Hardware – STEP400

Hardware Overview

PCB size

120x84, thickness = 1.6mm

There are five M3 mounting holes on each four corners and in the middle.

Long parts of the top and bottom in this picture are waste boards, and are removed after the production.

Actual size PDF : step400_r1_dimenstion.pdf

System

The main components are as follows;

Components Manufacturer Model number
MCU Microchip ATSAMD21G18A
Ethernet Controller Wiznet W5500
Stepper Driver STMicroelectronics PowerSTEP01
DC-DC Converter ROHM BD9G341AEFJ

Pin assignments

pin function etc
D0 DIPSW8
D1 Brake4
D2 DIPSW5
D3 DIPSW7
D4 SD_CS
D5 Brake3
D6 PowerSTEP01_MISO
D7 DIPSW1
D8 Brake2
D9 DIPSW6
D10 W5500_CS
D11 PowerSTEP01_MOSI
D12 PowerSTEP01_SCK
D13 L
D20/SDA NC Pad on PCB
D21/SCL NC Pad on PCB
D22/MISO W5500_MISO
D23/MOSI W5500_MOSI
D24/SCK W5500_SCK
D30 DIPSW2
D31 DIPSW4
D38 NC Pad on PCB
A0 PowerSTEP01_CS
A1 Brake1
A2 PowerSTEP01_RESET
A3 W5500_RESET
A4 SD_DETECT
A5 DIPSW3

Since the PowerSTEP01_RESET and W5500_RESET are connected to the reset pins of PowerSTEP01 and W5500 individually, be sure to set pinMode to OUTPUT and then set the state to HIGH.

Pads on PCB rear side

There are unassigned pins and power pads on the rear side of PCB. They are 2.54mm picth, so you can attach surface-mount pin-headers and IC sockets. R35 and R36 on the rear side can be used for the pull-up for the i2c pins(SDA, SDL). The chip size is 1608(0603).

Since these pins are not controlled from firmware, customizing firmware for your own purpose is necessary.

SPI assignment

For the STEP400, different SPI ports are used for the PowerSTEP01 and W5500 for the ease of firmware process. Here is a very informative guide to SPI allocation in ATSAMD21.

https://learn.adafruit.com/using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports

W5500

Pin Function SERCOM SERCOM Alt
D22/MISO MISO - SERCOM4.0
D23/MOSI MOSI - SERCOM4.2
D24/SCK SCK - SERCOM4.3

PowerSTEP01

Pin Function SERCOM SERCOM Alt
D6 MISO - SERCOM3.2
D11 MOSI - SERCOM3.0
D12 SCK - SERCOM3.3

PowerSTEP01

Clock

A 16MHz crystal oscillator is connected to the OSCIN of Motor ID 1's PowerSTEP01. From there, OSCOUT and OSCIN are daisy chained in order of IDs, so please set each PowerSTEP01 to "External 16MHz input, Inverted output(EXT_16MHZ_OSCOUT_INVERT)". If the internal clock is used, the movement may shift gradually during constant speed operation.

Unavaiable PowerSTEP01 features due to the hardware limitations

STCK

Since it is not wired, Step Clock operation is not possible.

ADCIN

This is used for the limit sensor inputs, therefore not used for the original supply voltage compensation featue. Be sure to disable UVLO_ADC, which will raise the alarm based on the value of the ADC input.

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