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by liudr
Sun Jun 09, 2013 7:40 pm
Forum: Beginners
Topic: Restoring SD card from backup made using dd
Replies: 13
Views: 10568

Re: Restoring SD card from backup made using dd

dd'ing a smaller image to a larger card is not that hard to do directly, then all you have to do is expand the file system with the regular Raspbian tools or with fdisk or parted with other systems. But I am talking Linux, do not know what a DOS box would do. I installed Debian on an older laptop w...
by liudr
Sun Jun 09, 2013 4:05 pm
Forum: General discussion
Topic: Few questions before purchase..
Replies: 10
Views: 1736

Re: Few questions before purchase..

I recommend you to get an Arduino UNO and connect it to pi's USB. Arduino UNO is 5V logic and has sufficient drive current (40mA per pin) for most sensors. There are countless hardware and libraries for Arduino to talk to sensors and control relay is pretty easy. Thank you. I have an Arduino UNO. I...
by liudr
Sun Jun 09, 2013 3:56 pm
Forum: Beginners
Topic: Restoring SD card from backup made using dd
Replies: 13
Views: 10568

Re: Restoring SD card from backup made using dd

Hi dxradio33, I am trying to make backup of my pi as well. The program that you are recommending, HDD GURU, can it image original image to a larger SD card? I have a 4GB sd card on my pi (initially thought that's enough for a try). Now I am thinking about expanding to 8-16GB card. But I will make a ...
by liudr
Sun Jun 09, 2013 5:06 am
Forum: General discussion
Topic: Few questions before purchase..
Replies: 10
Views: 1736

Re: Few questions before purchase..

I recommend you to get an Arduino UNO and connect it to pi's USB. Arduino UNO is 5V logic and has sufficient drive current (40mA per pin) for most sensors. There are countless hardware and libraries for Arduino to talk to sensors and control relay is pretty easy.
by liudr
Sun Jun 09, 2013 3:01 am
Forum: General discussion
Topic: Help needed to wire a 20x4 hd44780 lcd for use with LCDproc
Replies: 5
Views: 2690

Re: Help needed to wire a 20x4 hd44780 lcd for use with LCDp

What adafruit tutorial and that other tutorial did was total disregard of the specification of the display. According to the spec sheet, logic level is 0.7*VDD minimal. VDD is 5V typical. So if you power the LCD with 5V, your logic HIGH has to be over 0.7*5=3.5V>3.3V. So pi's logic HIGH is not high ...
by liudr
Sat Jun 08, 2013 10:33 pm
Forum: Troubleshooting
Topic: Bricked RPI?
Replies: 11
Views: 5710

Re: Bricked RPI?

Can you post a diagram of your wiring? Have you got a diode to bypass back emf?
by liudr
Sat Jun 08, 2013 7:49 pm
Forum: Other projects
Topic: Connect small lcd screen
Replies: 4
Views: 1491

Re: Connect small lcd screen

It is almost impossible to connect to a proprietary LCD since their spec sheets are never published. If you don't find a spec sheet on the exact LCD, you can't connect it to anything else. If you really want a small display, look for some car lcds on ebay with composite inputs.
by liudr
Sat Jun 08, 2013 7:33 pm
Forum: Other projects
Topic: Mini display
Replies: 9
Views: 2369

Re: Mini display

go to ebay.com and search lcd car.

There are lots of analog lcds for cars. They are easy to hook up to pi since they run composite videos and they come in all sizes and are cheap. You could even play sound on some of them.
by liudr
Sat Jun 08, 2013 7:25 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Push buttons - should I be using a resistor or not? (yes)
Replies: 24
Views: 72048

Re: Push buttons - should I be using a resistor or not?

Interesting. I understand all the reasons here. How do you enable and disable internal pull-up and pull down resistors? I am still learning Pi. For a simple setup the OP is doing enabling internal pull-up would be sufficient even if it is a 50K. 1.8Kohm seems pretty strong pullup for I2C. Was there ...
by liudr
Sat Jun 08, 2013 4:26 pm
Forum: Beginners
Topic: [Solved] Noob trying to communicate with serial port
Replies: 8
Views: 2633

Re: Toe walking? Noob trying to communicate with serial port

Thanks DrMag. Screen is a pretty neat tool for what I am doing.
by liudr
Sat Jun 08, 2013 4:22 pm
Forum: Beginners
Topic: How to startx from remote machine?
Replies: 10
Views: 24422

Re: How to startx from remote machine?

I used ssh -X to connect to pi and did lxsession. It kind of works. A task bar shows up on my Debian box, blocking its original task bar (annoying) I can do everything except showing the "start menu" or seeing the pi desktop. I could do file manager and find the desktop though :) Some error messages...
by liudr
Sat Jun 08, 2013 3:38 pm
Forum: Beginners
Topic: How to startx from remote machine?
Replies: 10
Views: 24422

Re: How to startx from remote machine?

The blink example code in arduino compiles in 30 seconds (compared with 3 seconds on my Debian box with Core 2 Duo 2.4GHz and 3GB RAM). It uploads just fine and Arduino is blinking an LED :) I think I will now be able to develop code, both arduino and c/c++ on Debian, on my Debian box, and then copy...
by liudr
Sat Jun 08, 2013 3:28 pm
Forum: Beginners
Topic: How to startx from remote machine?
Replies: 10
Views: 24422

Re: How to startx from remote machine?

Thank you everyone. I tried in my Debian box to ssh with -X option to open X11 forwarding and then ran Arduino IDE by typing:

Code: Select all

arduino&
The process was pretty slow to start but once it started it was alright. Opening another program in Arduino was acceptable in speed.
by liudr
Sat Jun 08, 2013 6:16 am
Forum: General discussion
Topic: STICKY: Introduce yourself!
Replies: 3654
Views: 192793

Re: Introduce yourself!

Hi I am liudr, I guess another physicists by profession. Not nearly 85 in decimal system yet ;) I am here to learn how to use the raspberry pi and linux. My background is C/C++, Arduino, and Processing.
by liudr
Sat Jun 08, 2013 6:10 am
Forum: Beginners
Topic: How to startx from remote machine?
Replies: 10
Views: 24422

Re: How to startx from remote machine?

Thanks malakai. I downloaded mbaxterm on my pc and it does exactly what you said. On the other hand, I originally wanted to remote login from a Debian machine to pi. I couldn't startx. Should I do lxsession& instead? That machine is turned off so I will try tomorrow. What is the difference between s...
by liudr
Sat Jun 08, 2013 2:31 am
Forum: Beginners
Topic: [Solved] Noob trying to communicate with serial port
Replies: 8
Views: 2633

Re: Toe walking? Noob trying to communicate with serial port

Thanks DrMag. I installed screen on both pi and a debian I just installed on a spare machine :) So how do I quit from the screen? The man page is hard to understand. I think I stopped a connection but now I don't know how to restore it or kill it. Now if I connect to arduino I don't get and echo any...
by liudr
Sat Jun 08, 2013 2:15 am
Forum: Beginners
Topic: How to startx from remote machine?
Replies: 10
Views: 24422

How to startx from remote machine?

Total noob question: to access my raspberry pi I installed Debian on my spare machine. I thought I could SSH to pi and startx to see graphical interface of the pi. The terminal window just hangs with the following message and no graphical interface came up :lol: So how do I bring up the GUI on my re...
by liudr
Fri Jun 07, 2013 6:41 pm
Forum: Beginners
Topic: [Solved] Noob trying to communicate with serial port
Replies: 8
Views: 2633

Re: Toe walking? Noob trying to communicate with serial port

Thanks. I am using raspbian. I tried sudo. The command simply does not exist. Any way to install this command in raspbian?
by liudr
Fri Jun 07, 2013 6:27 pm
Forum: Beginners
Topic: Run out of space
Replies: 4
Views: 1092

Re: Run out of space

I just checked mine. I upgraded and installed Arduino IDE. I have 1.7 GB left. Are you using df to dee free space? I am new to linux and just googled what command to use.
by liudr
Fri Jun 07, 2013 4:42 am
Forum: Other projects
Topic: Powering Pi with LM7805 (solved)
Replies: 21
Views: 13343

Re: Powering Pi with LM7805 (solved)

I've used a cheap UBEC along with an 18V battery from a cordless drill, worked for about 12-14hrs as an wireless AP. Now that beats my ipad :) Thanks everyone for this thread. I bookmarked the drop-in replacement for 7805 (kind of expensive). I'm only starting to use pi but will certainly appreciat...
by liudr
Fri Jun 07, 2013 4:19 am
Forum: Beginners
Topic: [Solved] Noob trying to communicate with serial port
Replies: 8
Views: 2633

[Solved] Noob trying to communicate with serial port

[Update] I think the best way is to install and use screen if you want to communicate with Arduino via serial port on command line. I feel like that I am walking on my toes, like a baby not knowing the best way to walk. Here is my problem and I toe walked to the answer: I connected an Arduino to a P...
by liudr
Fri Jun 07, 2013 2:19 am
Forum: Automation, sensing and robotics
Topic: Ideas sought for counting vehicles...
Replies: 12
Views: 7874

Re: Ideas sought for counting vehicles...

I think both PIR and sonic rangers are out of the question. In an outdoor and noisy environment PIR gets flooded by the sun (it is personnel sensor anyway, not for objects), and sonic rangers get overloaded by the traffic noise. If you can't afford to dig holes on the ground and bury induction senso...
by liudr
Thu Jun 06, 2013 9:15 pm
Forum: C/C++
Topic: Developing code in linux PC and compiling source on pi?
Replies: 6
Views: 2570

Re: Developing code in linux PC and compiling source on pi?

Thanks everyone for confirming that it will work! So for a decent IDE to do c/c++, any recommendations? I am used to the old-fashion turbo-C/C++ so something minimal looking would help me ease my anxiety. On PC I have used Bloodshed Dev C++ for a while (gcc). I imagine Eclipse will work just fine bu...
by liudr
Thu Jun 06, 2013 9:09 pm
Forum: Beginners
Topic: Display information not found
Replies: 2
Views: 622

Re: Display information not found

Thanks. I will try it once I get home. Should I use 82 or 0x52 for display mode or does it not matter?
by liudr
Thu Jun 06, 2013 5:48 pm
Forum: Automation, sensing and robotics
Topic: Raspberry Pi i2c doesn't detect BMP085 sensor.
Replies: 18
Views: 5294

Re: Raspberry Pi i2c doesn't detect BMP085 sensor.

Did you read my reply? Your connections to the sensors need to be soldered. You can NOT just stab the holes with jumper wire leads. Is that so hard to understand?

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