PWM hardware used to blink/fan 16 leds with driver

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Thu, 20 Apr 2017 12:17:38 GMT

yes all the random led glowing behaviour was just due to the voltage/current at the input of the driver. anyways, thanks for your time

RE: PWM hardware used to blink/fan 16 leds with driver

ovrebekk — Thu, 20 Apr 2017 11:27:23 GMT

Hi. I am glad you found the issue. I had one of the HW guys look at your schematic and he didn't spot any issues.

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Wed, 12 Apr 2017 12:13:41 GMT

SOLVED-

the problem was with the amount of voltage given to the led driver which resulted into random behaviour of leds, increasing the voltage solved the problem

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Wed, 05 Apr 2017 08:09:40 GMT

I have attached the schema of 4 leds with their 4 drivers. Inputs- PWM1 to 4 are attached to either of the following 4 gpios which i have configured for 16 pwm fan outputs- (P3,4,28,29) or (P19,20,22,23) or (P27,26,2,25) or ( P0,1,21,5). Outputs- OUT1 to 4 are connected to LED Anode with common ground.

drive.google.com/open

thanks

RE: PWM hardware used to blink/fan 16 leds with driver

ovrebekk — Wed, 05 Apr 2017 06:40:01 GMT

In terms of schematics, I was looking for one showing what type of LED driver you are using, and how it is connected to the nRF52832 GPIO pin.

It doesn't have to show all 16 pins, assuming they are all connected in a similar fashion.

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Tue, 04 Apr 2017 10:07:27 GMT

drive.google.com/open

Please find attached a basic schema.

Basically, i have 16 LED- 4 each of R G B W. each led has its own driver, and each driver takes pwm input from 16 gpio outputs of nrf52 as mentioned in the program. As the driver is driven by pwm outputs, when i measure current, my multimeter doesn't shows any current upto 0.000A. Therefore, I assume its much less than 5mA. So that shouldn't be an issue logically. When i run the program and attach all leds to respective pwm, some leds work at full brightness whereas the others at random brightness. I am not able to figure out the issue.

Also one more thing i wanted to know. in the program, I use 4 timers to drive 4 PWM of 4 channels each, thus an output of 16 channels, with each 4 having the same duty cycle. Is it possible to set the duty cycle of each 16 channels separately , and is it possible for seperate playback for each channel on nrf52?

Many thanks in advance

RE: PWM hardware used to blink/fan 16 leds with driver

ovrebekk — Tue, 04 Apr 2017 06:52:31 GMT

If the problem happens when you physically attach more LED's, and not when you add more PWM channels in the software, I would have to assume it is related to the amount of current sourced to each pin.

Have you measured how much current is sourced to each LED?

The nominal source/sink current for each GPIO is only 0.5mA, and if you exceed this then the behavior might be unpredictable.

You can set up to three pins in high drive mode, where you can source/sink up to 5mA, but this doesn't really help if you are trying to use more than 3 pins.

Do you have a schematic or diagram showing how each LED is connected?

Best regards
Torbjørn

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Mon, 03 Apr 2017 12:09:55 GMT

i am using sdk 12.2.0

RE: PWM hardware used to blink/fan 16 leds with driver

ovrebekk — Mon, 03 Apr 2017 12:07:15 GMT

Thanks for the zip. What SDK version are you using?

RE: PWM hardware used to blink/fan 16 leds with driver

akshaey — Mon, 03 Apr 2017 09:27:51 GMT

Hi i have uploaded the zip on drive, link-

drive.google.com/.../view

RE: PWM hardware used to blink/fan 16 leds with driver

ovrebekk — Mon, 03 Apr 2017 09:23:25 GMT

Do you mind zipping your project and attaching it? Then I can more easily test your code.