Sump Pump Controller

We made this control system to deal with someone's flooding basement. A sump pump had already been installed but the owner had to manually switch on the pump every time water came in. The control system automates the sump pump turning it into an unattended system.

The system consists of a controller unit, a.k.a. water level controller, and an acrylic tower equipped with adjustable water level probes. Three cables are used to interconnect the controller unit and the tower.

The tower carries a high-level water probe, a low-level water probe, and a common ground probe. When the water rises, these probes make contact with the water. The controller unit detects low-level and high-level and feeds this information into a state machine. This state machine ultimately decides when the sump pump is switched on and off.

Sump Pump Controller State Machine

The system enters the low state after reset. At this point the sump pump is turned off. When the water has rises above the low-level probe and the high-level probe, the system enters the high state and switches on the sump pump. When the water drops below the low-level probe, the post state is activated. During this state, the system drives the sump pump for an additional amount of time before turning off the pump and then returns to the low state.

When the system transitions from high to post state, it samples the setting of the trim potentiometer to determine the amount of additional time.

The error state is activated when the high-level probe make contact while the low-level probe remains open.

The controller unit is powered through a standard 230 V AC inlet. The power on the inlet is routed to the outlet through a relay. The actual sump pump must be connected to the power outlet.

Sump Pump Test Setup

We successfully ran a very realistic kitchen-based simulation of a modestly flooded basement as shown in the image. Nowadays, the pump system is dutifully sucking dry a basement.

Design Files

The firmware was developed using WinAVR-20100110.

Sump Pump Controller Unit