RE: nRF24LE1 PWM frequency setting

Kevin — Mon, 27 May 2019 09:13:50 GMT

Hi Hakon,

Very appreciate your answer, that solved my confusion for few days !

please kindly update this in next version PS Doc, and another errata in my previous post, thanks.

Best Regards,
Kevin.

RE: nRF24LE1 PWM frequency setting

Håkon Alseth — Mon, 27 May 2019 07:51:58 GMT

Hi,

[quote user=""]First, may i know what the pre-scale value we chose to get the 4 kHz and 254kHz?[/quote]

4kHz: PWMCON (7:6) = 0b'11, and PWMCON[5:2] = 15

This gives 16M clk * 1 / (255 * (15+1) = ~4 kHz (generating an effective 2kHz pulse)

254 kHz: 4kHz: PWMCON (7:6) = 0b'00, and PWMCON[5:2] = 0

16M * 1 / (31 * (0 + 1) = ~516 kHz (generating an effective ~258 kHz pulse)

Quick test in firmware:

    // Fast
    #if 1
    PWMCON = 0x03;
    PWMDC0 = 15;
    // Slow
    #else
    PWMCON = 0xff;
    PWMDC0 = 127;
    #endif

So, the documentation is incorrect, as the PWM peripheral itself will be between 4 kHz and 516 kHz, with an effective output frequency of between 2 kHz and 258 kHz.

[quote user=""][/quote]

second, what is the available value for PWMCON bit5-2: PWM frequency pre-scale factor , is it from 0~15 ? all the 16 values can be chose ?

As per the first picture you attached, you can set the prescaler from 0 to 15. You are free to choose any value between.

Kind regards,

Håkon