Several questions for turning LEDs on with PCA9956B

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Several questions for turning LEDs on with PCA9956B

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daehyeonkim
Contributor II

Hello,

I'm using PCA9956B to controll 40pcs of RGB LEDs

I connect 5 of PCA9956B and gave the address(10h, 12h, 14h, 16h, 18h) to them.

then, 8 RGB LEDs is to be connected to each PCA9956B

(because PCA9956B is 24-channel controller, RGB LED has 3-pin)

When I send I2C messages to each addresses I can see the ACK signal on the I2C lines.

So I've tried to turn LEDs on, but it doesn't seem to be working well.

The first thing I've done is that pulling down the /OE pin to ground.

on the datasheet, It is nessesary to make LEDs turning on

then Initialized MODE1 register as default values for unexcepted situations

and change the registers such as LEDOUT, PWM, IREF..

But I can't see any LED lighting.

What I have to check or do I miss something to do here?

Thank for your assistance.

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3 Replies

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darioarias
NXP Employee
NXP Employee

Great! I'm glad you found out what was going on and you were able to solve it, I'm sure your contribution will be helpful for someone else in this community, thank you very much!

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darioarias
NXP Employee
NXP Employee

Hello Daehyeon,

I really would like to know some more details to see what we can do to make it work.

Do you receive an acknowledge after configuring each of the registers?

Do you think you can send me the values you set for each register? or if you can send me the source code would be even more useful.

Finally, Do you think you can share with me the schematic as well?

Thanks a lot!

Dario

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daehyeonkim
Contributor II

Finally I solved that problem and that was a really simple thing.

I missed to send the software reset to each chip.

When PCA9956B is powered on MCU send the software reset via I2C,

every function is working well.

Thank you for your reply.

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