Page 250 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

10.14 Microcontroller stepper motor circuit

Table 10.4 Half-Step Transistor
Q1 Q2 Q3 Q4 Port B Output (decimal)
On — — — 1
On On — — 3
— On — — 2
— On On — 6
— — On — 4
— — On On 12
— — — On 8 229
On — — On 9

properly or the current load of the stepper motor may be too
great. Solution: Use TIP 120 transistors.
3. You have the stepper motor improperly wired into the circuit.
Check the coils using an ohmmeter and rewire if necessary.
4. The pulse frequency is too high. If the pulses to the stepper
motor are going faster than the motor can react, the motor
will malfunction. The pulse frequency is controlled by the ti
variable in the program. Increasing the value of this variable
will slow down the pulse frequency to the stepper motor. The
solution to this is to reduce the pulse frequency.

Using a PIC microcontroller and a UCN-5804 stepper
motor IC

We have controlled the stepper motor directly from the PIC chip.
We have also built a stepper motor controller using dedicated
stepper ICs. By incorporating stepper motor controller chips into
the PIC microcontroller design, we can derive benefits from both

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