Texas Instruments DRV8846 User manual

User's Guide
SLLU203A–June 2014–Revised March 2015
DRV8846 Evaluation Module
This document is provided with the DRV8846 customer evaluation module (EVM) as a supplement to the
DRV8846 (SLLSEK2) datasheet. It details the hardware implementation of the EVM.
Contents
1 PCB (Top View).............................................................................................................. 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 Motor Control Frame (Includes Start/Stop Steps and Move Steps).......................................... 6
2.7 Schematic and Bill of Materials (BOM) .......................................................................... 9
Appendix A Driver Installation Instructions ................................................................................... 12
List of Figures
1 Connections .................................................................................................................. 3
2 DRV8846 Schematic (1 of 2)............................................................................................... 9
3 DRV8846 Schematic (2 of 2) ............................................................................................. 10
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PCB (Top View) www.ti.com
1 PCB (Top View)
2 Introduction
The DRV8846 customer EVM is a platform revolving around the DRV8846, a low voltage dual H-bridge
driver and highly configurable power stage. This device has been optimized to drive a single bipolar
stepper with up to 32 degrees of internally generated microstepping.
The EVM houses an MSP430 microcontroller and a USB interface chip. The USB chip allows for serial
communications from a PC computer where a Microsoft®Windows®application is used to schedule serial
commands. These commands can be used to control each of the device’s signals, and drive the stepper
motor by issuing the step commands at the desired rate.
The microcontroller firmware operates using 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 DRV8846EVM offers access to VM (motor voltage) power rail via a terminal block (J1). A set of test
clips in parallel with the terminal block allows for the monitoring of the input power rail.
Apply VM according to datasheet-recommended parameters.
NOTE: VDD for the microcontroller is derived from the micro USB connector.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
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www.ti.com Introduction
Figure 1. Connections
2.2 Test Points
A 0.100 in pitch header connector (J4) is used to provide access to every device signal in the event a
different microcontroller is to be employed. To disconnect the internal MSP430 microcontroller, remove
resistor packs R5 and R6. Table 1 describes the connections available on the J4 header. Each header pin
is labeled on the evaluation module, and matches the pin of the DRV8846.
Table 1. Descriptions of the Connections Available on the J4 Header
Header Label Description
V3P3R 3.3 V after 33-Ωresistor
nFAULT Fault output
nSLEEP Sleep Mode input
RSVD Adaptive DECay input
DIR Direction input
nENBL Stepper motor enable
STEP Step input
M0 Step mode
M1 Step mode
TOFF_SEL Off-time selection
VREF Scale voltage to set IFS
VINT Internal supply voltage
I0 Torque (current level)
I1 Torque (current level)
DEC0 Decay mode
DEC1 Decay mode
GND Ground
GND Ground
3
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VINT
VREF    (VREF _ slider 4)
4095
= ´ ´
VREF
I    TORQUE StepModifier
FS 6.6 RISENSE
= ´ ´
´
Introduction www.ti.com
2.3 Jumpers
There are no jumpers on the DRV8846EVM module.
2.4 Motor Outputs
Two motor connectors are provided. Connectors J2 and J3 are available as shown in Figure 1.
2.5 Operation of the EVM
Use the following steps to operate the EVM.
1. Install the drivers and GUI. Refer to Appendix A at the end of this document for instructions.
2. Connect the wires of the stepper motor to terminals AOUT1, AOUT2, BOUT1, and BOUT2.
3. Connect the VM power supply but do not apply power at this step.
4. Connect the USB between the PC and the EVM. Open the GUI by selecting the launcher.exe file. It
may take up to 15 seconds to establish connection.
(a) Once the USB connection is established, the Status LED will begin to blink.
5. Apply 12 V to the VM and GND connections.
6. Configure the current settings, step and decay modes, torque, and pwm off time as desired as shown
in the following image:
The current is calculated using the VREF slider, the Sense resistor value, the Torque setting, and the
Step mode setting using the formula.
(1)
Where StepModifier is 0.71 for full step and 1.0 for other STEP MODE settings
The 12-bit DAC channel 0 is connected to the DRV8846 analog input VREF. Changing the DAC digital
value from 0 to 4092 in steps of 4, changes the analog voltage at the VREF pin from 0 V to VINT V.
See Equation 2.
(2)
Where VINT is the output of the DRV8846 pin and VREF_slider is the slider value from 0 to 1023.
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www.ti.com Introduction
7. Wake and Enable the device for operation.
(a) After setting up the controls signals for the DRV8846, enabling the DRV8846 requires selecting
both the WAKE and ENABLE buttons. When the WAKE button or ENABLE button are selected, the
circle to the left of the button will toggle from red to green.
