Electronic – arduino – TLC59116F (i2c led driver) everything seems ok but LED doesn’t work

arduinoi2cledpwm

I'm trying the LED driver TLC59116F with an arduino UNO R3. This IC is a i2c controllable LED driver with PWM and 16 outputs. The registers seem all loaded fine, here's a print of their contents:

0:11
1:0
2:C8
3:C8
4:C8
5:C8
6:C8
7:C8
8:C8
9:C8
A:C8
B:C8
C:C8
D:C8
E:C8
F:C8
10:C8
11:C8
12:FF
13:FF
14:FF
15:FF
16:FF
17:FF
18:D2
19:D4
1A:D8
1B:D0

As you can see, all outputs are on C8 (200) which should be high brightness.. and all LED are active I think (the FF registers). I have attached an LED to OUT0 like this:

schematic

^{simulate this circuit – Schematic created using CircuitLab}

If I attach the led to GND instead of OUT0 it (of course) works fine. The IC talks fine on i2c therefore it shouldn't be burnt.. The IC power comes directly from the arduino 5v, which is in turn powered by the USB connection.

Best Answer

The problem was actually very easy, I missed in the datasheet that you need to have a resistor Rext connected to pin 1 - GND, and this resistor defines the maximum output current. Without it no current is outputted, ever.

Related Solutions

Electronic – Algorithm for simulating PWM through 595’s

I am leaning now towards the first one for ease of implementation, but if the second (or some variation on it) has a nice algorithm for different values, then it might be worth looking into.

There is, and it's fairly simple.

Given a duty cycle as a rational fraction p/q between 0 and 1, do the following (pseudo-code in Javascript)

var state = 0;
// q should be a positive constant, but vary p between 0 and q
function pseudopwm(p,q)
{
   state += p;
   if (state < q)
      return 0;
   state -= q;
   return 1;
}

More info in a blog entry I wrote.

To get 16 distinct brightness levels, I need 16 times that number, right?

Sort of. The human perception of brightness is close to logarithmic, so the perceived difference between 0 and 1/16 duty cycle is huge, whereas the perceived difference between 15/16 and 16/16 duty cycle is very small.

Electronic – ArduinoISP fails with Atmega368, 168 – Device signature = 0x000000

The only thing that worked for me was to follow this tutorial: http://3g1l.com/blog-burn-bootloader-blank-atmega328atmega328p-arduino-uno

One very important note: Even though the tutorial concentrates on the minimal setup, for some chips (depending on the supplier) it works ONLY WHEN you add the external oscillator and the two 22pC.

The tutorial also shows a 10k resistor between reset and 5V rail. The missing components might make your setup(the one from your picture) work too. Many users stated in their comments that they got the exact same error as you until they added the oscillator: this might be it!!!

Hope it helps - I struggled for a day before finding this

Best Answer

Related Solutions

Electronic – Algorithm for simulating PWM through 595’s

Electronic – ArduinoISP fails with Atmega368, 168 – Device signature = 0x000000

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