Mon Sep 22, 2014 2:00 pm
Forum: Automation, sensing and robotics
Topic: Setting Up home automation.
Replies: 9
Views: 3350

Re: Setting Up home automation.

I've done something similar, but with more sensors and fewer relays. I wrote most of my own code, which it doesn't sound like you're looking to do, but I have some suggestions for your setup... Take a look at webiopi. It might not be quite what you're looking for, but it should give you some ideas. ...
by Tarcas
Tue Sep 16, 2014 8:16 pm
Forum: Automation, sensing and robotics
Topic: Robustness Test for Raspberry Pi
Replies: 2
Views: 1088

Re: Robustness Test for Raspberry Pi

Take a look at MRTG to record and graph data. It uses SNMP to gather data and a database to store it, and I know I saw a tutorial somewhere to use it with a DHT22 or 11 temperature and humidity sensor. I'm curious to know how you'll test "robustness" with a single device. Unless I'm confused as to w...
by Tarcas
Thu Aug 28, 2014 6:01 pm
Forum: Automation, sensing and robotics
Topic: Switch Circuit
Replies: 8
Views: 1809

Re: Switch Circuit

Are you talking about making the Pi into a sort of advanced FPGA (Field Programmable Gate Array)? What are you actually trying to accomplish? It sounds like what you're asking is "instead of doing something in hardware, can I just do it in software on the Pi?" Which, of course, can be answered only ...
by Tarcas
Thu Aug 28, 2014 5:56 pm
Forum: Automation, sensing and robotics
Topic: home automation
Replies: 3
Views: 2207

Re: home automation

As far as which Pi to use for home automation, I am using the B+ and highly recommend it. The expanded GPIO is the killer app, but additional USB ports and reduced power consumption can both help too. If you're running it headless like I am, the change to the RCA video plug makes no difference. How ...
by Tarcas
Thu Aug 28, 2014 2:22 pm
Forum: Automation, sensing and robotics
Topic: GPIO Controlled gun/projectile
Replies: 1
Views: 771

Re: GPIO Controlled gun/projectile

You mean something like this? it's USB so you wouldn't need GPIO, but you could always open it up and hack it. (Since it runs of 5v and your GPIO is 3.3, you may need transistors to drive the servos and whatever else you find inside. Or you may happen to find that it works fine on 3.3v as well.)
by Tarcas
Mon Aug 25, 2014 7:34 pm
Forum: Automation, sensing and robotics
Topic: Multiple blind motors and switches for home theatre
Replies: 2
Views: 1586

Re: Multiple blind motors and switches for home theatre

I commend your ingenuity. This sounds like a great project. As for whether the 12V signal line needs to be stepped down to 3.3v, the answer is yes. A voltage divider comprised of two resistors will be an extremely cheap and easy way to do this. Google "voltage divider" to find the equations to deter...
by Tarcas
Mon Aug 25, 2014 3:12 pm
Forum: Automation, sensing and robotics
Topic: MOSFETS for ir led
Replies: 2
Views: 1129

Re: MOSFETS for ir led

He's using 3 IR LEDs as headlights. I don't know the specs on his IR LEDs, but the ones in my reflective sensors take 60 mA each at 5v, neither of which can be supplied by the GPIO. While they work at 3.3v and/or lower amperage, they're not as bright. I'm sure he decided to use the MOSFET as a switc...
by Tarcas
Mon Aug 25, 2014 2:48 pm
Forum: Automation, sensing and robotics
Topic: Turning off sensors between readings -- wise, or not?
Replies: 3
Views: 910

Turning off sensors between readings -- wise, or not?