(b) The WAKE button, which controls the nSLEEP pin, is used to wake the DRV8846. The ENABLE
button, which controls the nENBL pin, is used to enable the DRV8846 outputs.
(c) A message which states that *Both WAKE and ENABLE must be Green to enable the motor control
buttons will be visible until both the WAKE and ENABLE buttons are activated. Once these two
buttons have been activated, the message disappears and the Start/Stop and Move Steps buttons
will be available.
(d) If the WAKE or ENABLE buttons are selected during motor operation, the motor is immediately
stopped and the STEP control signal from the microcontroller is reset.
8. The DRV8846 EVM is now awake and can be commanded to turn the motor. This can be done by
either selecting the Start/Stop Steps,Move # of Steps, or Reciprocate buttons.
The Start/Stop Steps button is used to run the motor indefinitely. The motor will accelerate to the target
speed and run until the Start/Stop Steps button is selected. When the Start/Stop Steps button is
selected, the red button will change to green, and the Move Steps and Reciprocate buttons will be
disabled.
The Move Steps button is used to allow movement of an exact number of steps. When the Move Steps
button is selected, the red button to the left of Move Steps will turn green, and the Start/Stop Steps and
Reciprocate buttons are disabled until the number of steps have completed.
The Reciprocate button is a special case of the Move Steps. When selected, the motor will advance
the specified number of steps in the direction initially set by the control inputs. After a short pause, the
motor will then advance the same number of steps in the opposite direction. This sequence is repeated
until the Reciprocate button is selected.
When the Reciprocate button is selected, the red button to the left of Reciprocate will turn green, and
the Start/Stop Steps and Move # of Steps buttons are disabled until the number of steps have
completed.
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2.6 Motor Control Frame (Includes Start/Stop Steps and Move Steps)
The GUI has an area which offers access to a series of very useful stepper control algorithms. This area
allows for determining the best current settings during running at various speeds, and when holding torque
is applied.
Motor motion can only happen by using an acceleration profile which will be detailed later on. A detailed
explanation of each stepper control section follows.
This frame allows the configuration and running of the stepper with the direction as specified by the DIR
checkbox, with the current decay mode as specified under the Decay Mode checkbox and the
microstepping resolution as specified under the Step Mode drop down box.
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Stopping SpeedStarting Speed
Steps to Stop
Number of Steps
Acceleration Rate
Target Speed
www.ti.com Introduction
The Motion Control frame gathers user information regarding stepping rate, or motor speed. An
acceleration profile is employed to start at a programmable speed and increase stepping rate until
reaching the programmable desired speed.
An internal 8-MHz timer is used to measure time and generate the steps on a timely manner. The GUI will
send the information to the microcontroller as PPS, and the microcontroller will transform it into the
respective clock cycles needed for the timer to generate accurate STEP pulse timing.
2.6.1 Start/Stop Steps
The acceleration profile is coded inside of the microcontroller to accept both the starting speed PPS and
target speed PPS as a clock cycle number. When the start steps command is issued (Starts/Steps button
is selected), the PWM timer generates steps at a rate specified by the start speed PPS parameter.
When accelerating or decelerating, PPS is adjusted every 32 ms, based on the integer value of PPSPS/32
ms. If a non-zero value of PPSPS is entered, a minimum value of 1 is used. The step rate is increased by
the calculated value until the target speed is reached.
The very same start steps command computes how frequent automatic speed updates are issued and a
second timer is used to change the speed according to the programmed acceleration rate profile.
Once the target speed (PPS) is reached, the acceleration profile ends and the motor stays running until
the stop stepper command is issued (Start/Stop Steps button is selected again). When the stepper is
commanded to stop, the controller does exactly as it did while accelerating, but in reverse to decelerate
until the stop speed PPS is reached, in which case the motor fully stops.
A second motor actuation is provided by the Move # of Steps and Reciprocate commands in which a
programmed number of steps are issued and then the motor stopped. The acceleration and deceleration
profiles work similarly as before, except when the deceleration starts and when the motor actually stops
are a function of the Steps to Stop and deceleration rate parameters.
This second motor actuation is adjusted automatically for rising edge or rising and falling edge settings in
the STEP MODE.
The following figure shows the acceleration profile and the role each parameter plays during speed
computation:
2.6.2 Move Steps
If the user desires to move the stepper a certain number of steps, this can be accomplished by using the
move steps function. Parameters from the other frames are reused and its utilization is as explained
previously. Two new parameters have been added to properly control the limited number of steps
actuation.
Number of Steps: Number of steps the controller will issue.
Steps to Stop: The controller is continuously monitoring the step being issued and when the current step
is equal to the steps to stop parameter, a deceleration profile is issued. If Steps to Stop is larger than the
number of steps, then the motor stops abruptly and without undergoing a deceleration profile.
