File content as of revision 0:8f5379c94a69:

#include "xbee.h"

DigitalOut led_1(LED1);
Mail<vector<char>, 30> received_messages;
RawSerial xbee(p13, p14);
const int FRAME_SPECIFIC_DATA_BEGIN[14] = {0x10, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFE, 0x00, 0x00};
const int RECEIVE_PACKET_MESSAGE_START_INDEX = 15;

const char START_DELIMITER = 0x7E;

void send_message_via_xbee(const char* message, const int length)
{
    const vector<char> transmit_request = generate_transmit_request(message, length);
    
    for(int i=0; i<transmit_request.size(); i++)
    {
        xbee.putc(transmit_request[i]);
    }
}

vector<char> generate_transmit_request(const char* message, const int length)
{
    vector<char> request;
    
    unsigned char checksum = 0xFF;
    
    request.push_back(START_DELIMITER);
    
    const uint16_t frame_length = 0x0E + length;
    const uint8_t frame_length_msb = frame_length >> 8;
    const uint8_t frame_length_lsb = (frame_length << 8) >> 8;
    request.push_back(frame_length_msb);
    request.push_back(frame_length_lsb);
    
    for(int i=0; i<14; i++)
    {
        request.push_back(FRAME_SPECIFIC_DATA_BEGIN[i]);
        checksum -= FRAME_SPECIFIC_DATA_BEGIN[i];
    }
    
    for(int i=0; i<length; i++)
    {
        request.push_back(message[i]);
        checksum -= message[i];
    }
    
    request.push_back(checksum);
    
    return request;
}

void read_frame()
{
    while(true)
    {
        while(xbee.getc() != 0x7E);
        
        vector<char> frame;
        
        frame.push_back(0x7E);
        
        const uint8_t frame_size_msb = xbee.getc();
        const uint8_t frame_size_lsb = xbee.getc();
        frame.push_back(frame_size_msb);
        frame.push_back(frame_size_lsb);
        const uint16_t frame_size = (frame_size_msb << 8) + frame_size_lsb;
        
        for(int i=0; i<frame_size + 1; i++)
        {
            frame.push_back(xbee.getc());
        }
            
        vector<char> *parsed_frame = received_messages.alloc();
        *parsed_frame = parse_receive_packet(frame);

        received_messages.put(parsed_frame);
    }
}

vector<char> parse_receive_packet(vector<char> transmitted_request)
{    
    vector<char>::const_iterator first = transmitted_request.begin() + RECEIVE_PACKET_MESSAGE_START_INDEX;
    vector<char>::const_iterator last = transmitted_request.end() - 1;
    vector<char> message(first, last);
    return message;
}

void handle_message()
{
    while(true)
    {
        osEvent event = received_messages.get();
        if (event.status == osEventMail) 
        {
            vector<char> *message = (vector<char>*)event.value.p;
            
            printf("Received message: ");
            for(int i=0; i<message->size(); i++)
            {
                printf("%c", message->at(i));
            }
            printf("\r\n");
            received_messages.free(message);
        }
    }
}