Motor drivers
The motor drivers (L298N) use standard mosfet-based H-bridges to control the voltage polarity at its output connectors. The servo hat controls the motors drivers via 5V TTL lines and can modulate these using Pulse Width Modulation (PWM). For our purposes, this gives us the ability to precisely control our pumps and valve voltage.
Overall, connecting the different components is easy: one motor driver can be connected to two output devices, and each motor driver can be controlled by the servo hat board, for a theoretical maximum of 8 pumps or valves. Each motor driver is connected to a shared DC 12V 10 A power supply, with a 1000uF capacitor in parallel for each driver.
Exact details on how one motor is connected are described in the following figure:
In the main diagram you can find all the specific connections needed. To summarise:
- One motor driver for the safety pump and air pump
- One motor driver for the solenoid valve and the water-in pump
- One motor driver to water out 1 and water out 2 pumps (the pump distributing the mix of food and water to the tanks)
Reminder -- ZAF is modular and extra motor drivers can be added to accommodate additional pumps!