I am back to working on my plant watering system.
Alas a new problem has happened and I am seriously thinking of rebuilding the entire circuit.
I have already bought 5v relays to use.
My project “needs”:
5 outputs to drive relays (then 12v solenoids).
1 (analogue) input sensor.
1 Button. (at least one.)
RTC (I2C), so that’s 2 pins.
A “display”. (Work in progress here.)
What I “have”:
I bought an 8 relay (5v) board. Future compatible. I am sure there are more functions needing to be added.
1 x 7 segment display. I am thinking of making it 2. That will only cost me 2 more pins, as I will run it BCD and there will be 2 pins for digit selection and digit blanking.
An input button.
Doing a pin count, this is how I see things:
BCD bus: 4 pins
Digit blank 1 pin / digit. 2 pins if 2 digits.
Digit select 1 pin / digit. 2 pins if 2 digits.
8 relays - well may as well go the whole hog.
I2C bus. 2 pins.
Button. 1 pin.
That’s 19 pins so far.
Ok, I could cut back on 3 pins for relays as I am only using 5 for now… But…
So that is 16 Pins at a pinch.
I was thinking of using a LCD instead of the 2 x 7 segment displays.
But I’m not sure if that would really gain me any more pins.
There seems to be more pins on the main picture than the 8 I need now with the two 7 segment displays.
Going to a MEGA seems… “Overkill” in that I would go from too few pins to… WAY TOO MANY. Kind of thing.
Another thought is to get one of those I2C I/O chips… They only cost a few dollars and I have used one before.
Anyone got any suggestions on pin usage and the best option to get the needs of the project, vs pins available, to work?