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The Circuit
The Motherboard consists of a T-Cobbler, motor driver boards, 0.1 microfarad capacitors, and wires to make the connections. All these components will be soldered onto a prototyping board to make efficient use of space.
- T-Cobbler: an expansion for the GPIO of the Rasberry Pi.
- Motor driver: used to control the motor and handle back emf
- capacitors (0.1 uF): used to filter out AC components
Figure 1: On the left of the Motherboard is the T-Cobbler and on the right is the motor driver
The T-Cobbler is a 2x20 connector that we will use specific pins to send signals to the fans, humidity/temperature sensor, ultrasonic sensor, pump, servos, and lights. The specific pins connecting to these components will be specified in the table below:
| Humidity & Temperature sensor | |
|---|---|
| 5V | vcc |
| pin 4 | signal |
| gnd | gnd |
Table 1: Pin Connections for Humidity & Temperature Sensor
| Ultrasonic Sensor | |
|---|---|
| 5V | vcc |
| pin 23 | trig |
| pin 24 | echo |
| gnd | gnd |
Table 2: Pin Connections for Ultrasonic Sensor
| Servo | |
|---|---|
| 5V | vcc |
| pin 25 | signal |
| gnd | gnd |
Table 3: Pin Connections for Servo
| Pumps | |
|---|---|
| pin 6 | pump signal |
Table 4: Pin Connections for Pumps
| Lights | |
|---|---|
| pin 5 | light signal |
Table 5: Pin Connections for Lights
| Fans | |
|---|---|
| pin 26 | fan signal |
Table 6: Pin Connections for Fans
Figure 2: T-Cobbler soldered onto Prototyping Board
Figure 3: T-Cobbler Soldering Connections
The Motor driver board consists of 2 motor drivers, four 0.1 uF capacitors, and wiring connections.
| Wire | Connects to |
|---|---|
| Red | Power |
| Yellow | Signal |
| Black | Ground |
There are two motor drivers because one motor driver will control two fans while the other motor driver will control one pump.
Figure 3: Motor Driver Board
The logic of the motor driver is shown in the truth table below:
Figure 4: Motor Driver Truth
** NOTE:update which motor driver truth table is for the pump vs the 2 fans.