Oleg Evsegneev / SerialFlow

SerialFlow allows to send and receive packaged arrays of integer values via serial port.

SerialFlow allows to send and receive packaged arrays of integer(short only) values via serial port.

Packet format:

  1. begin - 0x12
  2. end - 0x13
  3. value separator - 0x10
  4. escape - 0x7D

Simple packet example:
0x12,0x1,0x0,0x10,0x7D,0x12,0x0,0x13
corresponds to: [1,18]

Now handles only short int values. Example:

#include "mbed.h"
#include "SerialFlow.h"
SerialFlow pc(USBTX, USBRX);
AnalogIn gyro_x(p17); // data from gyro x axis
AnalogIn gyro_y(p18); // data from gyro y axis

int main(){
    // two short values
    pc.setPacketFormat(SerialFlow::COMPLEX_1, 2, 2);
    while(1){
        pc.setPacketValue((short)(gyro_x*1023.0));
        pc.setPacketValue((short)(gyro_y*1023.0));
        pc.sendPacket();
        wait(0.01);
    }
}

On the PC side you can use this program to catch data flows: http://www.poprobot.ru/files/sfmonitor_0.9.zip

SerialFlow.cpp

Committer:
Decimus
Date:
2012-10-21
Revision:
4:ebf658b28c5f
Parent:
3:7cbfd422c98e

File content as of revision 4:ebf658b28c5f:

/* mbed Serial Flow Library
 * Copyright (c) 2012 Oleg Evsegneev
 * Released under the MIT License: http://mbed.org/license/mit
 */
 
#include "SerialFlow.h"
#include "mbed.h"

#ifdef USE_MODSERIAL
SerialFlow::SerialFlow(PinName tx, PinName rx): _serial(tx, rx, TX_BUFFER_SIZE, RX_BUFFER_SIZE) {
#else
SerialFlow::SerialFlow(PinName tx, PinName rx): _serial(tx, rx) {
#endif
    _escape = 0;
    _collecting = 0;
}

void SerialFlow::baud(int baud_rate) {
    _serial.baud(baud_rate);
}

void SerialFlow::setPacketFormat(DataFormat p_format, char v_length, char p_size) {
    _p_format = p_format;
    _v_length = v_length;
    _p_size = p_size;
    _vs_idx = 0;
    _vr_idx = 0;
}

void SerialFlow::setPacketValue(short value) {
    if( _vs_idx < _p_size ){
        _vs[_vs_idx++] = value;
    }
}

bool SerialFlow::sendPacket() {
    char v;
    if( !_serial.writeable() ){
        _vs_idx = 0;
        return 0;
    }
        
    _serial.putc( 0x12 );
    for( char i=0; i<_vs_idx; i++ ){
        // low byte
        v = _vs[i] & 0xFF;
        if( v==0x12 || v==0x13 || v==0x7D || v==0x10 )
            _serial.putc( 0x7D );
        _serial.putc( v );

        // high byte
        v = (_vs[i]>>8) & 0xFF;
        if( v==0x12 || v==0x13 || v==0x7D || v==0x10 )
            _serial.putc( 0x7D );
        _serial.putc( v );
            
        // separate values
        if( i<_vs_idx-1 )
            _serial.putc(0x10);
    }
        
    _serial.putc( 0x13 );
    _vs_idx = 0;
    return 1;
}

bool SerialFlow::receivePacket() {
    char c;
    while( _serial.readable() ){
        c = _serial.getc();
        if( _collecting )
            if( _escape ){
                _vr_val[_cr_idx++] = c;
                _escape = 0;
            }
            // escape
            else if( c == 0x7D ){
                _escape = 1;
            }
            // value separator
            else if( c == 0x10 ){
                _vr[_vr_idx++] = _vr_val[0] | (_vr_val[1] << 8);
                _cr_idx = 0;
            }    
            // end
            else if( c == 0x13 ){
                _vr[_vr_idx++] = _vr_val[0] | (_vr_val[1] << 8);
                _collecting = 0;
                return 1;
            }    
            else{
                _vr_val[_cr_idx++] = c;
            }    
        // begin
        else if( c == 0x12 ){
            _collecting = 1;
            _cr_idx = 0;
            _vr_idx = 0;
        }    
    }
    return 0;
}

short SerialFlow::getPacket( char idx ) {
    return _vr[idx];
}