PicForum

hello every body .
how can i configure the stop bits,parity and flow control in c18 for uart?

There are no such things implemented in hardware.
I think you have to implement them by yourself in software.
What you need it for ?

In fact,i didn't see any thing about them in OpenUSART of c18 compiler or in registers.
i want to connect with sim900.i can get connected to my computer properly and send and receive command.but with micro controller it seems impossible
i can send command but the uart can't receive proper data.it gets the first two character of my sent command.for example if i send ATE0 in RX i get AT although i get OK in RX of my computer(i connect RX of micro and computer simultaneously )!!

What is the BAUDRATE and clk frequency of your pic ?
Do you use interrupt for the receiver ?

oops there is another thing ,i think that it's because of overrun error ,because it's bit is set,what should i do after clearing CREN as the datasheet said?i did this:
if(RCSTAbits.OERR==1){RCSTAbits.CREN=0;Delay10KTCYx(50);RCSTAbits.CREN=1;}
but i got the same result.

vloki wrote:What is the BAUDRATE and clk frequency of your pic ?
Do you use interrupt for the receiver ?

BAUDRATE=9600 and clk frequency=8 MHZ
nope,this is the main part of my code:

Code: Select all

putrsUSART("AT\r");Delay10KTCYx(200);
putrsUSART("ATD09133957792;\r");Delay10KTCYx(200);
   while(1)
   {

    if(RCSTAbits.OERR==1){putrsXLCD("hi");RCSTAbits.CREN=0;Delay10KTCYx(50);RCSTAbits.CREN=1;}
    while (!DataRdyUSART());
    recieved_data=ReadUSART();
    putcXLCD(recieved_data);
 
   }


Overflow should never happen or your system wont work
Of course you need error handling anyway. Something like in this interrupt service routine:

Code: Select all

    if (IR_USART) // -------------------------------------------------- USART_IR
    {
        if (RCSTA1bits.OERR) // check overflow error
        {
            rxBuffer.bytes[0] = RCREG;  // clear the receiver fifo
            rxBuffer.bytes[0] = RCREG;
            rxBuffer.idx = 0;
            RCSTA1bits.CREN = 0;        // clear the OVR flag
            RCSTA1bits.CREN = 1;
//            PC_inPck.ID.all = ERRFLAG;  // send (prepare) error message
//            PC_inPck.Size = 2;
//            PC_inPck.Bytes[0] = SERR | SERR_OVR;
//            PC_inPck.Flags.CMDTODO = 1;
            return;
        }
        if (RCSTA1bits.FERR) // check framing error
        {
            rxBuffer.bytes[0] = RCREG;  // clear the receiver fifo
            rxBuffer.idx = 0;
//            PC_inPck.ID.all = ERRFLAG; // send (prepare) error message
//            PC_inPck.Size = 2;
//            PC_inPck.Bytes[0] = SERR | SERR_FRAME;
//            PC_inPck.Flags.CMDTODO = 1;
            return;
        }
        if (DataRdy1USART()){ //-------------------- new byte received ###
            if(rxBuffer.idx < MAX_RX_BUFFER){
                rxBuffer.bytes[rxBuffer.idx++] = RCREG;
            }
            else{
                status.rxOVF = 1;
            }
        }
        return;//IR_USART
    }

The IR only saves the received byte into a buffer and the main program processes it later like below
where RXbyteImport is a function that collects the incoming bytes into a package and checks for a complete message

Code: Select all

// new bytes from PC -----------------------------------------------------------
        if(rxBuffer.idx){           //###TODO### ERROR overflow !!!
            mDIS_IR_USART();
            RXbyteImport(rxBuffer.bytes[0]);
            rxBuffer.idx--;
       for(i=0;i<=rxBuffer.idx;i++){
      rxBuffer.bytes[i] = rxBuffer.bytes[i+1];
            }
            mEN_IR_USART();
//            status.rxOVF = 0;
        }

You want to do something like this http://www.open-electronics.org/mini-gs ... thout-gps/

You could change the above into:

Code: Select all

// new bytes from PC -----------------------------------------------------------
        if(rxBuffer.idx){           //###TODO### ERROR buffer overflow !!!
            mDIS_IR_USART();
            received_data = rxBuffer.bytes[0];
            rxBuffer.idx--;
            for(i=0;i<=rxBuffer.idx;i++){
                rxBuffer.bytes[i] = rxBuffer.bytes[i+1];
            }
            mEN_IR_USART();
            putcXLCD(recieved_data);
        }

thank you very much .
but there still questions doesn't the usart of c18 have a mechanism like this ?
what is rxBuffer.idx ?is it in c18 or another compiler or you define it?

You should view the data sheet for your PIC
and the compilers library documentation

rxBuffer is something I defined

Code: Select all

struct s_rxBuffer{                      // receiver buffer
    unsigned char idx;
    unsigned char bytes[MAX_RX_BUFFER];

...
struct s_rxBuffer    rxBuffer;       // vom PC empfangene Bytes
};

idx -> index (or a pointer to the next byte to write)