Adapter

IoT with CAN bus

Printed circuit design for CAN node

(I have not tested the printed circuit board yet, because I have been too busy in other priority works)

Motivation

I want to develop very cheap and low power sensor/actuator network with electronic parts sold in Akizuki-Denshi, Tokyo.

Most of parts I use are DIP.

Architecture

Basic concept

I pursue seamless communications between CAN-bus and MQTT-bus:

Specification

The CAN node consists of one base board and one expansion board.

See this page for expansion boards: EXPANSION BOARDS.

CAN node base board

Circuit

PCB

BOM

CAN Standard Identifier format

This implementation supports CAN Standard Frame only (does not support Extended Frame). For home networking, 11bit Standard Identifier suffices.

=> FORMAT

"CAN adapter to UART" command list

This implementation supports CAN adapter functionality for PC and Android.

/// UART2CAN HELP (version 0.11  March 19, 2018) ///
[Set standard identifier] @i<standard identifier>
[Set output mode] {debug: @vd, verbose: @vv, normal: @vn}
[Enable operation mode] {loopback: @ol, normal: @on}
     with SID: @ols or @ons
[Set mask] @m<n><mask(SID10 ~ SID0)>
[Set filter] @f<n><filter(SID10 ~ SID0)>
[Set baud rate] @b<bpr>
[Abort all pending transmissions] @a
[Dump masks and filters] @F
[Dump registers] @D
[Send message] <message>
[Send message beginning with '@' character] @<@message>
[Receive message] <message> will be output
[Show this help]: @h

For example, to receive messages with SID 5, 10 and 15, set masks and filters to the CAN adapter as follows:

@m02047  --> RXM0 0b11111111111
@f05     --> RXF0 0b00000000101 (SID 5 message to RXB0)
@f110    --> RXF1 0b00000001010 (SID 10 message to RXB0)
@m12047  --> RXM1 0b11111111111
@f215    --> RXF2 0b00000001111 (SID 15 message to RXB1)

Development environment

• Microchip MPLAB-X IDE with MCC plugin.
• FreeCAD
• KiCAD
• 3D printer BIQU Magician
• RaspberryPi

Development plan and progress

M1 (completed on March 17, 2018)

• Purchased CAN adaptors from Amazon.
• Evaluate CAN ==> EVALUATION.
• Developed my original ASCII-based protocol over serial for MCP2515. The protocol is mainly for evaluating MCP2515.

At first, I use this universal board to make a prototype of the CAN adaptor:

I have finished the first prototype (Marth 25-27, 2018). I have made three boards, and it took eight hours.

M2 (completed on April 1, 2018)

3D printed enclosure for CAN node

• Purchase three pairs of MCP2515 and MCP2561 in Akihabara.
• Develop my original CAN adaptor board.
• Develop CAN-MQTT gateway on RasPi and OpenWrt.
• Develop a 3D-printed DIN rail enclosure for the board by using FreeCAD.
• Mount all of them on DIN rail (incl. RasPi).
• Add SLCAN that is ASCII-based protocol for SocketCAN.

M3

• Evaluate PIC16F18326 that is cheaper than PIC16F1825 and supports two MSSPs.
• Use KiCAD to redesign the circuit for PIC16F18326.
• Adopt moduler architecture: base board and sensor/actuator building blocks.
• Support sensors and actuators: doppler sensor, CdS, servo motor etc.

Reference

Datasheet (Microchip/NXP/Murata)

Microchip

• PIC16F1825
• MCP2515
• MCP2561
• MCP2515DM-BM

NXP

• TJA1050

Murata

• Ceralock