XON / XOFF uart flow control

[fdaniii]

Hi everybody,

I'm working with a project that needs to transfer higth speed serial data from a XMOS device to a HOST PC.

I used the modules fast uart (https://github.com/xcore/sc_uart) prensent in gihub repository.

I want to implement a serial XON/XOFF software flow control to transfer data from XMOS device to a host PC.

I wrote the following code, but seems doesn't work well.


//Send buffer data to UART
void SendToSerial(streaming chanend DataFromFIFO, streaming chanend DataFromHostPC, streaming chanend DataToHostPC) {
    unsigned int     rx;
    unsigned char  XON = 1;
    unsigned char     RxFlow;    
    
    while(1){
        select {
        // xon/xoff char received from PC
        case DataFromHostPC:> RxFlow:

            if ( RxFlow == XOFF_CHAR){
                XON = 0;
            }
            if ( RxFlow == XON_CHAR ){
                XON = 1;

            }
            break;
            
        // data from fifo to be sent over uart to the host pc
        case DataFromFIFO :> rx:

                // Checking if the transmission must be stopped
                while( XON == 0 ){
                    DataFromHostPC:>RxFlow; // wait PC command

                    if ( RxFlow == XON_CHAR ){
                        XON = 1;
                    }

                }        // wating xon char ok

                DataToHostPC <: rx;
                break;


        }
    }

}

In main, i have:

    par {
        GetFromFIFO(DataFromFIFO);                                        //  Get data from fifo
        HandleUart(DataFromFIFO,DataFromHostPC,DataToHostPC);            //     Send data to UART
        ReceiveXOFF(DataFromHostPC);                                    // Get data received from PC via UART
        SendToHost(DataToHostPC);                                        //     Send data to UART
    }

 

Checking the serial lines with the oscilloscope, when the XOFF char is sent by the host pc, the data doesn't stops. Where is the problem?

How to proper implement xon/xoff software flow control? Is there any sample code?

Thanks in advance.

 

 

 
 

[sethu_jangala]

Moved to Discussion:http://www.xcore.com/forum/viewtopic.php?f=26&t=2552