PIC32CXBZ2_WBZ45x BLE UART MODBUS

"IOT Made Easy!"

Devices: | PIC32CXBZ2 | WBZ45x |
Features: | BLE | MODBUS |

⚠ Disclaimer

THE SOFTWARE ARE PROVIDED "AS IS" AND GIVE A PATH FOR SELF-SUPPORT AND SELF-MAINTENANCE. This repository contains example code intended to help accelerate client product development.

For additional Microchip repos, see: https://github.com/Microchip-MPLAB-Harmony

Checkout the Technical support portal to access our knowledge base, community forums or submit support ticket requests.

Contents

1. Introduction
2. Bill of materials
3. Hardware Setup
4. Software Setup
5. Harmony MCC Configuration
6. Board Programming
7. Run the demo
8. Related Applications

1. Introduction

This example application helps us to develop a request-response protocol using Modbus protocol. The WBZ451 Curiosity board acts as a client device or server device along with the RS485 2 click board. The RS485 communication with MODBUS protocol is mostly used over industrial sector for its highlighting features like balanced line communication, multi-drop facility, good noise immunity, and maximum data transmission speed. The MODBUS protocol with RS485 physical line makes transactions with multi-server easy and error free.

WBZ451 curiosity board as Client Device

The WBZ451 Curiosity board acts as Client Device or server device. The WBZ451 client device is connected to the WBZ451 server devices through RS485 2 Click board as shown below.​ The WBZ451 Client and server devices act as a Bluetooth(BLE) peripheral device, which helps to connect to the mobile phone through Microchip Bluetooth Data (MBD) mobile application. On the Client side, the MBD application (BLE Transparent UART) is used to send Modbus commands respective to the WBZ451 Server devices. On the Server side, it is used to display the Modbus data/logs to user via BLE.

MODBUS Doctor as Client Device

The Modbus Doctor acts as the Client Device and the WBZ451 Curiosity board acts as the Server Device. The client device (Modbus Doctor application) is connected to the WBZ451 interface via the RS485 2 Click board using an USB to RS485 converter.​ The WBZ451 Curiosity board also acts as a Bluetooth(BLE) peripheral device, which helps to connect to the mobile phone through Microchip Bluetooth Data (MBD) mobile application. MBD application (BLE Transparent UART) is used to display the Modbus data/logs to user via BLE.

Tip	For more details about the existing BLE applications, refer to the overview section of the PIC32CXBZ2 Application Developer's Guide

2. Bill of Materials

Tools	Quantity
PIC32CX-BZ2 and WBZ451 Curiosity Development Board	4
RS485 2 CLICK	4
USB to RS485 Converter	1

3. Hardware Setup

• Connect the RS485 2 click board with the WBZ451 Curiosity board using the connections described in the following table.

WBZ451	RS485 2 CLICK	Description	WBZ451	RS485 2 CLICK	Description
AN	NC	NC	PWM	RE	Receiver Enable
RST	NC	NC	INT	NC	NC
CS	DE	Driver Enable	RX	TX	USART TX
SCK	NC)	NC	TX	RX	USART RX
MISO	NC	NC	SCL	NC	NC
MOSI	NC	NC	SDA	NC	NC
3.3V	7(3.3V)	POWER SUPPLY	5V	NC	NC
GND	8(GND)	GROUND	GND	9(GND)	GROUND

To connect to the Modbus Doctor application

• Connect USB to RS485 converter to the system's USB port.
• Connect the A and B lines of the USB to RS485 converter to the corresponding A and B lines of the RS485 2 click which is interfaced with the WBZ451 Curiosity board. To implement a bus connection, connect the A and B lines of the USB to RS485 converter across all server devices as shown in the image below.

To connect to the WBZ451 Client device

• Connect the A and B lines of the RS485 2 click of the client device to the corresponding A and B lines of the server devices as shown below.

Note: Make sure to have common GND!

4. Software Setup

• MPLAB X IDE

  • Version: 6.05
  • XC32 Compiler v4.10
  • MPLAB® Code Configurator v5.1.17
  • PIC32CX-BZ_DFP v1.0.107
  • MCC Harmony
    • csp version: v3.14.0
    • core version: v3.11.1
    • CMSIS-FreeRTOS: v10.4.6
    • wireless_pic32cxbz_wbz: v1.1.0
    • wireless_ble: v1.0.0
    • dev_packs: v3.14.0
    • wolfssl version: v4.7.0
    • crypto version: v3.7.6

• Any Serial Terminal application like TERA TERM terminal application

• MODBUS DOCTOR

• MPLAB X IPE v6.05

5. Harmony MCC Configuration

Getting Started with Modbus Server application with the WBZ451 Curiosity Board

Tip	New users of MPLAB Code Configurator are recommended to go through the overview

Step 1 - Connect the WBZ451 Curiosity board to the device/system using a micro-USB cable.

Step 2 - The project graph of the application is shown below.

• From Device resources, go to Library->Harmony->Wireless->Drivers->BLE and select BLE Stack. Accept Dependencies or satisfiers, select "Yes" for automatic connections. Follow the configurations illustrated in the following figure. .

