AudioPLLSetting.go

/*
i.MX RT1020のAudio PLLの最適設定を求めるコード
PLLFreq = ref * (div + ( num / denom ))
*/
package main

import (
	"fmt"
	"math"
)

/*
44.1kHz 22.5792MHz
div: 30
denom 625
num: 66
PLLFreq: 722.5344MHz(22.5792 * 32)
*/

/*
48kHz 24.576MHz
div: 32
denom: 125
num: 96
PLLFreq: 786.432MHz(24.576 * 32)
*/

func main() {
	const ref = 24.0          // リファレンスクロック(MHz)
	const dest = 24.576       // 目標の周波数(MHz)
	var diff float64 = 100.0  // 目標の周波数との差
	var PLLFreq float64 = 0.0 // PLLした周波数

	for div := 27; div <= 54; div++ {
		for denom := 0; denom <= 96000; denom++ {
			for num := 0; num < denom; num++ {
				PLLFreq = ref * (float64(div) + (float64(num) / float64(denom)))
				if diff > math.Mod(PLLFreq, dest) {
					diff = math.Mod(PLLFreq, dest)
					fmt.Printf("div: %v, denom: %v, num: %v, PLLFreq: %v, diff: %v\n", div, denom, num, PLLFreq, diff)
				}
			}
		}
	}
	fmt.Println("Finished")
}