TLC5940
#1
Posted 02 May 2012 - 06:59 PM
There is already another thread, where I asked for info, http://forums.netdui...h__1#entry18925 but I see that it doesn't come up on the list (maybe it's too old), so I start a new thread here.
I found very difficult even only to understand the needed wiring, so a very very short mini-tutorial would be really appreciated (not only by me, I'm sure...).
Thanks in advance
Andrea
#2
Posted 03 May 2012 - 11:46 AM
That's the way I never bet anything for that chip, at least for the Netduino world.
Just have a look at these chips, for example:
http://www.austriami...iver-ICs/AS1117
They are simply amazing, plus they are cheap (I guess around €5 each).
To drive a similar chip is trivial using Netduino (I didn't try yet though), and it embeds everything you need: led/display drivers, and keypad.
I'm seriously thinking to buy some of these, just to play on...
Cheers
#3
Posted 03 May 2012 - 11:49 AM
My .NETMF projects: .NETMF Toolbox / Gadgeteer Light / Some PCB designs
#4
Posted 03 May 2012 - 12:08 PM
Ohh that AS1117 indeed looks promising! Nice find. Now just need to find a nice shop that sells them
It's just around your corner!
#5
Posted 03 May 2012 - 02:11 PM
#6
Posted 03 May 2012 - 04:32 PM
I found a small but interesting document here: TLC5940 One-Wire Control, where, with an apparently simple wiring, I should be able to turn on and off the entire block of LEDs. The only interesting page is page 3, even if the whole document is there.
I wired the chip in this way:
and used this code to try to get the led flashing:
Thread.Sleep(300); var gsclk = new OutputPort(Pins.GPIO_PIN_D0, false); var blank = new OutputPort(Pins.GPIO_PIN_D1, true); Thread.Sleep(200); bool enable = false; while (enable) { blank.Write(enable); Thread.Sleep(1); gsclk.Write(!enable); Thread.Sleep(2000); enable = !enable; }
Here I'm supposing I can use the Netduino to turn high and low the two signals GSCLK and BLANK, with a simple delay, as suggested by the document (it uses a subcircuit, there).
The other difference is the capacitor in the bottom of the figure, between Vcc and ground: there are no numbers, and I suppose it's there to stabilize input voltage (or not?).
Please, is there someone who can give a look and enlighten me on anything that can be wrong?
Thanks again.
Andrea
#7
Posted 03 May 2012 - 04:40 PM
#8
Posted 03 May 2012 - 04:45 PM
There is error in the code: while(false) never executes the inside code. I have not checked the wiring, though.
bool enable = false; while (enable) { ... }
#9
Posted 03 May 2012 - 04:55 PM
#10
Posted 03 May 2012 - 06:41 PM
#11
Posted 03 May 2012 - 06:56 PM
#12
Posted 03 May 2012 - 10:29 PM
What puzzles me is that I've tried two sources I found in internet:
- http://tlc5490netduino.codeplex.com/
- http://forums.netdui...940-pwm-driver/
but neither one has the wiring diagram. It's really strange that programmers so kind to share their code don't think to inexpert people like me: or I'm so inexpert to not see something obvious... :-)
Everywhere I look I find some different detail, on the wiring, so that it's even impossible to try every combination!
Andrea
#13
Posted 04 May 2012 - 05:28 AM
If you follow the link to the blog in the above forum post you will find the schematic for the circuit. You are right that the post does not contain a Fritzing diagram but the schematic is there.- http://forums.netdui...940-pwm-driver/
but neither one has the wiring diagram.
Regards,
Mark
To be or not to be = 0xFF
Blogging about Netduino, .NET, STM8S and STM32 and generally waffling on about life
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#14
Posted 04 May 2012 - 05:42 AM
Looking at the datasheet this does not appear to be a PWM chip - unless I've missed something. Looks interesting though. I feel a cube controller redesign coming on.Just have a look at these chips, for example:
http://www.austriami...iver-ICs/AS1117
They are simply amazing, plus they are cheap (I guess around €5 each).
Stefan - you can get them from Digikey but they only appear to be available as QFN packages. The AS1115 which is similar is available in an SSOP package.
Regards,
Mark
To be or not to be = 0xFF
Blogging about Netduino, .NET, STM8S and STM32 and generally waffling on about life
Follow @nevynuk on Twitter
#15
Posted 04 May 2012 - 06:51 AM
Looking at the datasheet this does not appear to be a PWM chip - unless I've missed something. Looks interesting though. I feel a cube controller redesign coming on.
Stefan - you can get them from Digikey but they only appear to be available as QFN packages. The AS1115 which is similar is available in an SSOP package.
Regards,
Mark
Well, it depends on what Andrea has in his mind.
From a led-driver perspective (as the TLC is), the AS* do offer a PWM modulation.
BTW, I'm afraid that Andrea is looking for something else than a LED driver.
Cheers
#16
Posted 04 May 2012 - 07:20 AM
#17
Posted 04 May 2012 - 08:27 AM
If you want to run the GSCLK from the Netduino then you will have a slow clock signal which will lead to a very long period for the PWM signal. The NETMF is not fast enough to generate a clock signal for the chip if you want sub 1 second frequencies for the PWM output.Yes, Mark, but in your case I cannot get over the external timer problem: I would like to handle everything from the netduino.
regards,
Mark
To be or not to be = 0xFF
Blogging about Netduino, .NET, STM8S and STM32 and generally waffling on about life
Follow @nevynuk on Twitter
#18
Posted 04 May 2012 - 08:44 AM
#19
Posted 04 May 2012 - 10:46 PM
#20
Posted 09 May 2012 - 10:07 AM
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