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by rpdom
Sat Mar 16, 2013 4:37 am
Forum: Beginners
Topic: Problem with New PI
Replies: 5
Views: 809

Re: Problem with New PI

Try another power supply. 700mA is the minimum recommended rating, and a lot of supplies claim they can give that but the voltage will drop if you get anywhere near drawing that much. (I have a no-name supply supposedly rated at 5V 1000mA, but the voltage drops to 3.6V when I draw just 500mA from it...
by rpdom
Fri Mar 15, 2013 7:45 pm
Forum: Other projects
Topic: Raspberry pi as a Wake on Lan source
Replies: 65
Views: 81271

Re: Raspberry pi as a Wake on Lan source

Did you use the command in the format:

wakeonlan aa:bb:cc:dd:ee:ff:gg

Where aa:bb:cc:dd:ee:ff:gg is the MAC/hardware address of the machine to wake?

I just did

Code: Select all

pi@raspi1:~$ wakeonlan 00:50:8d:51:40:41
Sending magic packet to 255.255.255.255:9 with 00:50:8d:51:40:41
by rpdom
Fri Mar 15, 2013 5:09 pm
Forum: Other projects
Topic: Raspberry pi as a Wake on Lan source
Replies: 65
Views: 81271

Re: Raspberry pi as a Wake on Lan source

On the Pi:

sudo apt-get update (just to make sure the software index is up to date)
sudo apt-get install wakeonlan
by rpdom
Fri Mar 15, 2013 7:10 am
Forum: C/C++
Topic: GPIO pins, wiringpi and pin locations
Replies: 3
Views: 3738

Re: GPIO pins, wiringpi and pin locations

Hi, You seem to have all the right details on your web site. The pin numbering you give is correct. Here is a list of the standard functions for each of the pins on the P1 GPIO connector: Pin - Function(s) 1 = 3.3 volt power 2 = 5 volt power 3 = GPIO 2 used as SDA 4 = 5 volt power 5 = GPIO 3 used as...
by rpdom
Fri Mar 15, 2013 6:28 am
Forum: Beginners
Topic: Additional Power led
Replies: 3
Views: 420

Re: Additional Power led

THDG90 wrote: can someone point me to a list of all the pins on the Pi and what they do? (Google did not find anything for me :( )

Thanks.
There's a list of the pins on the wiki at http://elinux.org/Rpi_Low-level_peripherals

Make sure you refer to the Rev. 2 definitions, as you have a Rev. 2 board :)
by rpdom
Thu Mar 14, 2013 3:40 pm
Forum: Advanced users
Topic: Use Pi to automatically program Sd cards
Replies: 3
Views: 834

Re: Use Pi to automatically program Sd cards

I'd be tempted to use udev rules to trigger a bash script that did something like: Turn LED off (if on) Write image: dd if=ImageFile of=/dev/sda bs=1m Verify Image: dd if=/dev/sda bs=1m count=Size | sha1sum Eject sdcard: eject /dev/sda Turn LED on exit You could also add stuff to expand the root par...
by rpdom
Thu Mar 14, 2013 1:32 pm
Forum: General discussion
Topic: how to suspend/restart ?
Replies: 3
Views: 2789

Re: how to suspend/restart ?

To save 90%+ of power - turn off screen and leave RPi on :)

Example: One of my screens (old 15" LCD) uses 39W when active. The Pi uses 3W. So the screen takes 93% of the total power.
by rpdom
Wed Mar 13, 2013 7:53 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Pins registering input when I touch the pin / attach a wire.
Replies: 5
Views: 1096

Re: Pins registering input when I touch the pin / attach a w

How have you wired the button to the pin? Button between pin and 0v or button to 3.3v?

Have you used a pull up/down resistor, or configured the internal pull-up/down resistors?
If not, the pin will "float" with random values and you touching it may be enough to trigger it with leakage current.
by rpdom
Wed Mar 13, 2013 6:54 pm
Forum: Bare metal, Assembly language
Topic: Set screen resolution
Replies: 9
Views: 11874

Re: Set screen resolution

I haven't tried your code, but I've been having a real headache trying to set up the Frame Buffer the way I want it. Finally got it cracked (the code, not my head) I think and have been running at various resolutions (up to the 1024x768 that my monitor supports), at 16, 8 and even 4bpp :-) Next chal...
by rpdom
Wed Mar 13, 2013 2:09 pm
Forum: General programming discussion
Topic: Row/columns for text mode app?
Replies: 5
Views: 796

Re: Row/columns for text mode app?

In bash you can use the shell variables LINES and COLUMNS to see how big the current screen/window is.
by rpdom
Tue Mar 12, 2013 5:02 pm
Forum: General discussion
Topic: Larger boot partition wanted
Replies: 19
Views: 6431

Re: Larger boot partition wanted

Use a USB memory stick formatted to FAT32. Easiest way to do it.

Alternative is using Samba to create a MS compatible shared area.
by rpdom
Tue Mar 12, 2013 2:08 pm
Forum: Other programming languages
Topic: php -v not working
Replies: 1
Views: 918

Re: php -v not working

You have installed PHP for a web server. That is fine if that is what you need to run.

