I have some questions about PLL parameters.
First of all I refer to PLL scheme:
The output frequency is given by:
The questions are:
- Range of N? In reference manual is stated that “N = Multiplier is 9 bits and supported range is 1 to 511”, but in register description the field is 16 bits wide. I wonder if N is 9 or 16 bit wide.
I wonder how to set the N field once I want to multiply by a certain value. For example, take into account Audio PLL. Maybe the value of N is equal to AUDIO_N+1 where AUDIO_N is bits 31-16 of AUDIOPLL_CTRL register. For example if I want to multiply by 34, do I need to write 33 o 34 in AUDIO_N?
What happes if I write 0 in that field? It multiply by 1 or by 0? - Range of P? Same as above. Maybe the value of P is equal to AUDIO_P+1 where AUDIO_P is bits 15-8 of AUDIOPLL_CTRL register. If I want to divide by 3, do I need to write 2 or 3 in AUDIO_P field?
- Range of M? Same as above. Maybe the value of M is equal to AUD_MDIV2+1 where AUD_MDIV2 is bits 7-0 of AUDIOPLL_DIV2 register. If I want to divide by 3, do I need to write 2 or 3 in AUDIO_P field? In table 1-80 is listed supported divide ratios for M. What does it means? What happes if I write 23 in AUD_MDIV2?
- Range of FREQ? In reference manual is stated that “FREQ = Supported integer range is 8 to 15 and fraction range is 0 to FFFF FFFFh.”. I guess that the fractional part range is a typo, since it is 24 bit wide, so its range should be 0-00FF FFFFh. What happens if I set integer part to 3?
Thanks
Best regards
