Error handling in serial communication

[edha]

I use 19200bps baudrate to send data from rcm5600w microcontroller to picasso display 4.3". Before I sending data from rabbit to picasso, I try to send data from the rabbit to the serial port of the computer and I look the data in hyperterminal, all goes according to expectations.

when I replace the computer with picasso, the data appeared in realtime, but after a moment data seemed to freeze. I am sure the error occurred in serial communication of picasso. Is the correct way to handle serial communication error in picasso like this? Thanks.

if((com1_Full() & (com1_Count()==0)) || com1_Error())
    com1_Init(packetIn, SERIN_BUFFER, 0);
endif

Completed Code:

// constant
#CONST
TOUCH_HANDSHAKING 0x40

MASTER_ID 0xFF
SLAVE_ID 0x01
STX 0x02
ETX 0x03
ACK 0x06
NAK 0x15

BAUDRATE 1920 // DON'T CHANGE
SERIN_BUFFER 255 // DON'T CHANGE
RX_TMOUT 100
#END

// member variable
var packetIn[SERIN_BUFFER];

// function
func reqHandshaking()
    var BCC, dt, n, pSTX, tmOut;

    // request handshake to rabbit
    serout1(STX);               BCC := 0;
    serout1(MASTER_ID);         BCC ^= MASTER_ID;
    serout1(TOUCH_HANDSHAKING); BCC ^= TOUCH_HANDSHAKING;
    serout1(ETX);               BCC ^= ETX;
    serout1(BCC);

    // read response of rabbit
    mem_Set(packetIn, NULL, sizeof(packetIn));
    n    :=  0;
    pSTX :=  -1;
    tmOut:= RX_TMOUT;
    while(tmOut--)
        if((com1_Full() & (com1_Count()==0)) || com1_Error())
            com1_Init(packetIn, SERIN_BUFFER, 0);
        endif
        if((dt := serin1())>=0)
            packetIn[n] := dt&0xFF;
            if(n==0 && packetIn[0]==STX)
                tmOut:= RX_TMOUT;
                pSTX := 0;
                BCC  := 0;
                n++;
                continue;
            else if(n>0 && pSTX==0)
                tmOut:= RX_TMOUT;
                if(n==6 && packetIn[n-1]==ETX)
                    if(packetIn[n]==BCC)
                        if(packetIn[1]==SLAVE_ID)
                            if(packetIn[2]==TOUCH_HANDSHAKING)
                                return (packetIn[3]<<4 + packetIn[4]);
                            endif
                        endif
                    endif
                endif
                BCC ^= packetIn[n];
                n++;
            endif
        endif
        if(n>sizeof(packetIn)-1) break;
    wend
    return -1;
endfunc

[ESPsupport]

Hmm, well (com1_Full() & (com1_Count()==0)) can never be true, as, when com1_Full() is true, com1_Count will be SERIN_BUFFER.

Anyway 'com1_Full()' and 'com1_Count()==SERIN_BUFFER' are effectively the same thing.

I also wonder if you meant '&&' rather than '&' although the effect here will be the same.

So maybe just fixing the above will fix your code, but that depends on what else is going on.

Note that com1_Init(packetIn, SERIN_BUFFER, 0); could actually be com1_Init(packetIn, SERIN_BUFFER*2, 0); due to the word architecture of Picaso

[edha]

Thanks for quick reply. I think & is a bitwise operator when applies to integer operands and so short-circuit when applies to bool operands, But && is a logical operator that applies to bool operands. Its right?

Still freeze, the data appeared in realtime but after a moment data seemed to freeze. Is there any other way to read the serial data using an interrupt, not a poll?

[ESPsupport]

Yes, correct, I would have just done it the other way around in this case, but obviously that's just personal preference, I guess.

I normally have a large comms buffer and 'poll' com_count() for being >= the required amount of data... Then you don't need to check for serin() being >= 0.

If you can't work it out, perhaps by adding a few strategic 'prints', post some code that I can 'just run' and information about what I need to send to see the issue

[edha]

Yes you are correct, I changed the code to be like this and my problem solved. Thanks .

    while(tmOut--)

        // serial error handle
        if(com1_Full() || com1_Count()==SERIN_BUFFER || com1_Error())
            com1_Init(packetIn, SERIN_BUFFER, 0);
            break;
        endif

        // is data ready in buffer?
        if(com1_Count()>0)

            // read data from buffer
            dt := serin1();

            // is valid data?
            if(dt>=0 && dt<=0xFF)
                // process valid data in here
            endif

        endif
    wend