I'm working on a home automation project, piece by piece. I've got a relay for a garage door opener, and some reflectivity sensors to determine the position of the garage door (up, down, or neither) and some hall effect sensors for swinging doors. I will soon be adding some DHT11 and DHT22 temperatu...
by Tarcas
Thu Aug 21, 2014 5:15 am
Forum: Automation, sensing and robotics
Topic: Resistor ladder for switch
Replies: 2
Views: 994

Re: Resistor ladder for switch

You also have the option of expanding the GPIO with a GPIO chip and thereby having more pins to play with, only taking up the SPI (or whichever) bus pins on the Pi. Depending on your reason for minimizing pins, it might or might not be your best option.
by Tarcas
Thu Aug 21, 2014 4:56 am
Forum: Automation, sensing and robotics
Topic: Starter electronics kit
Replies: 4
Views: 1425

Re: Starter electronics kit

great stuff. thanks. FYI, the ADC that he mentioned can be gotten quite inexpensively on Ebay. I got one for I think between $3 and $4 several months ago (I haven't actually tested it yet, sorry.) http://www.ebay.com/itm/1pcs-PCF8591-AD-DA-AD-DA-Converter-Module-Light-Temperature-Sensor-Waveform-/1...
by Tarcas
Fri Aug 15, 2014 6:48 pm
Forum: Automation, sensing and robotics
Topic: Where do you start to create logic like a Roomba
Replies: 8
Views: 2659

Re: Where do you start to create logic like a Roomba

If you're wondering about the sensors, read up on robotics. Bump sensors, drop-off sensors (reflective sensors), range finders, and so on are pretty common. To detect whether it's hitting a lot of dirt, I believe it uses a piezoelectric sensor. The wheels have encoders so that it can determine how f...
by Tarcas
Thu Aug 14, 2014 11:48 pm
Forum: Automation, sensing and robotics
Topic: Occupancy sensing
Replies: 6
Views: 5941

Re: Occupancy sensing

For house occupancy, I'm going to be using my wife's and my cell phones. I've set static IPs for each device on my house wifi, and if I can ping one, that means that person is home. If not, it's fairly safe to assume they're away. I suppose I'll find any glitches when I start using it. For room occu...
by Tarcas
Mon Aug 04, 2014 9:47 pm
Forum: Automation, sensing and robotics
Topic: Reviving an water damaged robot mower
Replies: 3
Views: 933

Re: Reviving an water damaged robot mower

Use a multimeter for the battery, to determine whether it holds charge and at what voltage. If you turn a stepper motor by hand, it turns into a low-voltage AC generator. You can use this fact to test it and determine the pinout of the wiring if you need to. Plug an LED across 2 leads. If it flicker...
by Tarcas
Mon Aug 04, 2014 9:44 pm
Forum: Automation, sensing and robotics
Topic: Reed switches
Replies: 8
Views: 2567

Re: Reed switches

These would be for doors and windows and I don't foresee having wires outside the house so it sounds like normally open should do the trick. And I appreciate the info on connections to GPIOs as well, thanks to everyone who replied. Just because the wires aren't outside doesn't mean they can't be co...
by Tarcas
Mon Aug 04, 2014 9:30 pm
Forum: Automation, sensing and robotics
Topic: Open a garage door?
Replies: 5
Views: 1546

Re: Open a garage door?

I've got a spare garage remote wired into a relay. This keeps the two circuits (which run at different voltages) completely separate, unlike a transistor. The latter may be sufficient, but just to be sure, I used a relay. I would assume that X10 devices could be used similarly. I just opened the rem...
by Tarcas
Sat Aug 02, 2014 10:43 pm
Forum: Raspberry Pi OS
Topic: How to reduce headless boot time without disabling Ethernet?
Replies: 5
Views: 1684

Re: How to reduce headless boot time without disabling Ether

I always leave my systems plugged into the network, so forgive me if this isn't a valid option but... Would it be possible to disable Ethernet at boot and then enable it after boot, so that your critical tasks start sooner, but then Ethernet is available when (if?) you need it? Doesn't work if you'r...
by Tarcas
Fri Jul 18, 2014 8:48 pm
Forum: Automation, sensing and robotics
Topic: an automatic mailbox
Replies: 4
Views: 1269

Re: an automatic mailbox

Start with a more thorough description. Are we talking about a physical mailbox that you'll need to install a sensor or switch in, or an E-mail box? If the latter, there's a tutorial out there, I think on Adafruit's site, to light an LED when you get a new E-mail. Using that code, you're half done. ...
by Tarcas
Fri Jul 18, 2014 8:32 pm
Forum: Automation, sensing and robotics
Topic: Controlling Servos
Replies: 10
Views: 1912

Re: Controlling Servos

Is it servo S that's not working? If so, I'd take a closer look at this line:
s=GPIO.PWM(3100)

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