MegaShield

A fully customized 4-layers PCB for mechatronics DIY hobbyist that can support up to 24 servo motors, bluetooth/2.4GHz transceiver, gyroscope, and camera module. (Up to 7.5V/15A input)

It features

24 Servo motors
1x HC05/HC06 Bluetooth module
1x NRF24L01 radio receiver module
1x Camera module (e.g., OV7670)
3x GPIO interfaces
3x PWM analog read interfaces
2x 5V power ports (shared with the MCU)
2x 3.3V power ports (shared with the MCU)
2 independent power supply sockets (allowing the MCU and motors to be powered by two separate power sources, enhancing the stability of both the MCU and motor operations)
Sufficient capacitor placements to improve the stability of peripheral modules and motors
4-layer PCB design, consisting of (from top to bottom): Signal Layer 1, Vcc Layer, GND Layer, and Signal Layer 2. The power layer is designed with sufficiently wide and thick traces to support up to 15A of current input. The GND layer uses a multi-point grounding copper pour approach (with three large copper pour areas for the 24 motor grounds, input ground, and peripheral module grounds, connected by short and thick traces to minimize potential interference issues).

Assembly Guidance

To power 18 RDS3225 servo motors simultaneously while avoiding voltage drop issues, a large 0.6F capacitor was placed at C1, with a relatively smaller 1000µF capacitor placed in parallel at C2.

Capacitors of 100µF, 10µF, and 0.1µF were placed at C3, C4, and C5 respectively. A 1kΩ resistor was placed at R1 and a 2kΩ resistor at R2 to create a voltage divider circuit, which reduces the voltage to around 3.3V for the RX pin of the HC05/06 module. For more details, please refer to the shared Gerber file below.

https://drive.google.com/drive/folders/17j_bDiwszHmci_YNZK1wv7SDB-q9JGdj?usp=sharing

Pin Definition

Below are the shield pins corresponding to the pins on the Arduino Mega2560:

Pin	Correspond Arduino Pin	Description
HC05/HC06
EN	-	-
VCC	-	Main power supply (shared with servo motors)
GND	GND	-
TX	RX3	-
RX	TX3	-
STATE	-	-
Servo Motor Pins
S	PIN 22~45	-
MOTOR_Vcc	-	Main power supply (shared with HC05/HC06)
GND	GND	-
NRF24L01
IRQ	-	-
MOSI	PIN 51	-
CNS	PIN 46	-
VCC	3.3V PIN	MCU provides the power
MISO	PIN 50	-
SCK	PIN 52	-
CE	PIN 47	-
GND	GND	-
MCU_POWER
VIN	-	MCU power supply (separate power supply from the main power supply)
GND	GND	-
SEN0142(MPU6050)
INT	-	-
SCL	PIN 21	-
SDA	PIN 20	-
GND	GND	-
VIN	5V PIN	MCU provides the power
OV7670
VCC	3.3V PIN	MCU provides the power
SCL	PIN 21	-
VS	PIN 17	-
PLK	PIN 16	-
D7	PIN 48	-
D5	PIN 49	-
D3	PIN 2	-
D1	PIN 3	-
D0	PIN 4	-
D2	PIN 5	-
D4	PIN 6	-
D6	PIN 7	-
XLK	PIN 9	-
HS	PIN 8	-
SDA	PIN 20	-
GND	GND	-
Other Pins
3.3V	3.3V PIN	-
5V	5V PIN	-
12	PIN 12	-
11	PIN 11	-
10	PIN 10	-
A0 (Analog Read)	A0 PIN	-
A1 (Analog Read)	A1 PIN	-
A2 (Analog Read)	A2 PIN	-
C1 (+)	-	Connect to the main power supply
C2 (+)	-	Connect to the main power supply
C3 (+)	3.3V PIN	-
C4 (+)	3.3V PIN	-
C5 (+)	3.3V PIN	-