Bobby,

Someone please correct me if I'm wrong, but if the pump does indeed require an AC sine wave you could still generate it with an 8051. Choose a part with a PCA and generate a PWM sine wave using a lookup table for the duty cycle of each pulse. If the PWM frequency is much higher than the line frequency, the inductance of the transformer will smooth out the output. Harmonics will tend to heat the motor, but I would imagine that effect is negligible in an application like this.

If this device is operating in a battleship with your CAN or RS485 guns (you posted about this previously, right?), why not make the pumps operate on the same network? That would be pretty slick.

In regards to your lost battleship, I would like to express my deepest regrets. It is truly a tragedy that so many brave sailors lost their lives because of a $9.95 bilge pump.

- Lee