SparkFun ProDriver and Mini Stepper Motor Driver Hookup Guide

Contributors:

QCPete, santaimpersonator

Hardware Overview - Mini Stepper Motor Driver

Board Dimensions

Below, are basic drawings of the board dimensions and component layout for the SparkFun Mini Stepper Motor Driver. For more detailed measurements, users should download and open the KiCad files from the GitHub repository or from the Documents tab on the product page. It should be noted that the layout of the PTH breakout pins is compatible with breadboards and that the pins on the edge of the board, have a .10" spacing for headers (or to solder more permanent connections).

SparkFun Mini Stepper Motor Driver board dimensions. (Click to enlarge)

Power

Unlike the ProDriver, the Mini Stepper Motor Driver requires two power inputs:

3V3 - Supplies the I/O voltage for the pull-up resistors on the M0 - M3 pins. Additionally, it is connected to a voltage divider that provides the reference voltage (VREF) for the drive current, limitation.
VM - Powers the TC78H670FTG motor driver IC and supplies the output power for driving a bipolar stepper motor (or DC motors).

I/O Voltage Level

The 3.3V PTH connection provides the I/O voltage level for the pul-up resistors on the M0 - M3 pins. It is also used for the hardware configuration for the drive current, limitation on the TC78H670FTG.

The 3V3 pin on the Mini Stepper Motor Driver. (Click to enlarge)

Note: While the TC78H670FTG is compatible with I/O voltages from 1.5-5.5V, the voltage divider that is configures the drive current, also utilizes this connection. Therefore, precautionary steps should be taken because the voltage divider provides the reference voltage (VREF), which has a maximum input range of 1.8V and the resistor combination of the voltage divider, was calculated with the assumption that 3.3V would be provided.

Motor

⚡ Note: Do not connect or disconnect the motor while the Mini Stepper Motor Driver is powered; as it may damage the motor driver IC.

In order to drive a motor, users will need a power supply with an voltage between 3.3 - 16V and can source at least 2A. Users will connect their power supply to the VM and GND pins on the Mini Stepper Motor Driver.

The VM and GND pins on the Mini Stepper Motor Driver. (Click to enlarge)

⚡ Note: For the Mini Stepper Motor Driver, we recommend that users attach an electrolytic capacitor (>50µF) between the VM and GND pins.

Users that have a power supply with a DC barrel jack, may find some of these accessories useful:

DC Barrel Jack Adapter - Female

PRT-10288

$3.50

Favorited Favorite 25

Barrel Jack Power Switch - M-F (3")

COM-11705

$2.75

Favorited Favorite 32

Barrel Jack Extension Cable - M-F (6 ft)

COM-11707

$2.10

Favorited Favorite 11

Barrel Jack Extension Cable - M-F (3 ft)

COM-11706

$1.95

Favorited Favorite 8

Pin Connections

The Mini Stepper Motor Driver was designed with PTH breakout pins in a compact layout that is compatible with breadboards.

The PTH pins on the Mini Stepper Motor Driver. (Click to enlarge)

More details on these pins are laid out in the following sections below, excluding the power pins. Details for the 3V3 and VM pins are described in the power section above.

Input Control Pins

The input control pins are used to interface directly with the TC78H670FTG motor driver. For more details on the functions of the pins listed below, check out the datasheet for the TC78H670FTG.

The input control connections on the Mini Stepper Motor Driver. (Click to enlarge)

