Using the four PWM that are suppose to able to work with each hardware PWM!

[Mike_Learning]

I am able to use the 2 channel mode of each PWM giving me a total of six PWM that I can set individual duty cycle PWM!

I now find I need 8 PWM with individual duty cycles! Can anyone point me in the direction has sample code for using them?

 /**  Config is for PWM2 using both PWM channels on pins 24 and 25 with a frequency of 1/(20000uS) = 50Hz   */
     app_pwm_config_t pwm_config1 = {
          .pins              = {24, 25},
          .pin_polarity      = {APP_PWM_POLARITY_ACTIVE_HIGH, APP_PWM_POLARITY_ACTIVE_LOW},
          .num_of_channels   = 2,
          .period_us         = 20000L
      };

And this is were I write the values to the PWM!

while (app_pwm_channel_duty_set(&PWM1, 0, val1) == NRF_ERROR_BUSY); 
   while (app_pwm_channel_duty_set(&PWM1, 1,val2) == NRF_ERROR_BUSY);

Thanks!

[Edvin]

Hello,

What happens if you try to add the last two PWMs the way that you already added the 6 that you currently have?

BR,

Edvin

[Mike_Learning]

This is what I changed it to!

 app_pwm_config_t pwm_config = {
          .pins              = {22, 23, 26},
          .pin_polarity      = {APP_PWM_POLARITY_ACTIVE_HIGH, APP_PWM_POLARITY_ACTIVE_LOW},
          .num_of_channels   = 3,
          .period_us         = 20000L
      };

It locks up when it gets to.

The program fails to responded. And when I try to disconnect from the Nordic UART program the Red connect led stays on solid red. If I comment out this line everything runs!

 while (app_pwm_channel_duty_set(&PWM1, 2, val);

[Edvin]

Hello,

Each app_pwm can have maximum 2 channels. 

You may haven't noticed, but your application asserts because app_pwm_channel_duty_set() -> app_pwm_channel_duty_ticks_set() asserts if channel is greater than or equal to APP_PWM_CHANNELS_PER_INSTANCE, which is 2. 

If you need 8 PWMs you have two options as I see it. Both are described in this post:

https://devzone.nordicsemi.com/f/nordic-q-a/44084/control-6-channel-pwm-at-the-same-time-which-can-modify-duty-cycle-by-app_timer/172846#172846

Best regards,

Edvin

[Edvin]

By the way, you can also use 4 timers and 4 app_pwm instances by using the example that you are already using, but it is very resourceful, and running it, I see a bit of flickering on the LEDs, due to CPU interrupt collisions. I don't know how sensitive the devices you are controlling with your PWM are.

Best regards,

Edvin

[Mike_Learning]

How do you do this? I am using a nRF52832 and it only has the 3 pwm's!

[Edvin]

Hello,

The app_pwm doesn't actually use the PWM hardware peripheral, but it uses timers together with PPI and the gpiote driver to toggle pins. The app_pwm module has some limitations, because it has to consider the amount of CC registers in a timer. The PPI example that is hard coded in the main.c file that I posted in my other link uses TIMER3, which has more CC registers, so it can fit more PWM signals. 

The hardware PWM you can read about here. As you see this supports up to 12 PWM channels. There are 3 PWM hardware peripherals, and they each support up to 4 channels each. 

BR,

Edvin