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Zero-crossing activated relay
Accepted answer
7 votes

You don't need to hack the kernel. You just need to move the process out of the scheduler queue. #include<sched.h> struct sched_param param; param.sched_priority = ...

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How can I use more GPIO ports on the Raspberry Pi?
4 votes

Depending on speed and distance to controlled/controlling devices, you can connect DS2408 to the 1-Wire interface. Each chip provides eight I/O channels. You can attach... many of them. Possibly ...

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Water irrigation system for Raspberry Pi
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2 votes

From hardware side you'll need a relay board (ones for Arduino, e.g. Funduino boards are okay), a solenoid valve, and a power supply capable of driving both RPi and the board - you'll need at least ...

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Pi to Pi communication
0 votes

Since the two RPi's are supposed to move (if I understand correctly) you will need some wireless communication (dragging wires through the maze is not a good idea...). Probably the easiest approach ...

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Need to skip or delete rc.local
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5 votes

One simple approach is to get a PC with Linux (even a LiveCD distribution - Ubuntu allows booting from CD for example) will suffice. Every modern Linux will recognize both SD partitions out of the box ...

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How to wire a stepper motor?
0 votes

First, what power supply are you using? In the config I see, the same Vcc is used to drive the RPi, the motor and the board (jumper shorted). I'm surprised that doesn't reset the Raspberry (drawing ...

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USB-LAN adapter over USB hub
1 votes

Sure you can; you'll need a powered USB hub though, to power up all these adapters, and you'll have a hard time achieving 100mbit throughput. USB 2.0 is 480 Mbit/s half-duplex, over one cable between ...

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How many volts does the Raspberry Pi supply out to the GPIO?
0 votes

Resistor's rated voltage is a distant property of minimal significance, especially in low-voltage applications (<24V). The resistor's primary property is resistance, which, following Ohm's law, ...

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Long (30 to 50 foot) USB power only cable
3 votes

it may introduce a whole lot of inductive noise and depending on your environment it may work or your board may keep resetting or getting all kinds of glitches. (such a cable acts as a huge antenna ...

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How to make a Raspberry Pi touch door switch and logger?
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2 votes

The touch buttons are "active low" so you connect 3.3V to button's VCC, GND to button's GND and any standard GPIO to button's OUT. In your program that is to run this, you configure this to a pulled ...

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Pin current protection circuit
Accepted answer
2 votes

If the only device to receive current from the diode is the voltmeter it is quite likely you get the output voltage on the input side - the diode leakage current is minimal but the voltmeter ...

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How to get more than one uart interface
6 votes

If you decide to skip adding extra hardware and just go the bit-banging route, this isn't as difficult as some picture it. First off, your communication thread must go realtime: #include<sched.h&...

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Adding 5V fan to GPIO 2 and 6
1 votes

If you attached the fan directly between GPIO and GND, you won't get far. These pins can optimistically source up to 50mA at 3.3V, realistically you shouldn't exceed 5mA draw. A really tiny fan can ...

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Using a Console Cable, Error "Could not find PTY", MAC
2 votes

Seems like whatever distribution you're running on Raspberry doesn't have getty or some equivalent attached to the serial port (and the tutorial doesn't as much as mention that necessity). Check /...

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Kernel module assembly output
Accepted answer
1 votes

What is your C compiler? If it's GCC, adding parameters -S -save-temps makes it leave all intermediate files - preprocessed, assembly, objects.

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I think I've deleted the default pi user
3 votes

Connect the SD to a PC running Linux (even a LiveCD distribution - you don't need to install it on your hdd) add pi:x:1000:1000:,,,:/home/pi:/bin/bash to etc/passwd (not /etc of your Linux, but ...

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Auto-refresh for Midori
4 votes

I decided to approach it from a different side, mostly browser-independent. The browser is started in kiosk mode, pointing at a specific local document: watchdog.html <!DOCTYPE html> <html&...

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