PCA9685 not working properly with arduino UNO

Projects General Guidance
22

yep. I checked again

23

I have dug out a PCA9685 board and tried the code in post #2 with a resistor and an LED between pin 1 of the board and its corresponding GND pin and it works fine for me with no external power supply

The only connections to the PCA9685 are VCC, GND, SDA (A4) and SCL (A5)

24

I got out my PCA9685, hooked it up correctly, LED on PWM 1. Programmed it with this code.
LED is one second on, one second off.

#include "Wire.h"
#include "Adafruit_PWMServoDriver.h"

Adafruit_PWMServoDriver PCA9685 = Adafruit_PWMServoDriver(0x40, Wire);

void setup() {
  Serial.begin(9600);
  Wire.begin();
  PCA9685.begin();
  PCA9685.setPWMFreq(1600);  
}

void loop() {

  PCA9685.setPWM(1, 0, 4095);
  delay(1000);
  PCA9685.setPWM(1, 0, 0);
  delay(1000);
}
25

Are these your own pictures?
The third one shows the pin headers not soldered to the board...
Leo..

26

Hi, MrWawa, No these are just pics I found from the online store I bought it from

27

thankyou very much UKHeliBob for helping by checking the code for me, But do you have to use a resistor with the board, doesn't it already have 200 ohm resistors built in

28

200 ohm built in every PWM output. No need for resistor.

29

Thanks very much Mr.SurferTim for your help, really do appreciate it. But in my one it just does not work I also switched out the arduino board to see if that is the problem but still no luck.

30

is there anyway you can send me a picture of the board you used

31

200 Ohms is very low in my opinion and, in any case, the LEDs that I tested it with have a 1K resistor built into their leads

1 Like
32

I'm using that code watching the LED blink.
Are you certain the SDA to A4 and SCL to A5?

33

yea

34

Is anything else connected to the Uno ?

36

No, nothing else connected

37

Do you think all the boards are faulty

38

Guys!! I changed removed the wires I used for the test and added brand new ones and it workkkeeeeddd!!

40

Hi guys! since I was messing with rgb led strips lately smd5050 ones I decided to make like a cool animation using them for my balcony. Each strip need to control is exactly 0.3m long and has 18 LEDs. I need to control 13 of these strips. So, to acheive this I took 13 of uln2003a ICs and one IC controls one LED strip. These ICs are connected 3 PCA9685 board chained together and these boards are connected to arduino uno. To drive these LEDs I have used a cheap 12v 3A power supply. There will be a time during the animation that I need to turn all the strips white colour causing all chanels to be turned on. Now the problem is that when I do so although the LEDs seem to be white they are a bit dim. I tried checking if anything was heating up. The arduino board and all the PCA9685 were not heated up at all and the only thing that was heated up quite a bit was the power supply. What do you guys think I need to fix here? All ideas will be appreciated greatly.

41

18*13 = 234 LEDs. What's the current requirement for each LED? Because 3/234 = 12.8 mA per LED maximum. So I think you're overloading your power supply, if I read your text correctly.

43

Hi Mr. camsysca, thanks for the response about the question you asked here is what I found on the web:
image

44

So, can you do the math? 300 LEDs need 5A, so one LED needs 5/300, or 1/60, = 16.7 mA for full brightness; looked at another way, your 234 LEDs need 234/300 * 5A, or about 3.9 Amperes of current. Clearly, more than the 3A your supply will provide, so you've overloaded it. Usually, such a supply will current-limit, protecting itself by reducing voltage until the 3A is all it's providing. It's called current-foldback. Alternatively, cheap supplies just quit, either outputting nothing until the load is removed, or quitting completely.
Does that help?