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F28075 ,DRV8842 Motor drive(PWM-ADC)

Other Parts Discussed in Thread: TMS320F28075, DRV8842

Hello ,

I am working on TMS320F28075 Microcontroller with DRV8842 Motor Driver IC.

In my application i will be getting an analog signal(voltage) which is given to an ADC(12bit) (ADCIN0 channel) of my controller.

Now i need to drive a DC motor Linearly according to the PWM duty cycle which i have generated(PWM of 50KHz). Max Period register value-65536.

At present i have captured the digital value in ADCResult Register and have put some compare values ranging from 0 to 4096 and according to those compare values i am varying the duty cycle(50%,75%,80%,100%).

I need the dc motor to rotate in a linear fashion from 0 to 100% duty cycle according to the input voltage(0v-3.3v).

How can i achieve this?

Regards,

Sanath Rai

  • Hi Sanath,

    Have you determined the minimum duty cycle required to operate the motor?
    Are you using the current regulation? If so, you may not achieve 100% duty cycle.
  • Hello Rick,

    The DC Motor is operating at minimum of 20%duty cycle.

    Yes i am using Current regulation.

    But i am planning to run the motor at maximum of above 90% duty cycle.

    Also i am planning to replace the DC motor with Solenoid (Hydraulic Proportional Valve)which i need to control solenoid current in a linear way.

    Regards,

    Sanath Rai

  • Hi Sanath,

    In theory, you can read your analog input from 0 to 100% in x% increments and drive the PWM inputs from 20% to 100% increasing by x*.8% increments. When approaching 100% PWM input, you may have to jump from some high duty cycle% (example 98%) to 100%.