Pin Name	Label	Description	Operating Something
Ground Reference	`GND`	Ground (i.e. the 0V reference)	0V
Standby	`STBY`	This pin is used to either place the motor driver in standby or initiate one of the control methods. Low: Motor driver is in standby; and the motor is released from any of the control methods. High: On the up edge, the motor driver is configured for clock-in stepping or serial communication control based on the input state of the `M0`, `M1`, `M2`, and `M3` pins.	0 to 3.3V
Enable	`EN`	When the motor driver is configured for clock-in stepping, this pin is used to enable the motor output ON or OFF. Low: Motor is off; all of the H-Bridge MOSFETs turn off and become high impedance (Hi-Z). High: Motor is on; after the VM reaches the target voltage and becomes stable.	0 to 3.3V (Default: Low or 0V)
Error Detection Flag Output	`ERR`	If a thermal shutdown (TSD), over current (ISD), or motor load open (OPD) error, is triggerd, the pin output is pulled low. Under a normal operating status, the level of `ERR` pin is equal to the `EN` control voltage from outside. The error flag can be released by reconnecting the `VM` power or by setting the device to standby. Low: An error has been detected/triggered. High: Operation status is normal.	0 to 3.3V
MODE0 UP-DW (Clock-in) S_DATA (Serial)	`M0`	MODE0: Utilized to configure the conrol method of the motor driver, when the standby pin is released. Based upon that control method, the pin will then function as one of the following inputs: Serial Communication: Serial Data Input (S_DATA) In serial mode, this line contains the serial data commands in a 32-bit format. After the serial setting is configured, the output is updated with the timing of the `LATCH` signal. Clock-in Stepping (Variable Mode Only): Step Mode Setting Input (UP-DW) Low:* Change step mode to high resolution High: Change step mode to Low resolution	0 to 3.3V (Default: High or 3.3V)
MODE1 SET_EN (Clock-in) LATCH (Serial)	`M1`	MODE1: Utilized to configure the conrol method of the motor driver, when the standby pin is released. Based upon that control method, the pin will then function as one of the following inputs: Serial Communication: Latch Enable Pin (LATCH) In serial mode, this line indicates the end of a data command. Clock-in Stepping: Step Mode- Setting Enable Pin (SET_EN) Low: Voids changes to the step size resolution setting. High: Allow changes to the step size resolution setting. (Only available for Variable Mode)	0 to 3.3V (Default: High or 3.3V)
MODE2 CLK (Clock-in) S_CLK (Serial)	`STEP/M2`	MODE2: Utilized to configure the conrol method of the motor driver, when the standby pin is released. Based upon that control method, the pin will then function as one of the following inputs: Serial Communication: Serial Clock Input Pin (S_CLK) In serial mode, this line contains the clock signal for serial data commands. Clock-in Stepping: Step Clock Input Pin (CLK) Up-Edge: Shifts the electrical angle by a single step (size). Down-Edge: N/A	0 to 3.3V (Default: High or 3.3V)
MODE3 CW-CCW (Clock-in)	`DIR/M3`	MODE3: Utilized to configure the conrol method of the motor driver, when the standby pin is released. The pin will then, only function as an input for clock-in stepping: Clock-in Stepping: Current Direction Setup Pin (CW-CCW) Low: Counter-clockwise operation (CCW) High: Clockwise operation (CCW)	0 to 3.3V (Default: High or 3.3V)
3.3V Input	`3V3`	Provides the I/O voltage for the `M0`, `M1`, `M2`, and `M3` pins, through the connected pull-up resistors. It also provides the supply voltage of the voltage divider for the Current Threshold Reference (`VREF`).	3.3V
Current Threshold Reference	`VREF`	Connected to the 10 kΩ potentiometer that controls the maximum drive current to the stepper motor coils. I_out (max) = 1.1 × V_ref (V)	0 to 1.8 V (assuming a 3.3V input voltage)

⚡ Note: From the datasheet, the TC78H670FTG is compatible with 3.3 and 5V logic levels on the control pins. The electrical specifications for the input voltage listed at a 5.5V maximum, with a 1.5 and 0.7V threshold on the high and low signals respectively. For more details, check out page 31 of the datasheet and the schematic for the Mini Stepper Motor Driver.

Output Channel Pins

The output channel pins are used to drive the coils of the stepper motor. The paired outputs are connected to the two H-Bridges of the motor driver.

The output motor driver channels on the Mini Stepper Motor Driver. (Click to enlarge)

⚡ Note: Do not connect or disconnect the motor while the Mini Stepper Motor Driver is powered; as it may damage the motor driver IC.

Pin Name	Label	Description
Positive "A" Channel Output	`A+`	The "A" channel motor output (+) pin
Negative "A" Channel Output	`A-`	The "A" channel motor output (-) pin
Positive "B" Channel Output	`B+`	The "B" channel motor output (+) pin
Negative "B" Channel Output	`B-`	The "B" channel motor output (-) pin

Useful Resources on Stepper Motors:

For basic information on stepper motors, users should check out our Motors and Selecting the Right One tutorial. Additionally, we have included a few YouTube videos, below, that help explain the theory of the stepping functionality behind stepper motors. Users who have stepper motors with more than four wires, may also find this article enlightening.

