2 Design Description

Figure 2-1 and Figure 2-2 show the block diagram and the PCB design of the motor module based on MSP430 and motor drivers to control the focus, tilt, and iris for an IP network camera.

The motor module operates from an external 5 V, 2 A power supply input. MSP430FR2155 communicates with the motor drivers to generate the control signals for their operation. Two DRV8428 drive stepper motors each for focus and tilt control and a DRV8837C drives a DC motor for iris control. TLV742P LDO generates 3.3 V supply from the 5 V input for logic operations of MSP430FR2155 and motor drivers.

Key features:

• Motor module is implemented using:
  • MSP430FR2155 microcontroller
  • DRV8837C brushed DC motor driver
  • two DRV8428 stepper motor drivers
  • 3.3-V power-supply (using TLV742P LDO)
• Configuration software to control the following:
  • Speed of rotation
  • Direction of rotation
  • Low-power state to reduce power consumption
  • Micro-stepping mode for stepper motors
  • Voltage for DC motor
  • Position using stepper motors
• Brushed DC motor driver DRV8837C for iris control:
  • 1 A max current
  • Integrated protection for over-current, short-circuit, under-voltage, and over-temperature
  The DRV8210P is a family of devices which is pin-compatible with DRV8837C. The DRV8210P supports 1.76 A peak current with ultra low-power sleep current of < 84.5 nA.
• Stepper motor driver DRV8428 for focus and tilt control:
  • 1 A max current
  • Integrated micro-stepping indexer,
  • Supports up to 1/256 micro step
  • Integrated current-sense to simplify design and improve efficiency
  • Small size 3.0 x 3.0mm QFN package
  • No charge pump caps required
  • Adjustable current regulation
  • Smart tune technology for ultra-smooth and quiet motion profile
  • Integrated protection for supply under-voltage, over-current, short-circuit, and over-temperature

Schematic, design files and software discussed in this document can be downloaded from the following URL: https://www.ti.com/lit/zip/slaae27.