Balance Bot

ESP-WROOM-32 Based Stepper Motor Controller

PCB integrating an ESP-WROOM-32 microcontroller with two A4988/DRV8825 stepper motor drivers.

This is a four layer PCB that I originally designed this for an ESP-32 controlled, NEMA17 powered robot. However it can also be useful for any other application requiring microcontroller control, stepper motors, and any form of SPI or I2C peripheral.

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Before connecting and driving the DRV8825, ensure that you set the current limit on both DRV8825/A4988 stepper drivers.

Features include:

• 'Battery drive'. Drive the board through a high voltage li-ion or LiPo battery, but enjoy three additional voltage rails:
  • 'Buck', aka the output from the onboard switching buck converter.
  • 5V rail through an onboard 5V LDO.
  • 3V3 rail through an onboard 3V3 LDO.
• USB-C fast USB programming and UART.
  • USB-C programming for easy cable manipulation, but only fast USB (ie USB 2.0 speed specification) is supported.
  • 'Auto program' (utilizing USB to place the MCU in program mode) is supported.
• Sleep, step, and direction pin connections for two DRV8825 stepper motor drivers. Control speed, direction, and sleep on/off (useful for low current operation) for two steppers individually.
  • This was designed with the thought that each controller would be handled via the ESP-32 MCPWM peripheral, but it's entirely feasible to control them through software if desired.
• Breakout for SPI.
• Breakout for I2C.
  • Three pins each for both I2C SDA and SCL.
• Voltage divider / voltmeter for 'battery' voltage.
• Breakouts for ESP-32 GPIOs 13, 25, 26, and 36.
  • These were unused in the original design, but can be handy for extra outputs (eg another SPI CS pin) or inputs.
• Pin headers for 1/8, 1/16, and 1/32nd microstepping.
  • Each stepper driver can be independently set for microstepping as required by your application.