#microstepping

We got our Allegro A4988 stepper driver breakout PCBs back and are ready to test them. First, we verified that STEP and DIR worked (yes!) and that the LEDs lit (yes, but we need to tweak the resistors to make the brightness even). Then we tried all of the stepper-settings, you can select 1, 4, 8, or 16-microsteps. All the sleep/reset/enable pins work. Finally, we checked the current limiting functionality with a potentiometer that can be twisted to select up to 2A current per coil. This directly affects the torque, so it's easy to test by verifying that we can stall the motor with hands or vise-grips. We'll order these with 2oz copper and get them into production next!

We've been testing the Trinamic/Maxim/Analog/WeylandYutani TMC2209 (https://www.digikey.com/short/8r5m38h8) breakout we designed, and it's working great - the step/dir interface plus the micro-step select allows a microcontroller to control a stepper with just GPIO and true-to-its-name it is a very silent stepper driver, much quieter than the A4988 (https://www.digikey.com/short/tfjt88dd)! There are a few different I/O pins on the TMC: Index tells you when a full step is completed, which is handy to know when you want to change stepper modes on the fly. Diag lets you know when a power or motor failure has occurred. It can also tell when the motor has stalled if it's configured to. Finally, and most interestingly, is the UART interface: this unidirectional pin lets you read and write configuration registers, set 1-128 microsteps, change current limiting, and detect stalls for 'auto homing'. So far, everything works; we're just going to swap the direction of the potentiometer so it twists clockwise to increase the current limit and book PCBs!

Read More: A4988 Current Limit

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