Microcontrollers cannot drive motor and relays because of its high current requirements. In order to drive them, we need special current drivers and Motor relay board comes into the picture because of these requirements.
The Motor Relay Board drives motors and relays by supplying sufficient current. It can drive one Relay and four DC Motor or one stepper motor at a time.
Motor Relay Board
The Motor relay board eases the task of interfacing external motor and AC devices with the PIC Microcontroller. It has ULN2003 drivers for high current applications like Motor driving and Relay driving circuits for AC device interfacing.
Using the provided relay circuit, 230V devices can be controlled. This section is helpful for automating the ON and OFF.
The DC motor can be controlled using this section, there is 4 ULN2003 driver controlled lines for driving motors and each provides sufficient current to control the DC motor.
There is an alternate header, J3 for accessing individual pins.
| J3 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Pin Name | Port 0 | Port 1 | Port 2 | Port 3 | Port 4 | Port 5 | Port 6 | Port 7 |
The Jumper description is as below, J4.
| J4 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Pin Name | Relay | Relay | Relay | Relay | Motor A | Motor B | Motor C | Motor D |
The Relay and Motor inputs can be directly accessed by the header J5.
| J5 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Pin Name | Relay | Relay | Relay | Relay | Motor A | Motor B | Motor C | Motor D |
Terminal blocks are used for connecting Motor, external supply and relay controlled equipment. There are three terminal blocks. One is for Motor which is a 7 pin, another one a 2 pin for connecting external 12V supply and 3-pin terminal block is used for connecting relay inputs and outputs.
Pin arrangements in terminal blocks are as below.
| J1 | 1 | 2 | 3 |
| Pin Name | NC | COM | NO |
NC – Normally Closed
COM – Common
NO – Normally open
| J8 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| Pin Name | VCC | Motor 1 | Motor 2 | Motor 3 | Motor 4 | GND | GND |
VCC – Supply from External 12V or internal 9V whichever is higher
| J6 | 1 | 2 |
| Pin Name | 12V | GND |
12V – External power for motor
GND – Ground
There are two power headers available in this board, J9 for 9V and J7 for 5V.
| J7 | 1 | 2 | 3 | 4 |
| Pin Name | 5V | 5V | GND | GND |
| J9 | 1 | 2 | 3 | 4 |
| Pin Name | 9V | 9V | GND | GND |
There are 4 lines for motor control and both DC motor and stepper motor can be interfaced to the board. The motor can be interfaced to a terminal block, J8. The pins 2, 3, 4 and 5 are for motor lines.
For a Unipolar stepper motor, connect 4 lines to the motor terminals and a common terminal to the VCC. Put the jumper cap over 5, 6, 7 and 8 pins of J4 to connect pins to the microcontroller port.
For a Bipolar stepper motor, connect 4 lines to each of the terminals. Put the jumper cap over 5, 6, 7 and 8 pins of J4.
For DC motor, connect the motor line to the any one of the motor terminals and VCC to the common. Connect the jumper cap on the J4 for the corresponding pin.
The relay can be operated using any one of the first 4 port pins. Select the pin using the jumper cap on J4.
The relay has 3 terminals to connect,
Connect the input in COM terminal. NO terminal will be connected to the COM terminal during the Relay OFF condition and NC will be connected to the COM terminal during ON condition. The relay can be used to control 230V devices.