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DRV8886AT
User Manual
19 pgs3.35 Mb0

Texas Instruments DRV8886AT User Manual

User's Guide
SLVUB16–February 2017
DRV8886AT Evaluation Module User's Guide
Contents
1 Board Overview .............................................................................................................. 2
2 Introduction ................................................................................................................... 2
2.1 Connectors .......................................................................................................... 2
2.2 Test Points........................................................................................................... 3
2.3 Jumpers.............................................................................................................. 4
2.4 Motor Outputs ....................................................................................................... 4
2.5 Operation of the EVM .............................................................................................. 4
2.6 Motion Control Frame (Includes Start/Stop Steps and Move Steps) ........................................ 7
2.7 EVM documentation................................................................................................ 9
Appendix A Driver and GUI Installation Instructions ........................................................................ 10
1 Top View of Typical Board Configuration (EVM Provided May Vary) ................................................ 2
2 Connections (DRV8885 EVM Shown Has Similar Connections)...................................................... 3
3 GUI at Startup................................................................................................................ 4
4 Wake and Enable Toggle Buttons......................................................................................... 5
5 Reciprocate Toggle Button................................................................................................. 6
6 Motor Motion Profile......................................................................................................... 7
7 Acceleration Profile.......................................................................................................... 8
8 Stop Conditions .............................................................................................................. 9
9 User Account Control Window............................................................................................ 10
10 EVM Setup Wizard......................................................................................................... 11
11 License Agreement ........................................................................................................ 11
12 Installation Folders ......................................................................................................... 12
13 GUI Composer Runtime Selection....................................................................................... 12
14 Possible Upgrade Question............................................................................................... 13
15 Ready to Install............................................................................................................. 13
16 Completed................................................................................................................... 14
1 Connections to DRV8886AT Using External Microcontroller .......................................................... 3
Trademarks
MSP430 is a trademark of Texas Instruments. Windows is a registered trademark of Microsoft Corporation. All other trademarks are the property of their respective owners.
List of Figures
List of Tables
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DRV8886AT Evaluation Module User's Guide
Copyright © 2017, Texas Instruments Incorporated
1
DRV8886AT
Motor
Connections
Power Connector
Microcontroller
Section
Micro
USB
Header
Board Overview
1 Board Overview
shows the top view of the printed circuit board (PCB).
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Figure 1. Top View of Typical Board Configuration (EVM Provided May Vary)
The DRV8886AT (U1) can operate at temperatures approaching 150ºC. This device should not be touched.
2 Introduction
The DRV8886AT customer EVM is a platform revolving around the DRV8886AT, a medium-voltage dual H-bridge driver and highly-configurable power stage. This device has been optimized to drive a single bipolar stepper with up to 16 degrees of internally generated microstepping.
The EVM houses an MSP430™ microcontroller and an USB interface chip. The USB chip allows for serial communications from a PC computer where a Windows®application is used to schedule serial commands. These commands can be used to control each of the device signals, and drive the stepper motor by issuing the step commands at the desired rate.
The microcontroller firmware operates using an internal index mode. This user's guide details the operation of the EVM, as well as the hardware configurability of the
evaluation module.
2.1 Connectors
The DRV8886AT EVM offers access to the VM (motor voltage) power rail through a terminal block (J1). A set of test clips in parallel with the terminal block allows for the monitoring of the input power rail.
The user must apply the VM voltage according to recommended parameters listed in the data sheet.
2
DRV8886AT Evaluation Module User's Guide
WARNING
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Connect
USB here
Connect Power and
Ground here
Connect Motor
here
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Introduction
NOTE: The VDD voltage for the microcontroller is derived from the microUSB connector.
2.2 Test Points
A 0.100-inch pitch header connector (J4) provides access to every device signal in the event that a different microcontroller is used. To disconnect the internal MSP430 microcontroller, remove the R3, R4, R5, and R6 resistors, and resistor pack R7. Table 1 describes the connections available on the J4 header. Each header pin is labeled on the evaluation module, and connects to a similarly named pin of the DRV8886AT.
Figure 2. Connections (DRV8885 EVM Shown Has Similar Connections)
Table 1. Connections to DRV8886AT Using External
Microcontroller
Header Label Description
V3P3R 3.3 V after 0 Ω resistor nFAULT Fault output nSLEEP Sleep Mode input RREF_R Chopping current selection DIR DIR, Direction input ENABLE ENABLE, Stepper motor enable STEP STEP, Step input USM0 M0, Step mode USM1 M1, Step mode TORQUE TRQ, Output current scale DECAY_R Decay Mode select after 0-Ω
resistor
DVDD Internal supply voltage to set DAC
voltage
GND Ground
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3
Introduction
2.3 Jumpers
The DRV8886ATEVM has no jumpers.