Motors and Selecting the Right One

December 12, 2013

Learn all about different kinds of motors and how they operate.

Favorited Favorite 46

An introductory video on stepper motor basics. Video courtesy of LearnEngineering.

An introductory video on stepper motor functionality. Video courtesy of GreatScott!.

A more in-depth video on stepper motor functionality. Video courtesy of Nanotec.

TC78H670FTG Motor Driver

The Mini Stepper Motor Driver operates with the Toshiba TC78H670FTG stepper motor driver. The TC78H670FTG is a 2-phase stepping motor driver, intended for bipolar stepper motors. The chip features two H-Bridge motor drivers that provide users with step size resolutions ranging from full steps, half steps, and micro-stepping down to a 1/128 of a step. The TC78H670FTG can be controlled with the standard clock-in stepping, but it also has an additional option for serial communication.

The Toshiba TC78H670FTG stepper motor driver IC on the Mini Stepper Motor Driver. (Click to enlarge)

Some of the advantages to the TC78H670FTG over a simple H-Bridge, include a standby function, selectable mixed decay, error detect flag output, clock- in stepping or serial communication control, software control of the current output, and a minimal parts bill of matierals (BOM). The serial command method is especially unique because it allows users to precisely control the phase, torque, current limit and mixed decay ratio of each coil during the motor operation. Additionally, while in most stepper motor driver ICs, an external trimpot is required to set the current limit; however, with the Mini Stepper Motor Driver, a simple serial command can be utilized to precisely adjust the current limit.

Characteristic	Description
Motor Power Supply Voltage:	2.5 to 16.0V
Output Current:	2.0A (max)
Control Methods:	Clock-in Stepping Serial Communication
Clock Frequency:	Clock-in Stepping: up to 400kHz Serial Communication: 1 to 15MHz
Step Size Resolution:	Discrete Steps Full step Half step Micro-Steps 1/4 step 1/8 step 1/16 step 1/32 step 1/64 step 1/128 step
Error Detection Functions:	Thermal Shutdown (TSD) Over-current Shutdown (ISD) Motor Load Open (OPD) Under Voltage Lockout (UVLO)

Enable/Error Pin Functionality

On the Mini Stepper Motor Driver the EN and ERR pins are broken out separately; however, these connections are tied to the same pin on the TC78H670FTG, which operates as a control input and output for error flags. A typical application of the EN/ERR pin with a microcontroller is displayed below.

The EN/ERR pin application from the datasheet. (Click to enlarge)

This duality allows the TC78H670FTG to give users control of the power to the motor drive channels; while also providing autonomous functionality to disable its own power, when an error flag is triggered and simultaneously, provide an output indicator on the same pin.

The EN and ERR pins on the Mini Stepper Motor Driver. (Click to enlarge)

H-Bridge Power Control

The EN pin controls the ON/OFF operation of the H-Bridges to the motor outputs. When the EN pin is low, all of the H-Bridge MOSFETs turn off and become high impedance (Hi-Z). Likewise, when the EN pin is set high, the motor channel outputs will be driven normally, based on the stepping controls.

The EN pin functionality from the datasheet. (Click to enlarge)

Note: Users should avoiding motor operation during any VM power-on and power-off cycles by setting the EN pin low to disable the motor channel outputs. The EN pin can be set high after the power supply reaches the target voltage and becomes stable.

Error Detection

The TC78H670FTG has a built-in functionality to detect thermal shutdown (TSD), over current (ISD), or motor load open (OPD) connection issues. When these errors are triggered, the ERR pin is pulled low. In a normal operating status, the level of ERR pin is equal to the EN control voltage from outside. After the error is triggered, the error flag can be released by reconnecting the VM power or by setting the device to standby.

Standby Function

The standby pin for the TC78H670FTG, is used to set up the control method for the motor driver. When the standby pin is low, the motor is released from any control methods and is in standby. On the up edge, of when the standby pin is set high, the motor driver is configured for clock-in stepping or serial communication control based on the input state of the M0, M1, M2, and M3 pins.

The configuration settings for the control methods, when the standby pin is set HIGH. Pulled from the datasheet. (Click to enlarge)

Control Methods

There are two different communication or control methods for users to interface with the Mini Stepper Motor Driver. The control method is configured by the input state of the M0 - M3 pins, when the TC78H670FTG is released from standby mode. The TC78H670FTG features the common clock-in stepping method and a more unique serial communication control.

