Charging and discharging control circuit and system, charging gun and charging pile

The invention discloses a charging and discharging control circuit and system, a charging gun and a charging pile. The charging and discharging control circuit comprises a charging and discharging identification circuit, a charging and discharging main control circuit, a resistance switching circuit and a resistance circuit. The charging and discharging identification circuit is used for connecting load equipment and acquiring a load signal; the resistance circuit is used for connecting load equipment to form a resistance loop; and the resistance switching circuit is connected with the charging and discharging identification circuit and is used for being arranged in the resistance loop and switching the resistance value of the resistance loop according to the load signal, so that the load equipment executes a charging action or a discharging action according to the resistance value of the resistance loop, thereby automatically realizing charging or discharging detection and improving the user experience. 本发明公