When a deceleration profile is issued, the controller decreases the speed until reaching the stop speed
value. If the number of steps parameter is met before the deceleration profile is complete, then the motor
stops at the current speed. If the stop speed is met before all the number of steps is issued, then the
motor rotates at the stop speed value until all the steps are executed.
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Introduction www.ti.com
Ideally, the system should be tuned to resemble the case in which the controller executes all the
commanded steps at a speed as close as possible to the stop speed. In the event this is not possible, due
to the particular parameters being chosen, stopping the motor at a speed very close to the stop speed is
often good enough to ensure good motion quality and application performance.
The following figure shows the three conditions possible when stopping and the action taken:
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A A
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5/13/2014
DRV8846EVM_RevA.SchDoc
Sheet Title:
Size:
Mod. Date:
File:
Sheet: of
Bhttp://www.ti.com
Contact: http://www.ti.com/support
DRV8846EVMProject Title:
Designed for: Public Release
Assembly Variant: 001
© Tex as Instruments 2014
Drawn By:
Engineer: Rick Duncan
Texas Instruments and/or its licensors do not warrant the accuracy or completeness of this specification or any information contained therein. Te xas Instruments and/or its licensors do not
warrant that this design will meet the specifications, will be suitable for your application or fit for any particular purpose, or will operate in an implementation. Texas Instruments and/or its
licensors do not warrant that the design is production worthy. You should completely validate and test your design implementation to confirm the system functionality for your application.
Not in version controlSVN Rev:
DRV8846EVMNumber: Rev: A
10µF
C1
VM
AOUT2
AOUT1
TOFF_SEL
10
nENBL
11
STEP
12 DIR 13
VREF 14
VM 15
NC 16
VINT 17
GND 18
ADEC 19
I0 20
I1 21
DEC0 22
nSLEEP 23
DEC1 24
PPAD
25
AOUT1
1
AISEN
2
AOUT2
3
BOUT2
4
BISEN
5
BOUT1
6
nFAULT
7
MO
8
M1
9
U1
DRV8846RGE
DEC1
GND
AOUT1
DEC0
GND
AOUT2
BOUT1
BISEN
BOUT2
DRV8846
nFAULT notification
GND
nFAULT
C
1A2
D1
D_LED_603_RED
0.1µF
C2
2.2µF
C3
1
2
J1
ED555/2DS
nSLEEP
nFAULT
4.99k
R3
BOUT1
BOUT2
VM
AISEN
VINT
VREF
DIR
I1
I0
M0
M1
TOFF_SEL
nENBL
STEP
ADEC
0.25
R1
0.25
R2
GND
510
R4
1
2
J2
ED555/2DS
1
2
J3
ED555/2DS
MSP_M1
MSP_TOFF_SEL
MSP_VREF
MSP_VINT
MSP_I0
MSP_I1
MSP_DEC0
MSP_DEC1
MSP_nFAULT
MSP_nSLEEP
MSP_ADEC
MSP_DIR
MSP_nENBL
MSP_STEP
MSP_M0
nSLEEP
ADEC
DIR
nENBL
STEP
M0
M1
TOFF_SEL
VREF
VINT
I0
I1
DEC0
DEC1
1
2
3
4
5
6
7
89
10
11
12
13
14
15
16
R5
EXB-2HV330JV
1
2
3
4
5
6
7
89
10
11
12
13
14
15
16
R6
EXB-2HV330JV
DEC1
DEC0
I1
I0
VINT
VREF
TOFF_SEL
M1
DIR
M0
STEP
nENBL
ADEC
nSLEEP
nFAULT
AOUT1 AOUT2
TEST POINTS & DEBUG MODE
BOUT1 BOUT2
VM
VM GND2 AOUT1 AOUT2 BOUT1 BOUT2
GNDGND
nFAULT
Remove R4 to
disable current flow
through diode
Motor Supply and
Outputs
VM range 4 to 16V
Connection to microcontroller
or external interface
Notes:
1) For normal operation, populate resistor packs R5 and R6
2) For external control, remove resistor packs R5,R6 and provide signals at J4
3) Signals can be observed at J4 during normal operation
GND
1GND 2
GND1
D3082-05
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
J4
HEADER_1X18
V3P3R
V3P3
V3P3R
V3P3R
GND
0.1µF
C12
GND
www.ti.com Introduction
2.7 Schematic and Bill of Materials (BOM)
2.7.1 DRV8846 Schematic
Figure 2 and Figure 3 illustrate the schematics for this EVM.
