Why initializes the UART with high priority receive interrupt need to make RCSTA2bits.CREN = 0;

Question

#define InitUART( BRGVal, BRGHighVal )      {                       \
                        UARTTxD = UARTTxDInit;                  \
                        DirUARTTxD = DirOutput;                 \
                        DirUARTRxD = DirInput;                  \
                        SPBRG2 = BRGVal;                        \
                        TXSTA2bits.BRGH = BRGHighVal;           \
                        TXSTA2bits.SYNC = 0;                    \
                        TXSTA2bits.TX9 = 0;                     \
                        TXSTA2bits.TXEN = 1;                    \
                        RCSTA2bits.SPEN = 1;                    \
                        RCSTA2bits.RX9 = 0;                     \
                        IPR3bits.RC2IP = 1;                     \
                        IPR3bits.TX2IP = 0;                     \
                        PIE3bits.TX2IE = 0;                     \
                        PIE3bits.RC2IE = 1;                     \
                        RCSTA2bits.CREN = 0;                    \
                        }

For the last line, i do not understand why clear the RECEIVE ENABLE FLAG i use PIC18LF6722

http://read.pudn.com/downloads153/sourcecode/others/669717/uart.c__.htm: This site indicates setting the CREN flag to 0 clears errors. Then re-enable. — thomas.cloud, Jul 11 '14 at 04:15

score 0 · Answer 1 · answered Jul 14 '14 at 11:37

CREN is the Continuous Receive Enable Bit, which means that in a receive routine, in asynchronous mode, the receive buffer will always clears itself after it's full, allowing a continuous receive of UART characters. In synchronous mode, it's used for other purpose, which you may look at in your PIC'S datasheet.

Why initializes the UART with high priority receive interrupt need to make RCSTA2bits.CREN = 0;

1 Answers1