If you want to be able to use PHP scripts from the command line, you need to install php5-cli. Then 'php -v' will work :)
by rpdom
Tue Mar 12, 2013 2:06 pm
Forum: Troubleshooting
Topic: Can't get O/S to boot on new ras pi
Replies: 10
Views: 1573

Re: Can't get O/S to boot on new ras pi

It's silly that some SD cards work and some don't, if you have sata connection on your pc you can go and buy any sata drive and it works . I wish! My PCs mostly only support SATA-1 at 150Mb/s. Stick a 300Mb/s or 600Mb/s drive on t and it won't work at all - unless you get one of the old ones with a...
by rpdom
Tue Mar 12, 2013 9:40 am
Forum: General discussion
Topic: RPi doesn't start with external HDD
Replies: 17
Views: 2442

Re: RPi doesn't start with external HDD

RaTTuS wrote:from that image you are powering the HD from the +5V GPIO pin.
this pin cannot transmit lots of amps,
It looks to me like the 5V is feeding IN to the GPIO pin from the PSU?
by rpdom
Tue Mar 12, 2013 8:51 am
Forum: General discussion
Topic: RPi doesn't start with external HDD
Replies: 17
Views: 2442

Re: RPi doesn't start with external HDD

The Pi needs more current when booting and the HD needs more current when spinning up. If you reboot the HD is already spinning so then the total system will draw less power. Most likely your PSU is not powerful enough. Possibly add a switch between the Pi and PSU, so the HD can spin up first? Migh...
by rpdom
Mon Mar 11, 2013 9:37 pm
Forum: Raspbian
Topic: Can we reconsider the hardfloat ABI?
Replies: 17
Views: 4221

Re: Can we reconsider the hardfloat ABI?

jamesh wrote:Indeed - the correct fix is a HF version of Mono, not a retrograde step to SF Raspbian.
+3.14
by rpdom
Mon Mar 11, 2013 11:15 am
Forum: Troubleshooting
Topic: booting up pi but nothing showing up on screen
Replies: 7
Views: 2878

Re: booting up pi but nothing showing up on screen

It sounds like your Pi is booting up correctly (green light flickering for some seconds), but the display output is incorrect. The first place you should look is http://elinux.org/R-Pi_Troubleshooting#Display As MaxK1 said, what sort of display do you have HDMI, Composite/RCA or something else conne...
by rpdom
Sun Mar 10, 2013 6:21 am
Forum: Other projects
Topic: power consumption?
Replies: 1
Views: 549

Re: power consumption?

8 Watt: 8W / 12V = 0.667A = 667mA. 6800mA / 667mA = 10.19. So it should last just over 10 hours when fully charged under perfect conditions. 3W / 12V = 0.25A = 250mA. 6800mA / 250mA = 27.2 : just over 27 hours. 2W / 12V = 0.167A = 167mA. 6800mA / 167mA = 40.7 : over 40 hours. This assumes the batter...
by rpdom
Sat Mar 09, 2013 7:30 pm
Forum: General discussion
Topic: Keyboard and mouse with raspberry pi model a.
Replies: 4
Views: 1840

Re: Keyboard and mouse with raspberry pi model a.

You really should use a USB hub with its own power supply. The Pi isn't designed to supply more than the minimum power requirements for USB.

Having said that, some keyboards and mice don't seem to work with the Pi :(
by rpdom
Sat Mar 09, 2013 7:22 pm
Forum: General programming discussion
Topic: crontab does not work?
Replies: 26
Views: 27681

Re: crontab does not work?

I'm not sure, but I don't think */5 is valid time reference for cron. The first parameter is the clock minutes for the scheduled task. For example, I have a task that runs my reboot script every half hour by: 30 * * * * /home/pi/rboot.sh */5 is perfectly valid. It means "run every 5 minutes" 30 mea...
by rpdom
Sat Mar 09, 2013 8:14 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Calculating current draw
Replies: 3
Views: 1042

Re: Calculating current draw

Could be worse...

If you used a linear regulator (like a 7805 or similar), it would draw 1A at 12V to provide 1A at 5V. That would be taking 12W from your battery and giving off the 7W difference as heat!

Using that type of regulator the 100 AmpHour battery would last 100 hours at most :(
by rpdom
Sat Mar 09, 2013 7:38 am
Forum: Off topic discussion
Topic: Optocouplers and Opto-isolators??
Replies: 4
Views: 1327

Re: Optocouplers and Opto-isolators??

Hmm, I could probably pop into the local Maplin (about 40 minute walk), buy the 2 they have in stock (allegedly) and post them to you for less than they charge on ebay. Those delivery charges are stupidly high :(
by rpdom
Sat Mar 09, 2013 7:30 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Calculating current draw
Replies: 3
Views: 1042

Re: Calculating current draw

You will get a little less than 1200 Watt Hours due to losses in the step-down regulator. A decent one (switched, rather than linear) should be about 85-90% efficient, which gives you about 1000 Watt Hours. If the RPi is using 1A at 5V, which is 5 Watts as you said, then the regulator will draw abou...
by rpdom
Fri Mar 08, 2013 4:17 pm
Forum: Staffroom, classroom and projects
Topic: kitting out a classroom
Replies: 128
Views: 38118

Re: kitting out a classroom

How old is the Raspbian image the "known good" card was created from?

Some of the older firmware (from the 256MB model B days) isn't compatible with the newer 512MB versions.

It might be worth downloading a fresh image and trying that.
by rpdom
Fri Mar 08, 2013 3:08 pm
Forum: Beginners
Topic: A/V Connection to old TV without HDMI
Replies: 5
Views: 3624

Re: A/V Connection to old TV without HDMI

In Tips and Solution from Sony's link stating that: "SCART (RGB), S-video and Composite are not able to transmit high-definition signals. However, SCART delivers a better picture than S-Video. S-video delivers a better picture than composite". Ur link will work. That quote can be slightly misleadin...

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