Si5351时钟芯片控制

Si5351

一、SI5351频率计算公式：

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     f(out) = f(pll) / M(x)R(x) 
    
   
 </span><span class="katex-html"><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10764em;">f</span><span class="mopen">(</span><span class="mord mathdefault">o</span><span class="mord mathdefault">u</span><span class="mord mathdefault">t</span><span class="mclose">)</span><span class="mspace" style="margin-right: 0.277778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right: 0.277778em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10764em;">f</span><span class="mopen">(</span><span class="mord mathdefault">p</span><span class="mord mathdefault" style="margin-right: 0.01968em;">l</span><span class="mord mathdefault" style="margin-right: 0.01968em;">l</span><span class="mclose">)</span><span class="mord">/</span><span class="mord mathdefault" style="margin-right: 0.10903em;">M</span><span class="mopen">(</span><span class="mord mathdefault">x</span><span class="mclose">)</span><span class="mord mathdefault" style="margin-right: 0.00773em;">R</span><span class="mopen">(</span><span class="mord mathdefault">x</span><span class="mclose">)</span></span></span></span></span></span></p> 

1、小于150Mhz

先设置PLL的频率

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     f(pll) = f(晶振频率)(a + b/c) 
    
   
 </span><span class="katex-html"><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10764em;">f</span><span class="mopen">(</span><span class="mord mathdefault">p</span><span class="mord mathdefault" style="margin-right: 0.01968em;">l</span><span class="mord mathdefault" style="margin-right: 0.01968em;">l</span><span class="mclose">)</span><span class="mspace" style="margin-right: 0.277778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right: 0.277778em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10764em;">f</span><span class="mopen">(</span><span class="mord cjk_fallback">晶</span><span class="mord cjk_fallback">振</span><span class="mord cjk_fallback">频</span><span class="mord cjk_fallback">率</span><span class="mclose">)</span><span class="mopen">(</span><span class="mord mathdefault">a</span><span class="mspace" style="margin-right: 0.222222em;"></span><span class="mbin">+</span><span class="mspace" style="margin-right: 0.222222em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault">b</span><span class="mord">/</span><span class="mord mathdefault">c</span><span class="mclose">)</span></span></span></span></span></span></p> 

a+b/c的范围 （15 + 0/1048575, 90)

a、b、c的设置方法参照文档设置MSNx_P1[17:0]、MSNx_P2[19:0]、MSNx_P3[19:0]寄存器
MSNA_P1[17:0]、MSNA_P2[19:0]、MSNA_P3[19:0]

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     MSNA_P1[17:0] = 128 *a+Floor(128* b/c) - 512 
    
   
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     MSNA_P2[19:0] = 128*b - c*Floor(128* b/c) 
    
   
 </span><span class="katex-html"><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10903em;">M</span><span class="mord mathdefault" style="margin-right: 0.05764em;">S</span><span class="mord mathdefault" style="margin-right: 0.10903em;">N</span><span class="mord"><span class="mord mathdefault">A</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height: 0.328331em;"><span class="" style="top: -2.55em; margin-left: 0em; margin-right: 0.05em;"><span class="pstrut" style="height: 2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathdefault mtight" style="margin-right: 0.13889em;">P</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height: 0.15em;"><span class=""></span></span></span></span></span></span><span class="mord">2</span><span class="mopen">[</span><span class="mord">1</span><span class="mord">9</span><span class="mspace" style="margin-right: 0.277778em;"></span><span class="mrel">:</span><span class="mspace" style="margin-right: 0.277778em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord">0</span><span class="mclose">]</span><span class="mspace" style="margin-right: 0.277778em;"></span><span class="mrel">=</span><span class="mspace" style="margin-right: 0.277778em;"></span></span><span class="base"><span class="strut" style="height: 0.64444em; vertical-align: 0em;"></span><span class="mord">1</span><span class="mord">2</span><span class="mord">8</span><span class="mspace" style="margin-right: 0.222222em;"></span><span class="mbin">∗</span><span class="mspace" style="margin-right: 0.222222em;"></span></span><span class="base"><span class="strut" style="height: 0.77777em; vertical-align: -0.08333em;"></span><span class="mord mathdefault">b</span><span class="mspace" style="margin-right: 0.222222em;"></span><span class="mbin">−</span><span class="mspace" style="margin-right: 0.222222em;"></span></span><span class="base"><span class="strut" style="height: 0.46528em; vertical-align: 0em;"></span><span class="mord mathdefault">c</span><span class="mspace" style="margin-right: 0.222222em;"></span><span class="mbin">∗</span><span class="mspace" style="margin-right: 0.222222em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.13889em;">F</span><span class="mord mathdefault" style="margin-right: 0.01968em;">l</span><span class="mord mathdefault">o</span><span class="mord mathdefault">o</span><span class="mord mathdefault" style="margin-right: 0.02778em;">r</span><span class="mopen">(</span><span class="mord">1</span><span class="mord">2</span><span class="mord">8</span><span class="mspace" style="margin-right: 0.222222em;"></span><span class="mbin">∗</span><span class="mspace" style="margin-right: 0.222222em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault">b</span><span class="mord">/</span><span class="mord mathdefault">c</span><span class="mclose">)</span></span></span></span></span></span></p> 

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     MSNA_P3[19:0] = c 
    
   
 </span><span class="katex-html"><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"></span><span class="mord mathdefault" style="margin-right: 0.10903em;">M</span><span class="mord mathdefault" style="margin-right: 0.05764em;">S</span><span class="mord mathdefault" style="margin-right: 0.10903em;">N</span><span class="mord"><span class="mord mathdefault">A</span><span class="msupsub"><span class="vlist-t vlist-t2"><span class="vlist-r"><span class="vlist" style="height: 0.328331em;"><span class="" style="top: -2.55em; margin-left: 0em; margin-right: 0.05em;"><span class="pstrut" style="height: 2.7em;"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mathdefault mtight" style="margin-right: 0.13889em;">P</span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span class="vlist" style="height: 0.15em;"><span class=""></span></span></span></span></span></span><span class="mord">3</span><span class="mopen">[</span><span class="mord">1</span><span class="mord">9</span><span class="mspace" style="margin-right: 0.277778em;"></span><span class="mrel">:</span><span class="mspace" style="margin-right: 0.277778em;"></span></span><span class="base"><span class="strut" style="height: 1em; vertical-align: -0.25em;"&