Trouble with the 18-Channel 8-bit PWM LED Driver w/ I2C Interface (SN3218 breakout)


#1

I’ve just received a 18-Channel 8-bit PWM LED Driver w/ I2C Interface that I ordered through amazon and tried about everything I can to get it working.

I have verified that my arduino is working ok and that it can run other i2c devices, I also checked that the LEDs are working too. But I still get nothing more than 0.01/0.02 volts output.

There is power getting to the board (I can get 5 and 1.2 volts probing the chip) and there is continuity between all the output pins (and sn3218 gnd pin) and the arduino gnd. I don’t know what else I could try to get it working. The pictures show my set up.

Pictures: https://www.dropbox.com/sh/6do9c2scv339vvt/AAD5cnhoJB_2BNvFq5b58j4aa?dl=0

Thanks in advance


#2

I knew the answer to this, or at least I hope I did, before I finished reading the title. I’m going to guess it’s because the LED is the wrong way 'round, which is an extremely easy mistake to make since it’s quite disingenuous at first glance.

The PWM LED Driver is a current sink device, that means it connects things like LEDs to ground, and doesn’t actually supply a voltage.

Connect your LED to 5v, connect the other side to one of the PWM driver “outputs” and try again.


#3

Thank you gadgetoid, I thought I had tried that before, but it works perfectly now.


#4

There’s a good reason why I knew the answer, this chip is my arch nemesis… ಠ_ಠ ( I’ve wired it up in all the wrong ways )

Have fun with it!


#5

Thanks, hopefully my word clock won’t be far from completion now!


#6

I am also working on the same. According to me the LED is the wrong way 'round, which is an extremely easy mistake to make and also it is quite disingenuous at first glance.
The PWM LED Driver is a current sink device, that means it connects things like LEDs to ground, and doesn’t actually supply a voltage.
Also try by connecting your LED to 5V, connect the other side to one of the PWM driver outputs.

electronic pcb assembly


#7

The PWM LED Driver is’t actually supply a voltage.

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