Figure 2. DRV8846 Schematic (1 of 2)
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2
2
3
3
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5
5
6
6
D D
C C
B B
A A
1 1
5/13/2014
DRV8846EVM_MSP430F2617_RevA.SchDoc
Sheet Title:
Size:
Mod. Date:
File:
Sheet: of
Bhttp://www.ti.com
Contact: http://www.ti.com/support
DRV8846EVMProject Title:
Designed for: Public Release
Assembly Variant: 001
© Tex as Instruments 2014
Drawn By:
Engineer: Rick Duncan
Texas Instruments and/or its licensors do not warrant the accuracy or completeness of this specification or any information contained therein. Te xas Instruments and/or its licensors do not
warrant that this design will meet the specifications, will be suitable for your application or fit for any particular purpose, or will operate in an implementation. Texas Instruments and/or its
licensors do not warrant that the design is production worthy. You should completely validate and test your design implementation to confirm the system functionality for your application.
Not in version controlSVN Rev:
DRV8846EVMNumber: Rev: A
MSP430 w JTAG Interface
USB TO UART
1
2
3
4
5
6
7
10
11
8
9
J6
ZX62-B-5PA(11)
TXD
1
DTR#
2
RTS#
3
VCCIO
4
RXD
5
RI#
6
GND
7
NC
8
DSR#
9
DCD#
10
CTS#
11
CBUS4
12
CBUS2
13
CBUS3
14 USBDP 15
USBDM 16
3V3OUT 17
GND 18
RST# 19
VCC 20
GND 21
CBUS1 22
CBUS0 23
NC 24
AGND 25
TEST 26
OSCI 27
OSCO 28
U3
FT232RL
0.1µF
C9
GND
V3P3
1 2
L1
MI0805K400R-10
GND
GND
RX
TX
TX
RX
V3P3
DVCC
1
P6.3/A3
2
P6.4/A4
3
P6.5/A5
4
P6.6/A6
5
P6.7/A7/SVSIN
6
VREF+
7
XIN
8
XOUT
9
VEREF+
10
VREF-/VEREF-
11
P1.0/TACLK/CAOUT
12
P1.1/TA0
13
P1.2/TA1
14
P1.3/TA2
15
P1.4/SMCLK
16
P1.5/TA0
17
P1.6/TA1
18
P1.7/TA2
19
P2.0/ACLK/CA2
20
P2.1/TAINCLK/CA3
21
P2.2/CAOUT/TA0/CA4
22
P2.3/CA0/TA1
23
P2.4/CA1/TA2
24
P2.5/ROSC/CA5
25
P2.6/ADC12CLK/CA6
26
P2.7/TA0/CA7
27
P3.0/UCB0STE/UCA0CLK
28
P3.1/UCB0SIMO/UCB0SD
29
P3.2/UCB0SOMI/UCB0SC
30
P3.3/UCB0CLK/UCA0STE
31
P3.4/UCA0TXD/UCA0SIM
32
P3.5/UCA0RXD 33
P3.6 34
P3.7 35
P4.0/TB0 36
P4.1/TB1 37
P4.2/TB2 38
P4.3 39
P4.4 40
P4.5 41
P4.6 42
P4.7/TBCLK 43
P5.0 44
P5.1 45
P5.2 46
P5.3 47
P5.4/MCLK 48
P5.5/SMCLK 49
P5.6/ACLK 50
P5.7/TBOUTH/SVSOUT 51
XT2OUT 52
XT2IN 53
TDO/TDI 54
TDI/TCLK 55
TMS 56
TCK 57
RST/NMI 58
P6.0/A0 59 P6.1/A1 60 P6.2/A2 61
AVSS 62
DVSS 63
AVCC 64
U2
MSP430F2617TPMR
GND
GND
GND
RST
V3P3
3.32k
R8
1 2
3 4
5 6
7 8
9 10
11 12
13 14
J5
PEC07DAAN
V3P3
MSP_DEC0
MSP_I1
MSP_I0
MSP_TOFF_SEL
MSP_M1
MSP_M0
GND
FTDI regulator used for 3.3V
STATUS
MSP_VREF
MSP_BVREF
330
R7
GND
STATUS
GND
RST
C
1A2
D2
4
1
3
2
S1
EVQP1D05M
MSP_CA7 MSP_DEC1
MSP_nFAULT
MSP_nSLEEP
MSP_ADEC
MSP_DIR
MSP_nENBL
MSP_STEP
MSP_VINT
GND
0.1µF
C10
0.1µF
C4
DM
DP
VBUS
0.1µF
C5
4.7µF
C11
0
R10
0
R9
DNP
DNP R9. If debug or
programming adapter is used
to power the MSP430,
remove R10 and populate R9
1µF
C8
GND
Introduction www.ti.com
Figure 3. DRV8846 Schematic (2 of 2)
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