title: STM32F4xx CAN Filter Configuration
body: <p>I am writing in reference to the information in the reference manual (bxCAN).</p>
  
  <p>I am trying to understand how <code>CAN</code> filter configuration works and need your help to check whether I understand it correctly or not.</p>
  
  <p>Especially the configuration of the filter ID and the filter mask ID.</p>
  
  <p>After I take a look of the <code>stdPeriphLib</code> and the ref. manual, I think that in understand what happens but I´m not sure. </p>
  
  <p><strong>FilterIdHigh/Low:</strong></p>
  
  <p>Is FilterIdHigh/Low the comparative value for <code>CAN Controller</code> after the binary AND with the <code>FilterIdMask</code>?</p>
  
  <p>e.g:
      CAN Controller receives a message --> CAN_Rx_</p>
  
  <pre><code>CAN Controller makes a binary AND with the FilterIdMask --&gt; 
      CAN_Rx_ArbitrationField &amp; FilterIdMask = Result
  </code></pre>
  
  <p>The <code>CAN Controller</code> compares the Result with the FilterId.</p>
  
  <p>If there is a match <code>CAN Controller</code> puts the CAN_Rx_ message into the assigned FIFO otherwise it will discard the message.</p>
  
  <p>Isn´t it?  </p>
  
  <p>Thank´s in advantage.</p>