Control 28BYJ-48 Stepper Motor with ULN2003 Driver & Arduino

The 28BYJ-48 Stepper Motor

The 28BYJ-48 is a 5-wire unipolar stepper motor that runs on 5V. It’s perfect for projects that require precise positioning, like opening and closing a vent.Because the motor does not use contact brushes, it has a relatively precise movement and is quite reliable.Despite its small size, the motor delivers a decent torque of 34.3 mN.m at a speed of around 15 RPM. It provides good torque even at a standstill and maintains it as long as the motor receives power.

The red wire is always pulled HIGH, so when the other lead is pulled LOW, the phase is energized. The stepper motor rotates only when the phases are energized in a logical sequence known as a step sequence.

Pinout

The 28BYJ-48 stepper motor has five wires. The pinout is as follows:

Gear Reduction Ratio

According to the data sheet, when the 28BYJ-48 motor is operated in full-step mode, each step corresponds to a rotation of 11.25°. This means there are 32 steps per revolution (360°/11.25° = 32).In addition, the motor features a 1/64 reduction gear set (actually, it is 1/63.68395, but 1/64 is a good enough approximation for most purposes).  This means that there are in fact 2038 steps (32*63.68395 steps per revolution = 2037.8864 approximately 2038 steps).

Technical Specifications

Here are the specifications: