Hardware – STEP800

Hardware Overview

PCB size

120x80, 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 : step800_r1_0_0_dimension.pdf

System

The main components are as follows;

Components Manufacturer Model number
MCU Microchip ATSAMD21G18A
Ethernet Controller Wiznet W5500
Stepper Driver STMicroelectronics L6470
DC-DC Converter CUI P78E05-1000

Pin assignments

pin function etc
D0 Shift Register SCK
D1 NC Pad exposed in soldering side
D2 Shift Register MOSI
D3 Shift Register MISO
D4 SD_CS
D5 Shift Register ENABLE
D6 L6470 MISO
D7 NC Pad exposed in soldering side
D8 NC Pad exposed in soldering side
D9 NC Pad exposed in soldering side
D10 W5500_CS
D11 L6470 MOSI
D12 L6470 SCK
D13 L
D20/SDA NC Pad exposed in soldering side
D21/SCL NC Pad exposed in soldering side
D22/MISO W5500_MISO
D23/MOSI W5500_MOSI
D24/SCK W5500_SCK
D30 NC
D31 NC
D38 NC Pad exposed in soldering side
A0 L6470_CS
A1 NC Pad exposed in soldering side
A2 L6470_RESET
A3 W5500_RESET
A4 SD_DETECT
A5 Shift Register CS

Since the L6470_RESET and W5500_RESET are connected to the reset pins of L6470 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. R6 and R7 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 STEP800, different SPI ports are used for the L6470 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

L6470

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

Shift registers (DIP switch, brake output)

Pin Function SERCOM SERCOM Alt
D3 MISO - SERCOM2.1
D2 MOSI SERCOM2.2 -
D0 SCK - SERCOM2.3

L6470

Clock

A 16MHz crystal oscillator is connected to the OSCIN of Motor ID 1's L6470. From there, OSCOUT and OSCIN are daisy chained in order of IDs, so please set each L6470 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.

Unavailable L6470 features due to the hardware design

STCK

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

ADCIN

This is directly wired with GND and can not use.

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