PWM drive: how to generate PWM signals that are phase shifted 90 degree

RE: PWM drive: how to generate PWM signals that are phase shifted 90 degree

t_m — Fri, 15 Feb 2019 14:38:03 GMT

That is right!

Thank you Hakon.

But I still want to understand how to set my duty cycle correctly for any other value than the usual 25%, 50%, 75%..etc. If I understood it correctly, the 0x8000 HEX value is the max. value of the CCR register (2^15).

RE: PWM drive: how to generate PWM signals that are phase shifted 90 degree

Hakon — Fri, 15 Feb 2019 13:02:11 GMT

static nrf_pwm_values_individual_t /*const*/ seq_values[] =
{
    { 0x8000, 0x8000, 0x8000,      0 },
    { 0x8000, 0x8000,      0, 0x8000 },
    { 0x8000,      0, 0x8000, 0x8000 },
    {      0, 0x8000, 0x8000, 0x8000 }
};

With this matrix, all the channels will be phase shifted 90 degrees to each other and have 25 % duty cycle.

RE: PWM drive: how to generate PWM signals that are phase shifted 90 degree

t_m — Fri, 15 Feb 2019 12:13:48 GMT

Hi Thanks...

I just checked that using the oscilloscope and they look 90 degree shifted. But, I just realized that I am not getting a 25% duty cycle that I desired. I tried to put the following in the seq_values[]:

 static nrf_pwm_values_individual_t /*const*/ seq_values[] =
    {
        { 0x2000,      0,      0,      0 },
        {      0, 0x2000,      0,      0 },
        {      0,      0, 0x2000,      0 },
        {      0,      0,      0, 0x2000 }
    };

RE: PWM drive: how to generate PWM signals that are phase shifted 90 degree

Hakon — Thu, 14 Feb 2019 13:22:54 GMT

Hello, you should look at the pwm driver example. In the demo5 function there are four channels that are shifted 90 degrees to each other. This can be seen in the seq_values[] matrix.