Our N2K-BT gateway functions as a NMEA 2000 to Bluetooth data scanner for any host device with a Bluetooth or BLE (Bluetooth Low Energy) port, such as PCs, phones, or tablets. Therefore, it supports operating systems such as Windows, Linux, iOS, Android, and more. In addition, the wireless communication protocol employs easy-to-read and easy-to-process ASCII data strings, making it easy for iOS and Android developers to interpret the data stream. 

Hardware

The data scanner hardware utilizes the ESP32 processor with Bluetooth, BLE, and WiFi capabilities and a CAN Bus port with a transceiver. 

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. 

The module accepts an external power supply between 7 and 36 VDC with reverse polarity protection. It operates safely within a temperature range of -40C to +85C. The NMEA 2000 port is accessible via a Micro-C connector (M12 5Pin Male Socket). 

Software

It is important to emphasize that the module merely transmits processed CAN data frames as they appear in the network, i.e., it does not support NMEA 2000 protocol management features. 

However, it allows the user to monitor and filter PGNs needed for their application.

The ASCII data string includes: 

• Data Page 
• PGN 
• Priority 
• Destination Address 
• Source Address 
• DLC (Data Length Code)
• Data 
• Checksum

Bluetooth Test

We used a Windows PC with terminal software to test the Bluetooth communication. The terminal software connects to the Bluetooth COM port. Our test device connects to a NMEA 2000 simulation network based on our SAE J1939 to USB Gateway (NMEA 2000 is a derivative of SAE J1939). In addition, we monitor the CAN Bus data traffic with a separate CAN Bus monitor system.

The below screen shot shows the received data traffic on the Windows PC:

However, let's have a look at a single data frame. In the following example, we are using PGN 65336 (0xFF38, broadcast message) with a source address of 34 (0x22) and priority = 6.

The BT scanner converts the CAN data into the ASCCI string as shown below:

0 - Data Page

FF38 - PGN

6 - Priority

FF - Destination Address (Global Address)

20 - Source Address

8 - Data Length

8877665544332211 - Data

67 - Checksum

We are working on a documentation of our testing with an Android phone, and we will follow up with another post.

BLE (Bluetooth Low Energy)

BLE is a requirement for communication with Apple's iOS. At this point, we have a working version and will also introduce it in another post. The testing environment is, of course, different, i.e., we are using an iMac, and an iPhone in combination with the nRF Connect app.

Status and Availability

Officially, the N2K-BT module is still under development, and we target a release in October 2022. We consider the software development as finished regarding the mere data scanning capabilities, but we are considering, among others, the implementation of PGN filters to reduce the wireless data traffic.

Please feel free to contact us in case you need further information. We are also available to develop customized hardware and software to meet your requirements.

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