sparkfun AST-CAN485 Technical document

AST-CAN485 WiFi Shield Hookup Guide
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Introduction
What would make the AST-CAN485 even better? WiFi! In order to further the communications
capabilities of the CAN485, we present the AST-CAN485 Wifi Shield. The shield is based on the
Sparkfun ESP8266 thing and allows for a CAN485 module to communicate over Wifi.
SparkFun AST-CAN485 WiFi Shield
WRL-14597
…
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AST-CAN485 WiFi Shield Hookup Guide Wishlist SparkFun Wish List
Required Materials
To follow along with this tutorial, you will need the following materials. You may not need everything
though depending on what you have. Add it to your cart, read through the guide, and adjust the cart as
necessary.
SparkFun AST-CAN485 WiFi Shield
WRL-14597
SparkFun FTDI Basic Breakout - 3.3V
DEV-09873
This is the newest revision of our [FTDI Basic](http://www.sparkfun.com/commerce/product_info.php?…
SparkFun FTDI Basic Breakout - 5V
DEV-09716
This is the newest revision of our [FTDI Basic](https://www.sparkfun.com/products/retired/9115). We n…
SparkFun USB Mini-B Cable - 6 Foot
CAB-11301
This is a USB 2.0 type A to Mini-B 5-pin cable. You know, the mini-B connector that usually comes wit…
Break Away Headers - Straight
PRT-00116
A
row of headers - break to fit. 40 pins that can be cut to any size. Used with custom PCBs or general…
SparkFun AST-CAN485 Dev Board
DEV-14483
Tools
Depending on your setup, you will need a soldering iron, solder, and general soldering accessories to
solder pins to the AST-CAN485. You will also need a flat head and wire strippers to connect wires to
the screw terminals.
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Suggested Reading
We recommend checking out the AST-CAN485 Hookup Guide to get started with the board. Depending
on your setup, you may need to install custom libraries and board add-ons.
Soldering Iron - 60W (Adjustable
Temperature)
TOL-14456
Solder Lead Free - 15-gram Tube
TOL-09163
Pocket Screwdriver Set
TOL-12891
Wire Strippers - 20-30AWG
TOL-14763
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If you aren’t familiar with the following concepts, we also recommend checking out these tutorials
before continuing.
A
ST-CAN485 Hookup Guide
MARCH 1, 201
8
The AST CAN485 is a miniature Arduino in the compact form factor of the
ProMini. In addition to all the usual features it has on-board CAN and RS485
ports enabling quick and easy interfacing to a multitude of industrial devices.
Working with Wire
How to strip, crimp, and work with wire.
ESP8266 Thing Development Board
Hookup Guide
A
n overview of SparkFun's ESP8266 Thing
Development Board - a development board for the
Internet of Things.
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Hardware Overview
Input Power
The AST-CAN485 WiFi Shield provides screw terminals for your power, RS-485 signals, and CAN bus
signals, presoldered to the board for fast and secure connections.
The input voltage range is 7-24VDC. The input voltage is regulated down to 5V to supply power the
CAN485 board, as well as 3.3V to power the ESP8266.
Three Quick Tips About Using U.FL
Quick tips regarding how to connect, protect, and
disconnect U.FL connectors.
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ESP8266
Based on the SparkFun ESP8266 Thing, you can use either the PCB trace antenna, or the U.FL
connector if housed in a metal enclosure.
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Programming Switc
h
Because the UARTs are connected together for the CAN485 board and the ESP8266, a switch is used
to separate the RX and TX signals. When programing either the ESP8266 or CAN485 board, move the
switch over to the PROG position, and after the upload is complete, toggle the switch to the RUN
position.
Speaking of programming, the ESP8266 runs off of 3.3V logic, so to program the ESP8266, a 3.3V
USB to UART bridge is used.
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AST-CAN485 Serial Port
A header breaks out the Software Serial port used by the CAN485. This can be used as a debugging
serial port or to connect other devices.
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Pinouts
The pinout for the WiFi Shield is shown below:
Image courtesy of AST
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⚡Warning! This board has pins that operate at 24V as well as pins that operate at 5V and 3.3V.
Care should be taken during wiring as 24V has the potential to do significant damage to 5V and
3.3V circuits.
Schematic
The schematic below shows the layout of the interconnects between an inserted CAN485 module and
the integrated ESP module.
Image courtesy of AST
The primary interface between the CAN485 and the ESP8266 is a serial port. It operates on hardware
serial port 0 on the CAN485 rather than the traditional Software Serial port. The reason for this is that it
enables higher speed communications between the two devices. The trade-off of this feature is that it
uses the main serial port, which is also used to program the CAN485 and is broken out on its FTDI
header. This means that in order to program the CAN485 module, while it is inserted, the serial port
must be disconnected. For this reason, the mode selection switch was added which allows for the rx
and tx lines to be disconnected. In a similar way, the same serial port is used to both program the
ESP8266 and communicate with the CAN485. The mode selection switch also enables the ESP to be
programmed by disconnecting it from the CAN485.
