事實上我只想做單純傳送接收，當下達C1TX0CONbits.TXREQ = 1;命令之後，C1INTF=0x05a0，我查C1INTF暫存器發現分別是TXWAR,EWARN,IVRIF及ERRIF旗標動作了，而且之後我再下達C1TX0CONbits.TXREQ = 1;就沒有作用了，請問這是怎麼回事?以下是有關CAN1的設定

#define FCY 40000000 //40MHz
#define BITRATE 1000000 // 1Mbps
#define NTQ 20 // Number of Tq cycles which will make the
//CAN Bit Timing .
#define BRP_VAL ((FCY/(2*NTQ*BITRATE))-1)

C1CTRLbits.CANCKS = 1;
C1CFG1bits.SJW=00;
C1CFG1bits.BRP = BRP_VAL;
C1CFG2 = 0x06F4;
C1INTF = 0;
IFS1bits.C1IF = 0;
C1INTE = 0x00FF;
IEC1bits.C1IE = 1;

C1RX0CON = C1RX1CON = 0x0000;
C1RXM0SID = C1RXM1SID = 0x1FFD;
C1RXM0EIDH = C1RXM1EIDH = 0x0FFF;
C1RXM0EIDL = C1RXM1EIDL = 0xFC00;
C1RXF0SID = 0x0AA8;
C1TX0CON = 0x0003;
C1TX0SID = 0x50A8;
C1TX0DLC = 0x01C0;
out_c1tx0b1=1023;
out_c1tx0b2=1034;
out_c1tx0b3=1045;
out_c1tx0b4=1056;
C1TX0B1 = out_c1tx0b1;//1023;//OutData0[0];
C1TX0B2 = out_c1tx0b2;//1034;//OutData0[1];
C1TX0B3 = out_c1tx0b3;//1045;//OutData0[2];
C1TX0B4 = out_c1tx0b4;//1056;//OutData0[3];
C1CTRLbits.REQOP = 0;