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by PiGraham
Sat Oct 12, 2013 8:28 pm
Forum: Bare metal
Topic: Camera in bare metal
Replies: 5
Views: 1775

Re: Camera in bare metal

I wondered about this myself. A potential benefit could be very fast start-up. There are various possible applications for PiCam where it would be desirable to power on and take a picture within a couple of seconds.
by PiGraham
Fri Oct 11, 2013 7:28 pm
Forum: Camera board
Topic: New version of Raspistill
Replies: 150
Views: 24630

Re: New version of Raspistill

Thanks ethanol100. I have compiled it and it seemed to run on a quick test. -k option, functioned as described below. Mindful of James' remark about latest firmware I updated. I did a rpi-update, built it again. The -k option works, but cycles twice. With %d in the output filename I get two differen...
by PiGraham
Fri Oct 11, 2013 6:54 pm
Forum: Gertboard classic
Topic: Tandy Multiface
Replies: 12
Views: 4365

Re: Tandy Multiface

ReesD wrote:So that's a yes then. :-)
It doesn't look like an exact copy. It has different layout & different connectors.
by PiGraham
Fri Oct 11, 2013 3:36 pm
Forum: General discussion
Topic: Audio Activation Switch
Replies: 14
Views: 1609

Re: Audio Activation Switch

You may be able to get some "now playing" info from the squeezelite server. Can you display what any server is playing from a device other than the one you started the play from? Perhaps you can run a client on the Pi that can monitor what the server is doing and activate a GPIO from there. lcdproc ...
by PiGraham
Fri Oct 11, 2013 2:40 pm
Forum: Automation, sensing and robotics
Topic: Room by Room central heating control
Replies: 31
Views: 28827

Re: Room by Room central heating control

I'm part way through implementing a similar system, and thought I'd mention my approach to the radiator valves, which is slightly different. I'm buying the http://www.conrad-electronic.co.uk/ce/en/product/615952/Honeywell-Rondostat-HR20-Radiator-ThermostatHoneywell HR20 electronic thermostatic valv...
by PiGraham
Fri Oct 11, 2013 2:28 pm
Forum: Automation, sensing and robotics
Topic: Here's my first RPi project: The Yeodem.
Replies: 6
Views: 953

Re: Here's my first RPi project: The Yeodem.

An alternative could be to slightly hack the router hardware. If it has a "connected" LED then the drive to that could trigger something like a 555 to cut power for a few seconds. A 556 dual could provide the 30 minute lock-out as well. (maybe that's pushing it with an RC circuit. 10 mins is suppose...
by PiGraham
Fri Oct 11, 2013 2:21 pm
Forum: General discussion
Topic: Audio Activation Switch
Replies: 14
Views: 1609

Re: Audio Activation Switch

I don't think you can Wake On Wireless on a Pi.

What is playing the stream at the Pi end? You may be able to detect it's status.
by PiGraham
Fri Oct 11, 2013 1:14 pm
Forum: Automation, sensing and robotics
Topic: Here's my first RPi project: The Yeodem.
Replies: 6
Views: 953

Re: Here's my first RPi project: The Yeodem.

gmc wrote:Nice. You could have done the same thing with a 555 timer :D
How does a 555 timer know if the internet is inaccessible?

A change of ISP or a new modem might be better options. ;)
by PiGraham
Fri Oct 11, 2013 12:31 pm
Forum: General discussion
Topic: Dyson design awards
Replies: 0
Views: 276

Dyson design awards

by PiGraham
Fri Oct 11, 2013 12:18 pm
Forum: General discussion
Topic: Audio Activation Switch
Replies: 14
Views: 1609

Re: Audio Activation Switch

Russh wrote:(its will play the audio via its HDMI socket by the way)
So PWM signal is not readily available.
by PiGraham
Fri Oct 11, 2013 11:42 am
Forum: General discussion
Topic: Audio Activation Switch
Replies: 14
Views: 1609

Re: Audio Activation Switch

I assume the OP has audio streaming all the time but it may be quiet, and only want the amp on when the stream is not quiet. I'm not sure why that would be the case, but getting the signal level of the audio output channel seems a good way to go to achieve that. If there is not silent audio streamin...
by PiGraham
Fri Oct 11, 2013 11:06 am
Forum: General discussion
Topic: Audio Activation Switch
Replies: 14
Views: 1609

Re: Audio Activation Switch

This VU meter in Python may give some pointers.
http://freshfoo.com/blog/pulseaudio_monitoring

When the level goes above some threshold level turn on the GPIO to power-up the amp.
by PiGraham
Fri Oct 11, 2013 10:52 am
Forum: Other projects
Topic: Building a Helmet Mounted Camera using a Raspberry Pi
Replies: 6
Views: 1691