Serial Communication Control

This method is unique to the TC78H670FTG Toshiba motor driver. The control logic allows users to manipulate registers through serial communication, which provide control over:

The motor rotation direction (or polarity)
Maximum current output, torque
OPD error detection
Selectable mixed decay (used to finely tune drive current to the motor)
Driving the motor rotation (full steps only).

(*For more details on the configuration options for the available registers, refer to Section 9 of the datasheet.)

Clock-In Stepping Control

This is a standard method for controlling most stepper motor drivers. By default, the Mini Stepper Motor Driver is configured for clock-in stepping in the fixed mode with a step resolution of 1/128 of a step.

Step Resolution Modes
With the clock-in control method, users can set up how the step resolution is configured. TC78H670FTG has the two modes for the step resolution settings, a variable mode and a fixed mode. These modes are also initiated by the input states of the M0 - M3 pins after releasing the standby pin, when the clock-in control method is configured. Below, is a table from the datasheet of the step resolution settings.
- Variable Mode: The motor can be started with full step resolution and the step resolution can be changed while the motor is operating.
- Fixed Mode: Once initiated, the step resolution is configured and maintained during the motor operation.

The step resolution configuration settings for the clock-in method, from the datasheet. (Click to enlarge)

Once clock-in stepping and the step resolution are configured together. The TC78H670FTG awaits for the up-edge of the clock (CLK) signal, for the STEP/M2 pin, to before it shifts the motor’s electrical angle per step. The DIR/M3 pin, controls the clockwise/counter-clockwise (CW-CCW) rotation direction of the motor for clock-in stepping.

When the DIR/M3 pin is low, the motor is driven with a counter-clockwise (CCW) operation.
Like wise, when the DIR/M3 pin is high, the motor is driven with a clockwise (CW) operation.

The DIR/M3 (CLK) and STEP/M2 (CW-CCW) pin functionality for clock-in stepping, from the datasheet. (Click to enlarge)

Step Resolution Transition

In variable mode, users can transition between different ranges of step size resolutions with the M0 and M1 pins. To enable the transition between step size resolutions, the M1 (SET_EN) pin must be high, when the TC78H670FTG is in variable mode for clock-in stepping. The M0 (UP-DW) pin is used to control the direction of the step size transition.

When the M0 pin is low, the step size resolution is increased to a smaller step size (i.e. from 1/4 to 1/8 of a step).
Like wise, when the M0 pin is high, the step size resolution is decreased to a larger step size (i.e. from 1/8 to 1/4 of a step).

The M1 (SET_EN) and M0 (UP-DW) pin functionality for transitioning the step size resolution during clock-in stepping, from the datasheet. (Click to enlarge)

The transition between step size resolutions occurs, synchronously with the up-edge of the next clock signal. It should also be noted, that the transition can only change the step size resolution one increment at a time (i.e. it takes three clock cycles to transition from a 1/4 step size, down three sizes, to a 1/32 step size resolution).

Maximum Drive Current

The maximum drive current for the Mini Stepper Motor Driver is limited to 2A (max). However, the peak output current can be controlled with two different methods.

Hardware: The first method controls the drive current through the reference voltage (Vref). The reference voltage, can be configured utilizing the external potentiometer or VREF breakout pin.

The potentiometer and VREF pin that can be utilized to control the maximum drive current.

For the hardware control, the maximum drive current can be calculated with the following equation:

Note: If the stepper motor movements are jittery, try increasing the drive current with the potentiometer.

Software: The second method controls the drive current through software. Utilizing serial communication to the TC78H670FTG, the registers can be configured to limit the maximum drive current. The maximum drive current can be calculated with the following equation, based on the configured registers:

Chopping Current Drive

Chopping is a technique that is used to control the average current per phase, by rapidly switching a relatively high output voltage to the motor coils, on and off. This technique improves the current rise time in the motor and improves the torque at high speeds, while maintaining a high efficiency in the constant current drive.

A table with the resistor values used to modify the OSCM oscillation and chopping frequency, from the datasheet. (Click to enlarge)

On the TC78H670FTG, the OSCM oscillation frequency (fOSCM) and chopping frequency (fchop) are adjusted with an external resistor (ROSC), connected to the OSCM pin. On the Mini Stepper Motor Driver, a 47 kΩ resistor is utilized.

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