Stepper Motor: 28BYJ-48
The 28BYJ-48 is a 5-wire unipolar stepper motor that runs on 5 volts. The detailed specs of the 28BYJ-48 stepper motor are shown below:
| Motor Type | Unipolar stepper motor |
| Connection Type | 5-wire connection (to the motor controller): Blue, Pink, Yellow, Orange, Red |
| Voltage | 5 Volts DC |
| Number of Phases | 4 |
| Operating Frequency (PPS) | 100Hz |
| Step Mode | Half-Step Mode: 8-step control signal sequence (recommended) Full-Step Mode: 4-step control signal sequence |
| Step Angle | Half-Step Mode: 5.625º per step / 64 steps per revolution of the internal motor shaft. Full-Step Mode: 11.25º per step / 32 steps per revolution of the internal motor shaft |
| Gear ratio | The manufacturer specifies: 64:1 Experimental result: 63.68395:1 Full revolution = steps per motor rotation x gear ratio For half-step: 64 steps per motor rotation x 63.68395 gear ratio ≒ 4076 steps per full revolution |
| Step Angle (1-2 phase) | 5.625º / 64 |
Step Sequence
The 28BYJ-48 is a Unipolar Stepper Motor. It has 4 coils of wire that are powered sequentially to make the magnetic motor shaft spin. When using the full-step method, 2 of the 4 coils are powered at each step. For the half-step mode, the first step is to power coil 1, then coil 1 and 2 together, then coil 2 only, and so on. With 4 coils, the half-step mode has 8 different signals. The following table shows the steps for half- and full-step modes.
WAVE DRIVE: 1-Phase at a Time (Full-Step)
| A IN4 |
B IN3 |
C IN2 |
D IN1 |
|
| Step 0 | X | |||
| Step 1 | X | |||
| Step 2 | X | |||
| Step 3 | X |
Simplest, but least used.
HALF STEP: 1 or 2 Phases at a Time (Half-Step)
| A IN4 |
B IN3 |
C IN2 |
D IN1 |
|
| Step 0 | X | |||
| Step 1 | X | X | ||
| Step 2 | X | |||
| Step 3 | X | X | ||
| Step 4 | X | |||
| Step 5 | X | X | ||
| Step 6 | X | |||
| Step 7 | X | X |
Smallest step angle. Medium torque.
FULL STEP: 2 Phases at a Time (Full-Step)
| A IN4 |
B IN3 |
C IN2 |
D IN1 |
|
| Step 0 | X | X | ||
| Step 1 | X | X | ||
| Step 2 | X | X | ||
| Step 3 | X | X |
Strongest torque.