Show Posts
Pages: 1 2 [3] 4 5 ... 11
31  Using Arduino / Displays / Re: TVout: NTSC and PAL Composite Video Output. on: July 15, 2011, 10:54:55 am
Very very nice.  That is really awesome work, gijs.
32  Using Arduino / Project Guidance / Re: Monitor the analog signal without loop on: July 12, 2011, 12:59:02 pm
But you can perform the work in loop() and still only do it 3 times.  You are assuming that loop() will always repeat for ever.  But you can prevent it from repeating.  That's why robtillaart told you to use this line:
Code:
for(;;);

Do you understand what this does?  It repeats the line forever, effectively halting the program.  It's like saying "stop".
33  Using Arduino / LEDs and Multiplexing / Re: Double Digit 7-Segment Multiplexing on: July 11, 2011, 02:13:14 pm
@pgmartin,
You could look at the library I provide with the Digit Shield.  I use timer interrupts to automatically handle the multiplexing so that your Arduino sketch can do other useful things without worrying about the timing of the multiplexing.
http://nootropicdesign.com/digitshield/
34  Community / Products and Services / Re: New product: Digit Shield on: July 11, 2011, 12:45:55 pm
@roypogi,

That's great.  I had never thought of using multiple Digit Shields with an Arduino, but one of my customers had proposed the idea, so I enhanced the library to support it.  I've been so happy about the innovation that comes from my customers!

http://nootropicdesign.com/projectlab/2011/05/21/multiple-digit-shields/


35  Using Arduino / Displays / Re: TVout Colors on: July 10, 2011, 06:38:30 pm
Quote
Please elaborate.

What is the difference between PAL and NTSC that makes color output possible?

Read about the project -- he explains it!
http://www.linusakesson.net/scene/phasor/index.php
36  Using Arduino / Displays / Re: TVout Colors on: July 10, 2011, 05:40:39 pm
I know about this demo and it is very impressive.  It takes advantage of a particular feature of PAL, but is not possible with NTSC (North American TV standard).  The memory constraints associated with storing an actual frame buffer (like if you were writing a game or something) are still real constraints.  There are only 2K of SRAM in the Arduino.
Baum, if you think you can use these techniques to make a color version of TVout, then PLEASE do so!  We'd all be very grateful!  We aren't telling you not to try -- we are just informing you of the technology constraints that have made color frame buffer based composite output not possible.  Prove us wrong by doing it!
37  Using Arduino / Displays / Re: TVout Colors on: July 05, 2011, 04:47:23 pm
Quote
Custom hardware

Yes, hardware designed for the purpose of generating video signals.  The ATmega328 is not designed for that.  It's a simple general purpose microcontroller.
38  Community / Products and Services / Re: New product: Digit Shield on: July 05, 2011, 09:31:55 am
@Graynomad: Thanks!  I agree that LEDs are more fun.

@robtillaart: I did not submit it to shieldlist.org, but someone else may have.  The problem is that Jon Oxer has a many-month backlog of shield submissions that have not been posted on the site.  I submitted my Video Experimenter shield in March and it still is not on shieldlist.org!

39  Using Arduino / Displays / Re: TVout Colors on: July 05, 2011, 07:32:15 am
You can't store the frame buffer in flash memory -- it's read-only.
baum, generating color composite video is just not going to happen on a $3 microcontroller. 
40  Using Arduino / Displays / Re: TVout Colors on: July 05, 2011, 06:34:43 am
The Arduino only has 2K of SRAM, so you don't have nearly enough memory to store 8 bits per pixel.  Remember, the memory usage reported by the IDE when you upload is the flash memory for storing your program, not SRAM.

And as AWOL said, there's only so much time to read the pixel information and write to the DAC.  At 128 pixels horizontal, there are only 5 instruction cycles available to do this work, and the current 1-bit output uses 3 cycles (then does a NOP for 2 cycles).  In other words, there's not enough time to even do 2-bit video.
41  Community / Products and Services / Re: New product: Digit Shield on: July 05, 2011, 06:25:56 am
For a limited time, BLUE Digit Shields are available while supplies last.  These are extremely bright and can make your project look great!

More info here

Even though blue 7-segment displays are significantly more expensive than red or green, I'm offering assembled blue digit shields for the same price.

42  Community / Products and Services / Re: Video Experimenter shield on: July 05, 2011, 06:18:59 am
Personally I don't know much about audio processing yet, but I found this very intriguing:
http://interface.khm.de/index.php/lab/experiments/arduino-realtime-audio-processing/
43  Community / Products and Services / Re: Video Experimenter shield on: July 04, 2011, 10:20:18 am
Your idea of guiding a telescope is really cool.  Have you considered feeding the video images somehow to a computer and processing the image with OpenCV code?  That would give you much more power.  The computer could then talk to an Arduino (for example with Firmata) to guide the telescope with servos.
44  Community / Products and Services / Re: Video Experimenter shield on: July 04, 2011, 06:45:48 am
Those microcontrollers have more memory, but it's not as simple as writing a new library.  The Video Experimenter uses features of the ATmega328 that are wired to particular pins.  For example, Arduino digital pin 8 is input capture pin on the ATmega328, and digital pin 2 is an external interrupt pin that the VE uses.  These chip-specific features are probably available on the other Atmel microcontrollers, but not assigned to the same pins.

Also, the video generation and capture routines are written in AVR assembly to get the required perfect timing for video.  Is the Microsoft-based toolchain going to let you write in AVR assembly?  The more you abstract away the details of how things work (the way Microsoft does) the less power you have to do really cool low-level stuff (like capture images in a $3 chip).  Sorry, but I have a bias toward staying close to the hardware and really learning code/electronics versus introducing a vendor-specific framework into the mix.  You'll learn far more with the gcc toolchain that Arduino is based upon.  Just my opinion based on 20 years of software design.  smiley-grin


45  Community / Products and Services / Re: Video Experimenter shield on: July 03, 2011, 07:15:32 pm
It can only be as accurate as the resolution of the display, which is low.  Typically 128x96 or 136x96.  Not sure if that's good enough for tracking stars.  And the tracking is shifted to the right a bit since it takes time to process the image.
Pages: 1 2 [3] 4 5 ... 11