2.4 Motor Outputs
Two motor connectors are provided. shows the avaialable J2 and J3 connectors.
2.5 Operation of the EVM
Use the steps that follow to operate the EVM:
Step 1. Install the drivers and GUI. For instructions see Appendix A. Step 2. Connect the wires of the stepper motor to the AOUT1, AOUT2, BOUT1, and BOUT2
terminals. Step 3. Connect the VM power supply but do not apply power at this step. Step 4. Connect the USB cable between the PC and the EVM. When the USB is connected to the
EVM, the status LED will begin to blink. Step 5. Open the GUI. The GUI can be found in the start menu at Texas Instruments →
DRV8886_EVM → DRV8886_EVM X.Y.Z, where X, Y, and Z are the revision numbers. If a
shortcut was created, double-click on the shortcut to open the GUI. The GUI can take up to
30 s to establish a connection. If connection is not established, select the COM port under
the Options menu. The BaudRate is 9600.
NOTE: The DRV8886 EVM GUI is designed to control both the DRV8886AT EVM and the DRV8886
EVM. The GUI automatically identifies the device and changes the pulldown menus as needed.
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Step 6. Apply the desired voltage (6.5 to 37 V) to the VM and GND connections. Step 7. Configure the current settings, step mode, decay mode, and torque to the desired values as
shown in Figure 3.
4
DRV8886AT Evaluation Module User's Guide
Figure 3. GUI at Startup
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FS
1.232 VRREF_R
1.232
§ ·
u u u
¨ ¸ © ¹
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Introduction
The current is calculated using the VREF slider, the sense resistor value, the torque setting, and the step mode setting using Equation 1.
where
• StepModifier is 0.71 for full step and 1 for other STEP MODE settings (1)
The number 1.232 is based on the maximum current allowed using the configuration. If VRREF = 0 V, the maximum current is 1 A. The 12-bit DAC channel 1 is connected to the DRV8886AT analog input RREF through a 15-kΩ series resistor. The DAC voltage begins at 1.232 V (0%) and ends at 0 V (100%).
Step 8. After setting up the control signals for the DRV8886AT, select both the WAKE and ENABLE
toggle buttons to enable the DRV8886AT. When toggled, the WAKE or ENABLE status
toggles between red and green. The WAKE toggle button, which controls the nSLEEP pin, is used to wake the DRV8886AT. The
ENABLE toggle button, which controls the ENABLE pin, is used to enable the DRV8886AT outputs. A message stating Both WAKE and ENABLE must be green to enable the motor control buttons is
visible until both the WAKE and ENABLE toggle buttons are activated. When these two toggle buttons have been activated, the message disappears and the Start/Stop Steps and Move # of Steps toggle buttons are available.
If the WAKE or ENABLE toggle buttons are selected during motor operation, the motor is immediately stopped and the STEP control signal from the microcontroller is reset.
Figure 4. Wake and Enable Toggle Buttons
Step 9. The DRV8886AT EVM is now awake and can be commanded to turn the motor. Turning the
motor occurs by either selecting the Start/Stop Steps, Move # of Steps, or Reciprocate toggle
button.
The Start/Stop Steps toggle button is used to run the motor indefinitely. The motor will accelerate to the target speed and run until the Start/Stop Steps toggle button is selected. When the Start/Stop Steps toggle button is selected, the red button changes to green, and the Move Steps and Reciprocate toggle buttons are disabled.
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DRV8886AT Evaluation Module User's Guide
5
Introduction
The Move Steps toggle button is used to allow movement of an exact number of steps. When the Move Steps toggle button is selected, the Move Steps toggle button turns green, and the Start/Stop Steps and Reciprocate toggle buttons are disabled until the number of steps have completed.
The Reciprocate toggle button is a special case of the Move Steps option. When selected, the motor advances the specified number of steps in the direction initially set by the control inputs. After a short pause, the motor then advances the same number of steps in the opposite direction. This sequence is repeated until the Reciprocate toggle button is selected.
When the Reciprocate toggle button is selected, the Reciprocate toggle button turns green, and the Start/Stop Steps and Move # of Steps toggle buttons are disabled until the Reciprocate toggle button is set to red and the number of steps have completed.
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As an extra precaution, the motor can be stopped by selecting either the WAKE or ENABLE toggle buttons. When selected, the STEP commands are stopped and the motor control buttons are disabled. To re-enable motor control, set the WAKE and ENABLE toggle buttons to green.
6
DRV8886AT Evaluation Module User's Guide
Figure 5. Reciprocate Toggle Button
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