Stepper 15 Click, uses the DRV8889A, an integrated motor-driver solution for bipolar stepper motors from Texas Instruments. The DRV8889A integrates two N-channel power MOSFET H-bridges (disabled by default after Power-Up), integrated current sense and regulation circuitry, and a microstepping indexer. It can be powered with a supply voltage from 4.5 to 45V, providing an output current up to 2.4A peak, 1.5A full-scale, or 1.1A RMS.

The DRV8889A uses an integrated current-sense architecture which eliminates the need for two external power sense resistors. This architecture removes the power dissipated in the sense resistors using a current mirror approach and using the internal power MOSFETs for current sensing. It also includes an integrated torque DAC that allows the controller to scale the output current through a full-duplex, 4-wire synchronous SPI interface without needing to scale the voltage reference. The torque DAC allows the controller to save system power by decreasing the motor current consumption when high output torque is not required.

A simple STEP/DIR interface allows an external MCU to manage the direction and step rate of the stepper motor. The internal indexer can execute high-accuracy microstepping without requiring the MCU to handle the winding current level. The indexer is capable of the whole step, half step, and 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, and 1/256 microstepping. Also, a noncircular half stepping mode is available for increased torque output at higher motor RPM in addition to a standard half stepping mode.

Unlike the STEP pin controlled by the PWM pin from the mikroBUS™ socket, other pins from the DRV8889A such as Sleep mode selection, fault indicator, direction selection, and device disable pin are controlled through a well-known 8bit I/O expander, the PCA9538 from NXP Semiconductor using the standard I2C 2-Wire interface with a maximum frequency of 400kHz. The PCA9538 also uses RST and INT pins from the mikroBUS™ socket as a hardware reset and interrupt function.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. It allows for both 3.3V and 5V capable MCUs to use the communication lines properly. Additionally, there is a possibility for stepper motor driver power supply selection via jumper labeled as VM SEL to supply the DRV8889A from an external input terminal in the range from 4.5 to 45V or with a 5V from mikroBUS™ power rail