       else
         Wl("--- S ---");
       switch(c) { // yes, code like this sucks
-        case 's': // serial number
+        case 'i': // serial number
           Wl("Request serial number.");
           sha204.wakeup(rx_buffer);
           r = sha204.serialNumber(rx_buffer);

          print_return_code(r);
          print_received_from_sha(rx_buffer);
          break;
        case 'k': // wake
          Wl("Test waking up.");
          print_executing();

void print_help(void) {
  Wl("*** SHA204 playground [(c) 2014 flabbergast] ***\n\r");
  Wl("Raw commands: wa[k]e [c]heckMAC [d]erive_key dev_re[v]ision [g]en_dig [h]MAC");
  Wl("              [m]ac [n]once [r]andom r[e]ad [w]rite [u]date_extra [s]ha");
  Wl("Processed commands: ser[i]al c[o]nfig_zone");
  Wl("Playground config: [I]dle-or-sleep");
  Wl("'?' -> this help");
  Wl("Dangerous/one-time only! [L]ock\n\r");
