I am using the simulator of the uvision2. According to the debugger the value of c doesn't change (I am using the serial peripheral) and the debugger never execute the Start_bit = 1; even though the SBUF = 0x46.
char c ; void SerialPort(void) interrupt 4 using 2 { if (RI == 1) { c = SBUF; if(SBUF==0x46) Start_bit = 1; RI = 0; } }
The SCON = 0x50; IE = 1; Thank you very much for your help
IE = 1 guarantees that you will not get any interrupts. Have a look at <a href="" target="_blank">http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_PROG_GUIDE_1.pdf">the proframmers reference manual</a> and set the SFRs ciorrectly. Erik
Hi I finnaly understood that the local variable is changed to zero and didn't stay at zero (which means that it doesn't succcefuly read the SBUF???). here are all my init values.
TMOD = 0x20; TH1 = 0xFB; // baud ~19200; TR1 = 1; SCON = 0x50; IE=0x90; EA = 1; ES = 1; REN = 1; RI = 0; void SerialPort(void) interrupt 4 using 2 { while(!RI) { if(ArrLenFlag==0) { ArrLen = _getkey (); ArrLenFlag = 1; } else { if(_getkey()=='S') { Start_bit = 1; SaveData(1000); SaveData(1000); } else { chr = _getkey (); SaveData(chr); } } RI = 0; TI = 0; } }