title: CAN error counters and interrupts
body: <p>I'm using the bxCAN peripheral of an STMF3 uC in an environment where</p>
  
  <p>1.) it is essential that the node is detached from the network once the REC/TEC has reached the warning level (waiting for the bus-off condition is not an option)</p>
  
  <p>2.) the baud rate of the host network is unknown</p>
  
  <p>3.) the connection might be sporadic as the node is connected by the user</p>
  
  <p>Due to 1.) the STM32 HAL CAN driver is used in IT mode and whenever the called with the EWG flag set, the error callback shuts down the transceiver and deinitializes the bxCAN. In case the REC is over the limit, it is easily recovered by configuring the bxCAN in silent mode, assuming there is traffic on the CAN. However, if the TEC is over the limit, the bxCAN won't be able to transmit an other frame as the error interrupt will be instantly triggered once enabled -> there we are in a deadlock. </p>
  
  <p>I tried decrementing the TEC by transmitting frames in silent loopback mode but successful transmissions do not affect the TEC in this mode it seems.</p>
  
  <p>I suppose the question is not specific to this peripheral but valid for other CAN implementations.</p>
  
  <p>Any suggestions are welcome.</p>