Si5351Aクロックジェネレータ(90度位相シフト）

JH7UBCサイト［Si5351Aの実験その５（位相制御）］を使い９０度位相が違う２つのクロックを発生するテストを行いました。［frequency］に周波数を設定するとCLK0・CLK1から設定周波数が出力しCLK0・CLK1は90度位相がシフトします。【http://jh7ubc.1web.fc2.com/arduino/Si5351A_Phase.html】

●秋月電子通商　Si5351 レジスターマップ：【chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://akizukidenshi.com/goodsaffix/an619.pdf】

●位相レジスタ

　N = CLKx_PHOFF [6:0] = ROUND(DesiredOffset (sec) x 4 x  fvco)

　レジスタ165【CLK0】166【CLK1)】167【CLK2】

　■N = dt * 4 *  fvco --- (１)　（Nは0～127 ）

        dt = DesiredOffset（delay time）

        fvco = PLL周波数

　■dt = 1 / (4 * fout) --- (2)     (90度位相差)

        fout = 出力周波数

        dt = T / 4 = 1 / (4 * fout)　（T = 周期)

　(1) (2) の式を代入

　N = 1 / (4 * fout) * 4 *  fvco（Nは0～127 ）

   　= fvco / fout

　■N = divider = fvco / fout

回路図

CLK0(CH1) CLK1(CH2) 7MHz

7MHzはCLK0が遅れます

CLK0(CH1) CLK1(CH2) 10MHz

CLK0(CH1) CLK1(CH2) 50MHz

CLK0(CH1) CLK1(CH2) 100MHz

プログラム　Arduino IDE【ボード：Raspberry Pi　Pico】

#include <Wire.h>

#define Si5351A_ADDR 0x60

#define OUTPUT_CTRL 3 //Output Enable Control

#define CLK0_CTRL 16  //CLK0 Control

#define CLK1_CTRL 17  //CLK1 Control

#define CLK2_CTRL 18  //CLK2 Control

#define MSNA_ADDR 26  //Multisynth NA Parameters

#define MSNB_ADDR 34  //Multisynth NB Parameters

#define MS0_ADDR 42   //Multisynth0 Parameters

#define MS1_ADDR 50   //Multisynth1 Parameters

#define MS2_ADDR 58   //Multisynth2 Parameters

#define CLK0_PHOFF 165  //CLK0 Initial Phase Offset

#define CLK1_PHOFF 166  //CLK1 Initial Phase Offset

#define PLL_RESET 177   //PLL Reset

#define XTAL_LOAD_C 183 //Crystal Internal Load Capacitance

uint32_t frequency;

const uint32_t XtalFreq = 25000000; //25MHz

uint32_t P1;

uint32_t P2;

uint32_t P3;

uint32_t PllFreq;

uint32_t l;

float f;

uint8_t mult;

uint32_t num;

uint32_t denom;

uint32_t divider;

char PLL;

uint8_t PLL_ADDR;

uint8_t MS_ADDR;

void setup(){

Wire.setSDA(12);  //SDA 

Wire.setSCL(13);  //SCL  

Wire.begin(); // Arduino is Master

Si5351_init(); //Si5351 initialize

//PLLAのセット 900MHz,CLK0=10MHz 

//N(divider) = fvco(PLLA) / fout(CLK0)

frequency = 10000000;

divider = 900000000 / frequency; //divider = fvco / fout

if (divider % 2) divider--;

PLL_Set('A',frequency,divider);

//CLK0の設定

Si5351_write(CLK0_CTRL,0x4C); //Reg16 Sorce PLLA

MS_Set(0,divider);

Si5351_write(CLK0_PHOFF,0);//CLK0 delay 0

//CLK1の設定

Si5351_write(CLK1_CTRL,0x4C); //Reg17 Sorce PLLA

MS_Set(1,divider);

Si5351_write(CLK1_PHOFF,divider);//Reg166 delay T/4 (90degree)

