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Power connections
The driver requires a logic supply voltage (3 –5 V) to be connected across the VCC and
GND pins and a motor supply voltage of 1.8 V to 10 V to be connected across VIN and
GND. These supplies should have appropriate decoupling capacitors close to the board,
and they should be capable of delivering the expected currents (peaks up to 3 A for the
motor supply).
Motor connections
The STSPIN220 is intended to control a single bipolar stepper motor. The two sides of
one coil should be connected across OUTA1 and OUTA2, and the two sides of the other
coil should be connected across OUTB1 and OUTB2.
Warning: Connecting or disconnecting a stepper motor while the driver is powered can
destroy the driver. (More generally, rewiring anything while it is powered is asking for
trouble.)
Step (and microstep) size
Stepper motors typically have a step size specification (e.g. 1.8° or 200 steps per
revolution), which applies to full steps. A microstepping driver such as the STSPIN220
allows higher resolutions by allowing intermediate step locations, which are achieved
by energizing the coils with intermediate current levels. For instance, driving a motor
in quarter-step mode will give the 200-step-per-revolution motor 800 microsteps per
revolution by using four different current levels.
Unlike our other stepper motor drivers, some of the resolution (step size) selector
inputs share pins with the STEP/STCK and DIR pins, and the values of the inputs are
latched at power-up or when standby mode is released. After this, the values on the
inputs do not affect the microstep mode, and the MODE3 and MODE4 inputs start
operating as step and direction controls. The only exception is the case where MODE1