Hardware Hookup
The AST-CAN485 WiFi Shield comes with headers pre-soldered to the board. Insert the CAN485 as
shown with the CAN485's FTDI header close to the ESP8266.
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Powering The Board
The Shield can be powered through the screw terminals. While the power input is intended to be
supplied with 24V, an input voltage of 7-24V may be used.
An integrated power supply regulates the 24V input power down to 5V which is used to provide power
to the inserted CAN485 board. This is further regulated down to 3.3V to power the ESP module.
It is also possible to power the board using the raw input pin of the CAN485 module. However, use of
an external 24V supply is recommended and is the intended use case.
Image courtesy of AST
⚡Warning! This board has pins that operate at 24V as well as pins that operate at 5V and 3.3V.
Care should be taken during wiring as 24V has the potential to do significant damage to 5V and
3.3V circuits.
Software Setup and Programming
Note: This example assumes you are using the latest version of the Arduino IDE on your desktop.
If this is your first time using Arduino, please review our tutorial on installing the Arduino IDE. If
you have not previously installed an Arduino library or board add-on, please check out our library
installation guide and instructions to install the AST-CAN485 board add-on files.
The Programming Mode Selection Switch
The ESP and CAN485 modules are connected using a hardware serial port. The same port is used to
program either of the devices. It is therefore necessary to disconnect the serial port in order to program
either of the devices. A selector switch is provided in order to make this possible.
If the selector switch is set to RUN, the ESP and CAN485 are connected via a serial port. If the switch
is set to PROG, the serial port is disconnected and the devices may be programmed.
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Setup Arduino For ESP Programming
There are many options for programming ESP8266 based devices. The approach recommended by
this guide is to make use of the ESP8266 Arduino Addon which has been developed by the ESP
community. The Addon can be downloaded via the GitHub Repository or by clicking the button below.
ESP8266 GITHUB REPOSITORY (ZIP)
This implementation is based on the ESP8266 Thing and the same setup instructions may be used. For
more information, refer to the ESP8266 Thing Hookup Guide.
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If you have not previously installed an Arduino library, please check out our installation guide.
Programming the ESP
The following process is followed in order to program the ESP module:
• Switch the mode selection switch to PROG.
• Insert a 3.3V FTDI into the FTDI header.
• Hold down the ESP programming button and upload a sketch.
• Return the mode selection switch to RUN to reconnect the devices.
ESP8266 Thing Development Board Hookup Guide
NOVEMBER 5, 201
5
A
n overview of SparkFun's ESP8266 Thing Development Board - a development
board for the Internet of Things.
Installing an Arduino Library
JANUARY 11, 201
3
How do I install a custom Arduino library? It's easy! This tutorial will go over how
to install an Arduino library using the Arduino Library Manager. For libraries not
linked with the Arduino IDE, we will also go over manually installing an Arduino
library.
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Programming the ESP Module
Image courtesy of AST
Programming the CAN485
The following process is followed in order to program the CAN485 module:
• Switch the mode selection switch to PROG.
• Connect a 5V FTDI to the FTDI header on the CAN485 module.
• Upload a sketch
• Return the mode selection switch to RUN to reconnect the devices.
Programming Inserted CAN485 Module
Image courtesy of AST
Examples
The WiFi Shield GitHub Repository includes a few examples which demonstrate the use of the board.
After downloading the repository, open up one the examples in the Arduino IDE. Select the CAN485 as
the board, the COM port that it enumerated on, and hit upload to test.
Basic Serial Example
This example demonstrates serial communication between and inserted CAN485 and the on board
ESP8266. Each device has a built in LED which is controlled by the other device over the serial port.
Operation is as follows:
• The CAN485 sends a command to the ESP every 100 ms.
• The ESP sets its LED on or off depending on the command.
• The ESP sends the same command back to the CAN485.
• The CAN485 sets its LED depending on the command received by the ESP.
In addition to the examples in the WiFi Shield GitHub Repository, there are a number of examples
using the ESP8266 in the ESP Arduino Library. These are accessible in the Arduino IDE under
File>Examples. Examples may also be found in the ESP Github Community Forum.
Resources and Going Further
For more information, check out the resources below:
AST-CAN485 WiFi Shield
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• GitHub Product Repo
•Schematic(PDF)
• Eagle Files (ZIP)
• SFE Product Showcase
AST-CAN485 Dev Board
• AST GitHub Repo
◦CAN485 Product Repo
◦AST CAN Library
◦AST RS485 Library
◦AST AltSoftSerial
◦Arduino Boards Packages
Need some inspiration for your next project? Check out some of these related tutorials:
Or dig in further with According to Pete for more information about RS485.
OBD II UART Hookup Guide
How to start working with the OBD-II Uart board.
CAN-BUS Shield Hookup Guide
A
basic introduction to working with the CAN-Bus
shield.
Getting Started with OBD-II
A
general guide to the OBD-II protocols used fo
r
communication in automotive and industrial
applications.
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According to Pete: How RS-485 Works
APRIL 2, 2018
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https://learn.sparkfun.com/tutorials/ast-can48
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