1. Stepper Motor Control
Stepper Motor Control
Kayla Klein, Bach Nguyen, Nathan Hendrich
ET 226-01
Spring 2016

2. 2
Introduction
This report details the construction and parameters necessary for complete rotation of a stepper
motor through systematic pulsing. This system does not require use of a microcontroller.
Instead, the storage and shifting of data is passed through a shift register.
Background
The 8-bit shift register used is a serial-in/parallel-out. This means the stream of data collected
through one input, pin 14, produces 8 outputs. Figure 1 shows the pin layout of the 8-bit shift
register and table 1 details the description of each pin. The master reset and output enable,
respectively pin 10 and pin 13, is active when low and deactivated when high. When the storage
register clock input, pin 11, is active, the state of the serial data input, pin 14, is stored into the
register. Activating the storage register input, pin 12, moves the data from storage to the outputs.
Each time pin 12 is activated, the data shifts down, QA moves into QB, QB moves into QC, and so
on. To produce more than eight outputs, QH′ output, pin9, is linked into the serial input of
another shift register integrated circuit.

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Figure 1
SN74HC595
Table 1
Pin Symbol Description Pin Symbol Description
1 QB Parallel Output 16 VCC Supply Voltage
2 QC Parallel Output 15 QA Parallel Output
3 QD Parallel Output 14 SER Serial Data Input
4 QE Parallel Output 13 OE Output Enable (active low)
5 QF Parallel Output 12 RCLK Storage Register Input “Latch”
6 QG Parallel Output 11 SRCLK Storage Register Clock Input “Clock”
7 QH Parallel Output 10 SRCLR Master Reset (active low)
8 GND Ground (0V) 9 QH′ Serial Output

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Materials
(1) Bipolar Stepper Motor
(1) Proto board
(1) SN754410 -HBridge
(1) SNx4HC595 – Shift Register
(1) SN74LS08 – AND Gate
(1) SN7404 – Inverter
Wires
Method
Manual input of data is achieved through use of three normally open switches. See table 2 for
the connections needed to achieve manual input of data. The storage register clock, pin 11, and
serial data input, pin 14, are used to “clock” the significant data into storage. With the data input
stored, activating the storage register input, pin 12, moves the stream of data from storage to the
outputs. To create the desired effect of stepper motor rotation the data shown in table 3 cascades
and continuously loops through the shift register, where tn represents the clock pulse and Q is
the state of the serial data input at that time. By using a function generator in the protoboard, we
were able to continuously keep the shift register shifting by a value of zero every pulse to make
the step motor rotate by increasing the amplification of the pulse we were able to make it goes 10
times or 100 times faster than the initial inputs. An inverter and an AND gate were put into the

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circuit possibly be use to change the direction of the motor but unfortunately we were unable to
make it go in the reverse direction.
Table 2
Pin Symbol Connection
8 GND Ground
9 QH′ Serial Data Input
10 SRCLR High
11 SRCLK Switch 1
12 RCLK Switch 2
13 OE Ground
14 SER Switch 3
16 VCC +5V
Table 3
tn t0 t1 t2 t3 t4 t5 t6 t7
Q 1 0 0 0 1 0 0 0

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Schematics
Conclusion
The experiment was half way successful when we were able to shift in values into the
shift registers and make the motor goes one way. We were unsuccessful in making it goes

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backward. Sources of failures and errors: our understanding of the shift registers and the
Intergrated Circuits as a whole, the equipment failure, we have to switch out 2 protoboard and 3
chips because of malfunctions, human errors can also be included in the failure of this project.