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Topic: Library for TLC5940 16-channel PWM chip (Read 35 times) previous topic - next topic

acleone

@bensaddiction: Very weird.  I don't have a Mac to test on, but can anyone else reproduce this?  Try reinstalling Arduino and then the library.

diode

Hi, would anyone know what the maximum amount of tlc5940's that you can daisy chain is?
I'd like to go upto 68 or 12, but read elsewhere that +10 is problematic?
Thanks!

Chronoless

I've just finished a project with 12 daisy-chained TLC's. I'll put the project online next week. In my case I had each TLC on a separate board. The 12 boards were connected with 11x 20 cm ribbon cable. This gave me some problems with the signal after the 10th board. Because the boards go in a circle, instead of letting the signal travel from the source to the 12th (and back) I was able to split it so I had 0 - 5 and 6 - 11 for all the signals except for SOUT - SIN. That worked ok for me. But I don't think you'll have this problem when you put them all on one board.

andrewoke

Where did you get the TLC's? Digikey is backordered until Sept. 14 and I can't find any elsewhere.

Can't wait until you put it online.

Chronoless

#214
Aug 20, 2009, 11:08 pm Last Edit: Aug 21, 2009, 08:55 pm by Chronoless Reason: 1
I got them (5940pwp (smd)) from rsonline.nl.
You can only order there as a company (b2b).

diode

Thanks Chronoless, 12 sounds great.
Would you think there will be issues to control 6 arduinos with each 11 TLC5940's on them?

Chronoless

When your plan is to control the 6 arduinos through usb than that shouldn't be a problem. But make sure that the configured baudrate is sufficient for your application. But that all depends on the resolution mode (256 (8bit) or 4096 (12bit)) and desired refresh rate.

diode


joe912

has anyone used the tlc5940 with i2c at the same time.  im trying to and getting corrupt data when receiving.  Serial works just fine at speeds of 115200 but i2c does not work.

kivao

#219
Sep 11, 2009, 11:21 pm Last Edit: Sep 11, 2009, 11:22 pm by kivao Reason: 1
I'm having some annoying probs here. I've connected the 5940 to my arduino NANO according to the schematic, triple-checked everything, but the leds still won't light. The problem seems to be voltage on the outputs. My multimeter reads about 0.2 V when i'm pumping 4000 on the channels. When alternating (slow blinking) the result is the expected (0V, 0.2V, 0V, 0.2V etc).
My usb supply voltage is 4.5V, could that have anything to do with it?

joe912

the tlc does not source current it sinks it

so the setup needs to be

+--- LED --- TLCinput
also be sure your using the correct resistor value

kivao

Yeah, thanks, just found out myself. Apparently I hadn't tripled checked the schematic thoroughly enough.  :D Feel as stupid as can be.

Nachtwind

is it possible to turn off a pin so that it is used as GND for a LED?
Believe me, Mike, I calculated the odds of this succeeding against the odds I was doing something incredibly stupid[ch8230] and I went ahead

joe912

just assign the value of 4095 to the correct pin.
this should result in the led being constantly on.

Nachtwind

its not about constantly turning on a led but rather using a pin of the TLC as GND for multiplexing stuff...
Believe me, Mike, I calculated the odds of this succeeding against the odds I was doing something incredibly stupid[ch8230] and I went ahead

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