Si5351_write(PLL_RESET,0xA0); //Reg177 PLLA and PLLB

}

void loop(){

}

//Si5351のレジスタに１バイトデータを書き込む。

void Si5351_write(byte Reg , byte Data)

{

Wire.beginTransmission(Si5351A_ADDR);

Wire.write(Reg);

Wire.write(Data);

Wire.endTransmission();

}

//Si5351Aの初期化

void Si5351_init(){

Si5351_write(OUTPUT_CTRL,0xFF); //Reg3 Disable Output

Si5351_write(CLK0_CTRL,0x80); //Reg16 CLOCK0 Power down

Si5351_write(CLK1_CTRL,0x80); //Reg17 CLOCK1 Power down

Si5351_write(CLK2_CTRL,0x80); //Reg18 CLOCK2 Power down

Si5351_write(XTAL_LOAD_C,0x92); //Reg183 Crystal Load Capasitance=8pF

Si5351_write(PLL_RESET,0xA0); //Reg177 Reset PLLA and PLLB

Si5351_write(CLK0_CTRL,0x4F); //Reg16 CLOCK0 Power up

Si5351_write(CLK1_CTRL,0x4F); //Reg17 CLOCK0 Power up

// Si5351_write(CLK2_CTRL,0x4F); //Reg18 CLOCK0 Power up

Si5351_write(OUTPUT_CTRL,0xFC); //Reg3 Enable CLOCK0,CLOCK1

}

//PLLの設定

void PLL_Set(char Pll,uint32_t Freq,uint32_t Div){

PllFreq = Div * Freq; //fvco =d * fout

mult = PllFreq / XtalFreq; //整数部　mult = a = fvco / fxtal

l = PllFreq % XtalFreq; // L = fvco % fxtal

f = l;

f *= 1048575;

f /= XtalFreq;

num = f;

denom = 1048575;

P1 = (uint32_t)(128 * ((float)num /(float)denom)); //128*(b/c)

P1 = (uint32_t)(128 * (uint32_t)(mult) + P1 - 512); //128*a + (128*(b/c))-512 

P2 = (uint32_t)(128 * ((float)num / (float)denom)); //128*(b/c)

P2 = (uint32_t)(128 * num -denom * P2); //128*b–c*(128*(b/c))

P3=denom;

if (Pll == 'A')

{

PLL_ADDR = MSNA_ADDR;

}else

{

PLL_ADDR = MSNB_ADDR;

}

Parameter_write(PLL_ADDR,P1,P2,P3);

}

//MultiSynth（分周器）のセット

void MS_Set(uint8_t MS_No,uint32_t Div){

P1 = 128 * Div - 512;

P2 = 0;

P3 = 1;

switch(MS_No){

case 0:

MS_ADDR = MS0_ADDR;

break;

case 1:

MS_ADDR = MS1_ADDR;

break;

case 2:

MS_ADDR = MS2_ADDR;

break;

default:

MS_ADDR = MS0_ADDR;

}

Parameter_write(MS_ADDR,P1,P2,P3);

}

//レジスタにパラメータP1,P2,P3を書き込む。

void Parameter_write(uint8_t REG_ADDR,uint32_t Pa1,uint32_t Pa2,uint32_t Pa3)

{

Si5351_write(REG_ADDR + 0,(Pa3 & 0x0000FF00) >> 8);

Si5351_write(REG_ADDR + 1,(Pa3 & 0x000000FF));

Si5351_write(REG_ADDR + 2,(Pa1 & 0x00030000) >> 16);

Si5351_write(REG_ADDR + 3,(Pa1 & 0x0000FF00) >> 8);

Si5351_write(REG_ADDR + 4,(Pa1 & 0x000000FF));

Si5351_write(REG_ADDR + 5,((Pa3 & 0x000F0000) >> 12) | ((Pa2 & 0X000F0000) >> 16));

Si5351_write(REG_ADDR + 6,(Pa2 & 0x0000FF00) >> 8);

Si5351_write(REG_ADDR + 7,(Pa2 & 0x000000FF));

}