Texas Instruments Evaluation module for DRV8828 DRV8828EVM DRV8828EVM 데이터 시트
제품 코드
DRV8828EVM
Start Speed PPS
Start Speed PPS
Desired Speed PPS
Time
Base
Base
Accel Rate
UART Mode
Figure 8. Acceleration Profile
The following controls are available within the Motor Control Frame:
Start Speed PPS: Number of pulses per second (or Full Steps Per Second) at which the motor will rotate
at the beginning of operation. The SW will only allow a number as small as 61 PPS and can be taken to a
number as large as 65535 PPS.
at the beginning of operation. The SW will only allow a number as small as 61 PPS and can be taken to a
number as large as 65535 PPS.
Desired Speed PPS: Number of pulses per second (or Full Steps Per Second) at which we want the
motor to operate. The acceleration profile will start from the Start Speed PPS and increase stepping rate
until reaching the Desired Speed PPS. The SW will only allow a number as small as 61 PPS and can be
taken to a number as large as 65535 PPS.
motor to operate. The acceleration profile will start from the Start Speed PPS and increase stepping rate
until reaching the Desired Speed PPS. The SW will only allow a number as small as 61 PPS and can be
taken to a number as large as 65535 PPS.
Acceleration Rate (0-255): A number from 0 to 255 which acts as a stepping rate modifier to increase the
Start Speed PPS up to Desired Speed PPS. Each unit on the Acceleration Rate is equal to 250
Start Speed PPS up to Desired Speed PPS. Each unit on the Acceleration Rate is equal to 250
µ
s on the
internal timer clock.
Time Base (0-255 ms): Defines the amount of time in between stepping rate changes. The lower this
parameter, the faster the motor accelerates toward Desired Speed PPS stepping rate. Time Base is zero
based, so a value of 0 actually means 1-ms delay between stepping rate updates.
parameter, the faster the motor accelerates toward Desired Speed PPS stepping rate. Time Base is zero
based, so a value of 0 actually means 1-ms delay between stepping rate updates.
4.4.2
Direction Frame
Stepper motor direction of rotation can be controlled by specifying the desired direction on this frame.
Actual stepper rotation may be different depending on how the motor was wired to the EVM. If the
opposite direction is observed, simply reverse the motor connections and the motor should reverse the
direction of rotation as well.
Actual stepper rotation may be different depending on how the motor was wired to the EVM. If the
opposite direction is observed, simply reverse the motor connections and the motor should reverse the
direction of rotation as well.
Stepper direction of rotation is defined by selecting one of the radial buttons. Only one can be selected at
any given time. If the motor is not moving, changing the selection only applies to the next time the motor
starts moving. If the motor is rotating, change of direction will be observed instantaneously.
any given time. If the motor is not moving, changing the selection only applies to the next time the motor
starts moving. If the motor is rotating, change of direction will be observed instantaneously.
4.4.3
Decay Mode Frame
Current decay is of the utmost importantance especially during microstepping. Which decay mode is used
will play a vital role on the waveform generation due to two facts:
will play a vital role on the waveform generation due to two facts:
1. Slow decay is much more efficient than fast decay as the current ripple is minimized and average
current is higher. This allows for motor torque on a per step basis to be higher.
2. Slow decay does not allow the current to discharge the winding as fast as it charges it.
11
SLMU002
–
June 2011
DRV882x Evaluation Modules
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2011, Texas Instruments Incorporated