DDR (Double Data Rate) extension device, control method, device and medium

The invention discloses a DDR expansion device, a control method, a control device and a medium, relates to the field of DDRs, and aims to increase the number of mounted DDR particles under the condition of keeping a signal line of a DDR controller unchanged, according to the DDR expansion device provided by the invention, when a chip selection signal end CS of the DDR controller is at a high level, the chip selection signal ends CS of a first DDR particle and a second DDR particle are at the high level, and the chip selection signal ends CS of the first DDR particle and the second DDR particle are at the high level. When the chip selection signal end CS of the DDR controller is at a low level, the chip selection signal end CS passing through the phase inverter, the third DDR particle and the fourth DDR particle is at a high level, and the number of the mounted DDR particles is increased by changing the action mode of the BANK GROUP address selection signal end BG and the chip selection signal end CS between