// g11. Mesure et transmission des valeurs analogiques présentes sur A0 à An au format JSON
// mmsgtablejson : tableau contenant un objet JSON
void lectureAll() {
  String msgjson = "[{\"val0\":";
  msgjson += val0;
  msgjson += ",";
  msgjson += "\"val1\":";
  msgjson += val1;
  msgjson += ",";
  msgjson += "\"val2\":";
  msgjson += val2;
  msgjson += ",";
  msgjson += "\"val3\":";
  msgjson += val3;
  msgjson += ",";
  msgjson += "\"val4\":";
  msgjson += val4;
  msgjson += "}]";
  server.sendHeader(F("Cache-Control"), F("no-cache, no-store, must-revalidate"));
  server.send(200, F("application/json; charset=utf-8"), msgjson);
}