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3.5.2

Step by Step control

4

Schematic

Schematic

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Pressing the Start Steps button, will start the timer and pulses will be generated at the rate specified by
the decimal number at the PPS text box. Once the Start Steps button is pressed it becomes the Stepping
button. Press the Stepping button to stop the stepper motion.

When the motor is stepping, the Update Speed button becomes enabled. Speed can be updated by
modifying the PPS text box and then pressing the Update Speed button. The Update Speed button is
disabled every time the motor is not turning because the stepping has been halted by pressing the
Stepping button.

The Step Control frame has a series of tools to control the stepping of the motor on a predetermined
number of steps fashion.

The Pulse Step button allows for a single step to be issued. At the same time, the STEP Control check
box allows the control of the STEP signal in the same fashion that other GPIO signals on the Signals
frame could be set and cleared. Checked stands for HI and unchecked for LO. Remember that a STEP
takes place when STEP goes from LO to HI.

Figure 10. Step Control Frame

To move the motor a number of steps and then stop, fill the # of Steps text box with a decimal number
from 0 to 65535 and the motor will move that number of steps at the speed specified on the PPS text box.
No acceleration or deceleration takes place under this function.

The schematic can be found on the provided CD under the EVM Related folder.

12

Laser and Motor Drives

SLVA344A – July 2009 – Revised September 2009

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Summary of Contents for DRV8811EVM

Page 1: ...DRV8811EVM User s Guide Literature Number SLVA344A July 2009 Revised September 2009 ...

Page 2: ...2 SLVA344A July 2009 Revised September 2009 Submit Documentation Feedback ...

Page 3: ...811 Evaluation Board Windows Application Software 8 2 3 Running the Windows Application Software 8 3 Windows Application 8 3 1 Menu 9 3 2 DRV8811 GPIO Control Signals 9 3 3 Updating DAC Output for Current Control VREF DECAY 10 3 4 Updating DAC Output for Decay Control DECAY 10 3 5 Operating the Stepper Motor 10 4 Schematic 12 SLVA344A July 2009 Revised September 2009 Table of Contents 3 Submit Doc...

Page 4: ..._RD_EVM_R1p0 exe Main Screen 8 4 Acknowledgement Text Box 9 5 Signals Frame 9 6 Curent Control Frame 10 7 Current Control Frame 10 8 Step Rate 11 9 Speed Control Frame 11 10 Step Control Frame 12 4 List of Figures SLVA344A July 2009 Revised September 2009 Submit Documentation Feedback ...

Page 5: ...nd Motor Drives This document is provided as a supplement to the DRV8811 datasheet It details the hardware implementation of the DRV8811 customer evaluation module EVM SLVA344A July 2009 Revised September 2009 Laser and Motor Drives 5 Submit Documentation Feedback ...

Page 6: ...ands from the PC and generates control signals to the driver device and the DRV8811 device with access to all signals for a complete evaluation The DRV8811 customer EVM uses a combination of terminal blocks and test clips for the application monitoring of power The only power rail the user must supply is VM for the device s power stage VDD for logic levels is internally generated from the USB conn...

Page 7: ...selects an analog voltage derived from the MSP430 s digital to analog converter channel 0 DAC0 Figure 2 DECAY SELECT Jumper To configure the DECAY SELECT jumper Figure 2 a selects an analog voltage derived from VDD through a voltage divider implemented as a potentiometer R6 Figure 2 b selects an analog voltage derived from the MSP430 s digital to analog converter channel 1 DAC1 There are three way...

Page 8: ...plication is the software counterpart for the DRV8811 EVM It is in charge of connecting to the MSP430 microcontroller via a USB connection which in turn selects the proper logic state for the DRV8811 control signals The graphical user interface GUI has been designed to allow for all of the DRV8811 device s functionality to be tested without having to intervene with the hardware except for the prop...

Page 9: ...he application the order of events should be 1 Go to Settings Port and choose the COM port where the USB virtual COM port device has been configured to work If the COM port is 4 then this step can be skipped as application defaults to COM4 2 Press Connect If the port is available the menu changes the Connect caption to Disconnect Press Disconnect to disable the serial communications 1 4 0 should r...

Page 10: ...e output voltage and DAC_VALUE is a number from 0 to 4095 If the DRV8811 EVM has been configured to accept DECAY analog voltages through the MSP430 microcontroller interface JP6 is set to INT then the slider bar on the Current Control frame can be used to set the DECAY voltage Figure 7 Current Control Frame The MSP430F1612 12 bit DAC channel 1 is connected to the DRV8811 DECAY analog input Changin...

Page 11: ...to reach the PPS speed Acceleration rate is an 8 bit number 0 to 255 that gets added to the current PPS speed and time base is an 8 bit number 0 to 255 that specifies how many milliseconds will elapse from one speed increase to the next Once the specified PPS speed has been achieved the acceleration stops Figure 8 Step Rate When the motor is commanded to stop the inverse of the description above o...

Page 12: ...ontrol the stepping of the motor on a predetermined number of steps fashion The Pulse Step button allows for a single step to be issued At the same time the STEP Control check box allows the control of the STEP signal in the same fashion that other GPIO signals on the Signals frame could be set and cleared Checked stands for HI and unchecked for LO Remember that a STEP takes place when STEP goes f...

Page 13: ...ice TI is not responsible or liable for any such statements TI products are not authorized for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parties have executed an agreement specifically governing such use Buyers represent that they have all necessary expertis...

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