testing with raspberry pi 3 about dma_pwm HOT 2 CLOSED

Hi tahanjokunimi,

Thanks for checking out dma_pwm and leaving a question.

The behavior that you describe in the first bullet point indicates an incorrectly set pulse width. I'm guessing that you did not update the config_pwm(int pages, float pulse_width) function call (found at the beginning of the test script) when changing the frequency to 100 Hz.

The test script sets pulse width to LED_PULSE_WIDTH. This maps to 10e3 us (or 10 ms) and is suitable for the frequency range 0.05 Hz - 10 Hz. If you would like to set a frequency outside this range, you can either calculate a pulse width or use one of the following presets:

1. DEFAULT_PULSE_WIDTH : 100 Hz - 20 kHz
2. SERVO_PULSE_WIDTH : 50 Hz - 10 kHz
3. MOTOR_PULSE_WIDTH : 5 kHz - 1 Mhz
4. LED_PULSE_WIDTH : 0.05 Hz - 10 Hz

See raspberry_pi_dma_pwm.pdf page 5 & 6 and "dma_pwm_pulse_width_calculator.xlsx" for a discussion on how to calculate this for yourself.

The behavior described in the second bullet point is something I'm going to look into further so let me get back to you on that.

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Hi tahanjokunimi,

I have just pushed a fix for the frequency issue that you discovered. Thank you for bringing it to my attention!

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