File content as of revision 1:db2a55107c7e:

#include "mbed.h"
#include <stdio.h>

Serial pc(USBTX, USBRX);

int main()
{
    uint32_t baud;
    uint32_t count;
    uint32_t index;
    uint32_t val;
    uint8_t str[64];

    count = 0;
    index = 0;

    pc.baud(115200);
    pc.printf("{init}");
    while(1) {
        while (1) {
            val = pc.getc();

            // Check for overflow. Leave space for
            // a null terminating character
            if (index >= sizeof(str) - 1) {
                index = 0;
            }

            // Check for start of frame
            if ('{' == val) {
                index = 0;
            }

            // Check for end of frame
            str[index] = val;
            index++;

            // Check for end of frame
            if ('}' == val && index > 0) {
                str[index] = 0;
                count = sscanf((char*)str, "{baud:%i}", &baud);
            }

            // Echo back character
            pc.putc(val);

            // Set baud if there is a valid command
            if (count == 1) {
                wait(0.01f);
                pc.baud(baud);
                wait(0.01f);
                pc.printf("{change}");
                count = 0;
            }
        }
    }
}