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CAN Bus Development with ESP32-WROOM32 Development Board

Posted by Wilfried Voss on Dec 8th 2021

This post will demonstrate how to add a CAN Bus port to the ESP32-WROOM32 development board, i.e., regarding hardware and software.

Download this post as PDF...

As a matter of fact, we already offer a hardware utilizing the ESP32 processor and an onboard CAN Bus transceiver as shown in the image to the left.

The ESP32 WiFi, Bluetooth Classic, BLE, CAN Bus Module comes with an onboard ESP32 WROOM-32 WiFi, Bluetooth Classic, BLE Module, and a CAN Bus port with a transceiver. Also, onboard is an RGB LED, IO pins on a 0.1" pad.

The programming is accomplished through the popular Arduino IDE connected to the USB-to-Serial converter with USB-C connector, automatic bootloader and reset.

However, if you don’t need the supported 12 VDC power connection and extended temperature range (specifically suited for automotive and industrial applications) but are satisfied with the power supplied per USB port, you may prefer the lower-priced application as described here.

For this project we are using:

The ESP32 is a series of low-cost, low-power system-on-chip microcontrollers with integrated Wi-Fi and dual-mode Bluetooth. The ESP32 series employs a Tensilica Xtensa LX6 microprocessor in both dual-core and single-core variations and includes built-in antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power management modules. It is a successor to the ESP8266 SoC.

The ESP32 DevKit Board contains the ESP-WROOM-32 as the main module and some additional hardware to easily program ESP32 and connect with the GPIO Pins.

ESP32 Features

Single or Dual-Core 32-bit LX6 Microprocessor with clock frequency up to 240 MHz.
520 KB of SRAM, 448 KB of ROM and 16 KB of RTC SRAM.
Supports 802.11 b/g/n Wi-Fi connectivity with speeds up to 150 Mbps.
Support for both Classic Bluetooth v4.2 and BLE specifications.
34 Programmable GPIOs.
Up to 18 channels of 12-bit SAR ADC and 2 channels of 8-bit DAC
Serial Connectivity include 4 x SPI, 2 x I2C, 2 x I2S, 3 x UART.
Ethernet MAC for physical LAN Communication (requires external PHY).
1 Host controller for SD/SDIO/MMC and 1 Slave controller for SDIO/SPI.
Motor PWM and up to 16-channels of LED PWM.
Secure Boot and Flash Encryption.
Cryptographic Hardware Acceleration for AES, Hash (SHA-2), RSA, ECC and RNG.

ESP32 Board Components

ESP-WROOM-32 Module
Two rows of IO Pins (with 15 pins on each side)
CP2012 USB – UART Bridge IC
Micro–USB Connector (for power and programming)
AMS1117 3.3V Regulator IC
Enable Button (for Reset)
Boot Button (for flashing)
Power LED (Red)
Some passive components

CAN Bus Connection

The ESP32 integrates a CAN Bus controller compatible with the NXP SJA1000. Thus, it is CAN 2.0B specification compliant.

As with the SJA1000, the ESP32 CAN Bus controller provides only the data link layer and the physical layer signaling sublayer. Therefore, an external transceiver module is required, which converts the CAN-RX and CAN-TX signals of the ESP32 into CAN_H and CAN_L bus signals. The transceiver, such as the MCP2551 or SN65HVD23X, provides compatibility with ISO 11898-2.

Note:The SJA1000 does not support CAN-FD and is not CAN-FD tolerant.

CAN_TXD = ESP32 – IO25
CAN_RXD = ESP32 – IO26

For better resolution, download the PDF file.

CAN Bus Programming

For the CAN Bus programming we used the resources as shown in the following. We didn’t deem it necessary to repeat information in this post that is already sufficiently provided.

However, please be aware of some of the internal CAN controller's restrictions, namely the limited range of supported CAN baud rates:

5 KBPS - Not Supported
10 KBPS - Not Supported
20 KBPS - Not Supported
31K25BPS - Not Supported
33 KBPS - Not Supported
40 KBPS - Not Supported
50 KBPS
80 KBPS - Not Supported
100 KBPS
125 KBPS (Default)
200 KBPS - Not Supported
250 KBPS
500 KBPS
1000 KBPS

The CAN Bus driver source code plus code samples can be found at:

sandeepmistry/arduino-CAN: An Arduino library for sending and receiving data using CAN bus. (github.com)

For instructions on how to program the ESP32 using the Arduino IDE, see:

How to Program ESP32 with Arduino IDE? (electronicshub.org)

Further Development Resources

Internet of Things Projects with ESP32: Build exciting and powerful IoT projects

The ESP32, a low-cost MCU with integrated Wi-Fi and BLE capabilities, comes with a variety of modules and development boards for building IoT applications efficiently. Wi-Fi and BLE are standard network stacks for Internet-of-Things applications providing cost-effective solutions for your business and project requirements.

This book is a fundamental guide for developing ESP32 programs and starts by explaining GPIO (General Purpose I/O) programming with sensor devices. The reader gets up to speed with ESP32 development through several IoT projects such as weather stations, sensor loggers, smart homes, Wi-Fi cams, and Wi-Fi wardriving. The reader learns how to use ESP32 boards to facilitate interactions between mobile applications and cloud servers, such as AWS.
By the end of this book, you'll have learned how to control a range of IoT projects using the ESP32 chip.

More Information...