Aerosol-generating device and system

An electrical system comprising a primary device and a secondary device, the primary device comprising:

• a source of electrical power;
• a cavity configured to receive the secondary device;
• at least one electrical contact within the cavity configured to contact a corresponding contact on the secondary device when the secondary device is in the cavity, the at least one electrical contact being electrically connected to the source of electrical power;
• at least one data contact configured to transfer data between the primary device and the secondary device;
• and
• a lid moveable between a first position to retain the secondary device in contact with the at least one electrical contact and the at least one data contact and a second position in which the secondary device is free to move out of contact with the at least one electrical contact and the at least one data contact, wherein in the first position the lid urges the secondary device into contact with the at least one electrical contact and the at least one data contact, and
• wherein the secondary device is keyed to the cavity of the primary device.