Ok so each time we get guests over we have to explain how the head works. That the hose through which “All” flushes is quite small, so don’t use a lot of paper each time, or flush a few times. But we also have to explain, fill and flush by pushing buttons. So I set out to make a one button action.

We have a fill pump and an evacuate pump. so the easiest is to program an Arduino driving 2 relais, turning the pumps on and off.

First off the Arduino runs on 5V, so we need a stepdown DC-DC converter, 24-12 -> 5V. Luckily I had one laying around, otherwise I would have used a USB converter, like we have everywhere in the barge.

Then we needed a 2 relais board.

Each will control one Pump. You have the connections Gnd, Vcc ( 5V) and digital 1 and digital 2

And here we have the arduino.

The wiring was quite simple, we made digital 3 and 5 the control wires for the relais, we connected the 5V and the Ground on the Arduino to the Vcc and the Ground on the relais board, then we used digital 7 with a Ground for the button.

So when the button is momentary pressed, the Arduino opens Relais 1 ( flush pump) and let it run for a bit.
Then the Arduino opens Relais 2 ( fill pump) and let both pumps run for a bit.
Then the Arduino closes Relais 1 ( flush pump) while keeping Realis 2 open ( fill pump).
Then the Arduino closes Relais 2 ( fill pump).

I assembled all in a little sealed plastic bock and hooked it up, played with the times for each pump and got it working. A note to the ‘purist’ under the Arduino coders, YES pressing a momentary switch can cause several pulses, but the code only needs one and it runs for a few seconds until it looks to the button again, so why bother.

The button Deb selected to control the head 🙂

Here is the code which I uploaded to the Arduino.

const int BUTTON_PIN = 7; // Arduino pin connected to button’s pin
const int RELAY_PIN = 3; // Arduino pin connected to relay’s pin
const int RELAY_PIN2 = 5; // Arduino pin connected to relay’s pin

void setup() {
Serial.begin(9600); // initialize serial
pinMode(BUTTON_PIN, INPUT_PULLUP); // set arduino pin to input pull-up mode
pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode
pinMode(RELAY_PIN2, OUTPUT); // set arduino pin to output mode
}

void loop() {
int buttonState = digitalRead(BUTTON_PIN); // read new state

if (buttonState == LOW) {
//Serial.println(“The button is being pressed”);
digitalWrite(RELAY_PIN, HIGH); // turn on flush
delay(1500);
digitalWrite(RELAY_PIN2, HIGH); // turn on fill Both are on for 3 seconds
delay(3000);
digitalWrite(RELAY_PIN, LOW); // turn off flush
delay(5000);
digitalWrite(RELAY_PIN2, LOW); // turn off fill
}
else
if (buttonState == HIGH) {
// Serial.println(“The button is unpressed”);
digitalWrite(RELAY_PIN, LOW); // turn off
digitalWrite(RELAY_PIN2, LOW); // turn off
}
}

Now for the ones who do not want to play with an Arduino, or feel it is to complicated, the same can also be achieved ( for about the same price) with 2 time relais ( din mount)
One turns on the flush pump for an interval, the other relais waits a bit and then turns on, here is one who is 220V