Re: Building a Helmet Mounted Camera using a Raspberry Pi

I plan to use a small webcam connected to a Raspberry Pi, then transfered to a small external usb powered Hi Ash, You should look at the RasPi Camera. It is nicely supported for HD video with hardware compression, which means you can have HD video with good compression. You may be looking as a webc...
by PiGraham
Thu Oct 10, 2013 2:17 pm
Forum: Other projects
Topic: Bugblat PIF FPGA board
Replies: 2
Views: 1508

Re: Bugblat PIF FPGA board

Interesting.
Bugsplat sell a logic analyser. You could do something like that with this. Hook it to some ADCs and make a storage 'scope.
Implement some truly hard-realtime motion control.
Audio effects. Interfaces (drive big LED array with precise clocks and buffered data).
by PiGraham
Thu Oct 10, 2013 10:01 am
Forum: Python
Topic: Flashing an LED while code runs
Replies: 1
Views: 529

Re: Flashing an LED while code runs

Perhaps the easiest way is to toggle the LED each time you read the probe.

Code: Select all

...
state = True
while (thermalprobe.read == active):
    GPIO.output(20,state)
    state = not state
The frequency of flash is half the sample rate and no need for delays merely to make the LED visible.
by PiGraham
Wed Oct 09, 2013 8:06 pm
Forum: Graphics, sound and multimedia
Topic: Video on the Pi
Replies: 5
Views: 960

Re: Video on the Pi

Have you had some problem doing this, or are just unsure how to start?
omxplayer provides hardware accelerated decoding of h264 video.
by PiGraham
Wed Oct 09, 2013 10:30 am
Forum: Beginners
Topic: PiFace
Replies: 3
Views: 516

Re: PiFace

You could start with some examples of using the WiringPi library with PiFace. http://wiringpi.com/the-gpio-utility/piface-commands/ http://wiringpi.com/dev-lib/piface/ You can run IDLE on the Pi to start using Python. You could try http://www.codecademy.com/ to learn a bot about Python on-line. You ...
by PiGraham
Wed Oct 09, 2013 8:50 am
Forum: Recommended peripherals
Topic: Hint about frame-grabber
Replies: 11
Views: 6965

Re: Hint about frame-grabber

Oddly there are dvb tuners on the list at http://elinux.org/RPi_VerifiedPeripherals but no video/frame grabbers listed - have to update it The STK1160 Easycap usb grabber works ok, and so does the hauppage hvr1900 http://www.raspberrypi.org/phpBB3/viewtopic.php?t=20838&p=419258 At what resolution a...
by PiGraham
Mon Oct 07, 2013 6:23 pm
Forum: Python
Topic: quadrature problems
Replies: 18
Views: 3989

Re: quadrature problems

by PiGraham
Mon Oct 07, 2013 1:03 pm
Forum: General discussion
Topic: How well can Pi do speech recognition and synthesis
Replies: 9
Views: 7058

Re: How well can Pi do speech recognition and synthesis

Hi Wallhanger, Espeak works easily and fabulously on the Pi for speech synthesis. It is surprisingly good! T o n y Do you get no problems with longer text strings? I find that anything over ~2 seconds the speech breaks up and sounds like a Dalek. This is OK: espeak "This is a short line of text." T...
by PiGraham
Mon Oct 07, 2013 11:41 am
Forum: Media centres
Topic: Digital signage solution feasibility
Replies: 4
Views: 2270

Re: Digital signage solution feasibility

See also:
RasPi Video Wall
http://www.raspberrypi.org/archives/3648
by PiGraham
Sun Oct 06, 2013 11:16 am
Forum: Other projects
Topic: How to read voltage using a Pi
Replies: 15
Views: 30580

Re: How to read voltage using a Pi

A single voltage range is easy enough with a simple voltage divider. Consider what measurement accuracy you need. You may need to use low thermal coefficient resistors to maintain calibration in varying conditions. You should check the tolerance of the voltage reference used by the ADC. You will wan...
by PiGraham
Sun Oct 06, 2013 10:59 am
Forum: Other projects
Topic: Dual Monitors
Replies: 28
Views: 74292

Re: Dual Monitors

Is this relevant?
RasPi Video Wall
http://www.raspberrypi.org/archives/3648
by PiGraham
Sun Oct 06, 2013 10:53 am
Forum: Other projects
Topic: How to read voltage using a Pi
Replies: 15
Views: 30580

Re: How to read voltage using a Pi

Thanks for the help but will using that limit the DC voltage I can measure? What range do you want to measure? You can use a voltage divider, or amplifier, on the input, but you may need more signal conditioning circuitry, depending on the requirements of your application. It would help if you expl...

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