I/O assignments

I have the STM8S periodically pumping water to the duckweed tank to maintain circulation. I’ve added polyester fibre fill stuffing as a water filter. It looks like algae is making the water cloudy. While this is also a carbon dioxide sink, I think it will eventually kill the duckweed, as they compete for nutrients.

Here’s my preliminary list of I/O (inputs and outputs) for the microcontroller:

Water Pump. I found a $9 water pump with a USB connector, 5 Volt, 55 mA. Still too much current to drive directly from the STM8S so using a 2N3904 transistor to drive it.

LED lights. haven’t decided to go single LED or RGB. There are cool RGB ones for $2.57 that only need 5 volts and a data line input.

Air fan, battery voltage, solar panel voltage.

5 volt temperature transmitter. I’m amazed that the surface mount ones only cost 30 cents. Consider temperature transmitter probes for industrial use are $250 at the Omega website. The same low-cost is seen for gyros and accelerometers which are standard inside any smart phone. Humidity sensors which are not as common are $9.18 but I don’t expect there will be any in the final Carbon Block product.



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