HardwareArduino

 

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 From:  Chris (CHRISSS)  
 To:  CHYRON (DSMITHHFX)     
40898.242 In reply to 40898.234 
Could be fun to try it. Might depend if I'm in the mood for a full body search or not.

Me
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 From:  Chris (CHRISSS)  
 To:  ANT_THOMAS      
40898.243 In reply to 40898.240 
I've just been playing with the PWM output with my LED strips. I cut off a small section to test with the Uno.

There's a library called PWM which lets you choose any frequency. I set the frequency to 2000Hz and the flicker at the lowest brightness was almost undetectable. At 20,000Hz (I didn't test anything in between) it had completely gone.

If you have problems with flicker give that a go. I'm now thinking it might be worth setting up an Arduino to control the lights as I don't really like the flicker at low brightness and it would be nice to get rid of it.

Me
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 From:  ANT_THOMAS   
 To:  Chris (CHRISSS)     
40898.244 In reply to 40898.243 
Very useful to know. I did wonder about PWM frequency.

Have you got a link to that library? I'm just using analogWrite at the moment.
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 From:  koswix  
 To:  Chris (CHRISSS)     
40898.245 In reply to 40898.243 
Something I discovered recently (may not be of any use to you but probably handy to know). The Arduino has 6 PWM pins, controlled by 3 timers. Now obviously each *pin* can be set to a seperate duty cycle (0 - 255), but also each *timer* can be set to a separate frequency. So, if you need it for anything, you can have 3 different PWM frequencies, but each pair of pins shares that frequency. There's also some other PWM modes ( http://playground.arduino.cc/Main/TimerPWMCheatsheet ) that may be useful to know.

Makes it possible to control your LEDs with a high frequency, but also if you need to run something else lower, say a motor or something, you can do that to. Don't know if you can use that library to control it (probably, not looked) but you can control it directly from the arduino with the right commands (see link above).

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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.
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 From:  ANT_THOMAS   
 To:  koswix     
40898.246 In reply to 40898.245 
I read something about the PWM timers being different where one is better to use than another. I'll try and find where I saw that.
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 From:  Chris (CHRISSS)  
 To:  ANT_THOMAS      
40898.247 In reply to 40898.244 
It's this: https://code.google.com/p/arduino-pwm-frequency-library/

Me
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 From:  Chris (CHRISSS)  
 To:  koswix     
40898.248 In reply to 40898.245 
I'd read something about the separate timers on the Arduino but hadn't really taken much notice of it. Not sure yet if it would be handy yet but quite possibly at some point.

I had a quick look at that library and looks like it can change all the timers.

It also allows for up to 16bit resolution instead of just the 256 values. Depends on the frequency though, resolution goes down with increased frequency.

Me
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 From:  koswix  
 To:  Chris (CHRISSS)     
40898.249 In reply to 40898.248 
That 16-bit resolution thing - that could be what Ant was on about. Is it only one that supports 16-bit and the other two are 8-bit? Clutching at straws in my memory here, and I only read it last week :$

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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.
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 From:  Chris (CHRISSS)  
 To:  koswix     
40898.250 In reply to 40898.249 
Yeah, looks like timer 1 can do 16bit but the other two only 8bit.

Me
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 From:  ANT_THOMAS   
 To:  Chris (CHRISSS)     
40898.251 In reply to 40898.247 
Thanks. I don't really care about having too many degrees of PWM. 0-255 is fine by me. Realistically 0-9 would do the job for the set brightnesses but would look crap for fading.
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 From:  Chris (CHRISSS)  
 To:  ANT_THOMAS      
40898.252 In reply to 40898.251 
No problem. I was surprised how high the frequency had to go to not notice any flicker at all.

I waved my little strip around (YJ) and took a picture of it.

Me
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 From:  Chris (CHRISSS)  
 To:  ALL
40898.253 
I've just installed the Android Arduino IDE. Maybe not a good idea, I'll never get anything done if I can work on projects with my phone. Uploaded the blink sketch to my Uno and it worked perfectly.

Me
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 From:  ANT_THOMAS   
 To:  ALL
40898.254 
Shift registers and power supply have arrived so I'll be figuring them out tonight.
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 From:  koswix  
 To:  ALL
40898.255 
Floppy Organ now makes recognisable notes!

Learnt how to use interrupts tonight. Quite pleased with the progress, even though there's a lot still to do.
Floppy Organ stage 3: http://youtu.be/obYuROTBXu8

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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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 From:  koswix  
 To:  ANT_THOMAS      
40898.256 In reply to 40898.254 
Saw some PCBs that a guy had made today by seeed, they looked pretty nice.
http://www.seeedstudio.com/blog/2011/05/04/fusion-pcb-service-upgraded-with-even-lower-pricing/

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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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 From:  Chris (CHRISSS)  
 To:  ANT_THOMAS      
40898.257 In reply to 40898.254 
How do PWM outputs work with a shift register? Anything special needed for that?

Me
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 From:  ANT_THOMAS   
 To:  koswix     
40898.258 In reply to 40898.256 
Whilst you have to order a minimum of 5 them prices are actually fairly reasonable.
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 From:  ANT_THOMAS   
 To:  Chris (CHRISSS)     
40898.259 In reply to 40898.257 
I'm using the ShiftPWM library and they seem to work really nicely.

Any flickering has totally gone now I'm using the shift registers. Still figuring out how to use 2 daisy chained together properly.

I was easily able to convert my existing sketch to make use of the shift registers.

rather than:

analogWrite(ledPin1,255);

it is just:

ShiftPWM.SetOne(1, 255);

with the 1 being pin 1 on the shift register. Then you just cycle/loop like any other PWM loop example.
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 From:  koswix  
 To:  ANT_THOMAS      
40898.260 In reply to 40898.258 
Think he said he paid £10 for ten boards. Pretty small boards, but still.

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If Feds call you and say something bad on me, it may prove what I said are truth, they are afraid of it.

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 From:  ANT_THOMAS   
 To:  koswix     
40898.261 In reply to 40898.260 
It looks like about 70 USD for 5 15x20cm boards which is fairly reasonable.

I probably won't need a board that size once I actually draw out the circuits properly.
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