Advertisement
Warning: This carrier board uses low-ESR ceramic capacitors, which makes it
susceptible to destructive LC voltage spikes, especially when using power leads longer
than a few inches. Under the right conditions, these spikes can exceed the 35 V
maximum voltage rating for the A4988 and permanently damage the board, even
when the motor supply voltage is as low as 12 V. One way to protect the driver from
such spikes is to put a large (at least 47 µF) electrolytic capacitor across motor power
(VMOT) and ground somewhere close to the board.
MOTOR CONNECTIONS
Four, six, and eight-wire stepper motors can be driven by the A4988 if they are properly
connected;
a FAQ answer
explains the proper wirings in detail.
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 A4988 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.
The resolution (step size) selector inputs (MS1, MS2, and MS3) enable selection from
the five step resolutions according to the table below. MS1 and MS3 have internal
100kΩ pull-down resistors and MS2 has an internal 50kΩ pull-down resistor, so leaving
these three microstep selection pins disconnected results in full-step mode. For the
2
https://eckstein-shop.de/
Advertisement
