Day Six
Agenda
The Pololu A4988 module is a newer, compatible replacement for the A4983 module used in the stepper motor exercise. The A4988 is rated for an 8-35V motor supply voltage, so it is not compatible with the 2.7V stepper motors. The DRV8834 stepper motor driver is rated for a 2.5–10.8V motor supply voltage and should be compatible with the A4988 pinout. The pins should be soldered on the back side of the A4988 such that the driver chip is visible. This does mean that the pad silkscreen text is on the bottom and out of sight, but allows the chip to dissipate heat. If your module is *not* soldered in this orientation, please be especially careful when wiring the circuit. If you are unclear on the wiring of a stepper motor, use a DMM to measure the resistance between the wires. A bipolar stepper will have four wires, two per coil, and the low-resistance of the coil should be unambiguously measurable. The digital input using a switch needs a pullup resistor to function properly, otherwise the input pin is switched between an ambiguous ‘floating’ state and ground. The thermistors we have in stock are Vishay parts from SparkFun, who hosts a data sheet. |