34.16.2 Auto-Baud Overflow

During the course of automatic baud detection, the ABDOVF bit will be set if the baud rate counter overflows before the fifth falling edge is detected on the RX pin. The ABDOVF bit indicates that the counter has exceeded the maximum count that can fit in the 16 bits of the UxBRG register pair. After the ABDOVF bit has been set, the state machine continues to search until the fifth falling edge is detected on the RX pin. Upon detecting the fifth falling RX edge, the hardware will set the ABDIF Interrupt flag and clear the ABDEN bit. The UxBRG register values retain their previous value. The ABDIF flag and ABDOVF flag can be cleared by software directly. To generate an interrupt on an Auto-Baud Overflow condition, all the following bits must be set:
  • ABDOVE bit
  • UxEIE bit in the PIEx register
  • Global Interrupt Enable bits

To terminate the auto-baud process before the ABDIF flag is set, clear the ABDEN bit, then clear the ABDOVF bit.