Windows Application | www.ti.com |
A checked checkbox translates to a HI level on the respective control signal. A
3.3Updating DAC Output for Current Control (VREF/DECAY)
If the DRV8811 EVM has been configured to accept VREF analog voltages through the MSP430 microcontroller interface (JP1 is set to INT), then the slider bar on the Current Control frame can be used to set the VREF voltage.
Figure 6. Curent Control Frame
The MSP430F1612
2.5 V |
|
VREF=DAC_VALUE • | (1) |
4095 |
Where VREF is the output voltage and DAC_VALUE is a number from 0 to 4095.
3.4Updating DAC Output for Decay Control (DECAY)
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. Changing the DAC digital value from 0 to 4095, changes the analog voltage at the DECAY pin from 0 V to 2.5 V respectively. See Equation 2.
2.5 V |
|
DECAY=DAC_VALUE • | (2) |
4095 |
Where DECAY is the output voltage and DAC_VALUE is a number from 0 to 4095.
3.5Operating the Stepper Motor
3.5.1Turning the Stepper Motor
The Windows Application, in conjunction with the MSP430F1612 microcontroller, utilizes a series of timers to coordinate the rate of steps sent to the device. Once all the control signals are configured accordingly (ENABLEn = LO, SLEEPn = HI, RESETn = HI; DIR, USM0 and USM1 can be HI or LO depending on preferred mode of operation; SRn must be L, if external diodes are not populated), the motor is ready to be turned.
10 | Laser and Motor Drives |
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