PWM with certain frequency

[Constantin]

Hi,

I need to generate a PWM signal with exact 2.048 MHz. I've just realized that 

typedef enum
{
    NRF_PWM_CLK_16MHz  = PWM_PRESCALER_PRESCALER_DIV_1,  ///< 16 MHz / 1 = 16 MHz.
    NRF_PWM_CLK_8MHz   = PWM_PRESCALER_PRESCALER_DIV_2,  ///< 16 MHz / 2 = 8 MHz.
    NRF_PWM_CLK_4MHz   = PWM_PRESCALER_PRESCALER_DIV_4,  ///< 16 MHz / 4 = 4 MHz.
    NRF_PWM_CLK_2MHz   = PWM_PRESCALER_PRESCALER_DIV_8,  ///< 16 MHz / 8 = 2 MHz.
    NRF_PWM_CLK_1MHz   = PWM_PRESCALER_PRESCALER_DIV_16, ///< 16 MHz / 16 = 1 MHz.
    NRF_PWM_CLK_500kHz = PWM_PRESCALER_PRESCALER_DIV_32, ///< 16 MHz / 32 = 500 kHz.
    NRF_PWM_CLK_250kHz = PWM_PRESCALER_PRESCALER_DIV_64, ///< 16 MHz / 64 = 250 kHz.
    NRF_PWM_CLK_125kHz = PWM_PRESCALER_PRESCALER_DIV_128 ///< 16 MHz / 128 = 125 kHz.
} nrf_pwm_clk_t;

allows only decimal frequency. Even if I take 16 MHz and toggle it every 7,8,9 still the closest is 2 MHz.

Is there a different way achieve higher accuracy using a Timer etc.

Thanks in advance.

C.W.

[Jared]

Hi,

Unfortunately, 2.048 MHz. is not possible as the PWM frequency = base_clock/top value where both base_clock and top value are whole numbers. The PWM library which use Timer, PPI and GPIOTE has a limitation at 200 kHz.

Regards

Jared