• From Device resources, go to Library->Harmony->Wireless->Drivers->BLE->Profiles and select TRANSPARENT Profile. Accept Dependencies or satisfiers. The configuration is depicted as follows.

• From Device resources, go to Library->Harmony->Wireless->Drivers->BLE-> Services and select TRANSPARENT Service. Accept Dependencies or satisfiers.

• From Device resources, go to Library->Harmony->Peripherals->SERCOM and selct SERCOM0. Right click on the "⬦" on UART and select STDIO. The configuration is depicted as follows.

• From Device resources, go to Library->Harmony->Peripherals->SERCOM and selct SERCOM1. The configuration is depicted as follows.

• Select Wolfcrypt library and make sure that "Support random number generation" box is unchecked as shown below.

• From Device resources, go to System services and select TIME. Right click on the "⬦" on the instance and select TC0.

• The SYSTEM configuration is depicted as follows.

• From project graph, go to Plugins->PIN configuration and configure as follows.

Step 4 - Generate the code.

Step 5 - From the downloaded .zip file copy the "modbus" and "port" folder by navigating to the following path: "../firmware/src/" and paste it under source files in your project folder (...\firmware\src).

Note	This application repository should be cloned/downloaded to perform the following steps.
Path	The application folder can be found in the following link

To add the folder to your MPLAB project

• In Projects section, right click on Source files to add the ".c" file and right click on Header files to add the ".h" file.
• Select "Add existing items from folder".
• Select Add and browse the location of the folder (...\firmware\src).
• Make sure the "Files of type" is "C Source files" while adding ".c" files and "Header files" while adding ".h" files.
• Select the folder and click "add".

Step 6 - In "app_user_edits.c", make sure the below code line is commented

• "#error User action required - manually edit files as described here".

Step 7 - Replace the app.c, app.h files and app_ble folder.

• Copy the "app.c" and "app.h" files by navigating to the following path: "../firmware/src/"
• Paste the files under source files in your project folder (...\firmware\src).
• Copy the "app_ble" folder by navigating to the following path: (...\firmware\src)
• Paste the files under the respective folder in your project folder .

Step 8 - Clean and build the project. To run the project, select "Make and program device" button.

MODBUS Doctor as Client Device

Step 9 - The Modbus Doctor settings are shown below.

• Mode: RTU
• Baud rate: 9600
• Parity: None
• Data bits: 8
• Stop bits: 1
• Com port: COM USB serial port(CH340)
• Once the settings are done, give "Connection". Once the connection is established, "Status: Connected" message will be shown.

Note	To connect the system to the USB to RS485 converter, install CH340 driver

Step 10 - The Modbus doctor initiates a request to write/read the server device's holding register and read the server device's input register.

• Holding register start address: 1 (Maximum Length:32)
• Input register start address: 1000(Maximum Length:64)
• The Server address, Register address, Length and Type of register should be updated in the below section in Modbus doctor application.

WBZ451 Curiosity board as Client Device

• In "app.h" file, uncomment the RTU_CLIENT macro and comment RTU_SERVER macro before programming to program a client device as shown below.

• Connect the WBZ451 Client device to a mobile phone using MBD app.
• After connecting, send the corresponding modbus data in the frame format given below to the WBZ451 Client device from MBD app.

Server Address	Function Code	Register Address	Data

• The scope of this application covers the below mentioned function codes.

Type	Mode	Function Code
Coil	Read	0x01
Coil	Write Single Coil	0x05
Coil	Write Multiple Coil	0x0F
Holding register	Read	0x03
Holding register	Write Single register	0x06
Holding register	Write Multiple register	0x10
Input register	Read	0x04

• The Client device calculates the CRC and initiates a request to write/read the server device's coil, holding register and read the server device's input register. 

Programming Server devices

• In "app.h" file, uncomment the RTU_SERVER macro value and comment the RTU_CLIENT macro before programming, to program a server device as shown below.

• In "app.c" file, change the SERVER_ADDRESS macro to a unique address before programming each server device as shown below.

• In "app_ble.c", change the last hex value of the "scanRspData[]" array to have a unique BLE scan response data.

6. Board Programming

Programming hex file:

Program the precompiled hex file using MPLAB X IPE

• The Precompiled hex file is given in the hex folder. Follow the steps provided in the link to program the precompiled hex file using MPLABX IPE to program the pre-compiled hex image.

Build and program the application using MPLAB X IDE

The application folder can be found by navigating to the following path:

• ".../PIC32CXBZ2_WBZ45x_BLE_UART_MODBUS/firmware/"

Follow the steps provided in the link to Build and program the application.

7. Run the demo

Modbus Doctor as Client device

• After programming the board, the expected application behavior is shown in the below video.

• In this application the Modbus doctor acts as the client device and initiates a request to write/read the registers in the server device. When a holding register is written in the server device and value is greater than zero it is indicated by the LED in the WBZ451 server device.
• The server device(BLE Peripheral) is connected to the MBD app(BLE Central) through BLE and the User LED indicates the BLE connection.
• Whenever the client initiates a request to the server device, the information in the data frame is sent to the MBD app(BLE Central device) from the server devices as shown in the above video.
• As shown in the video, by changing the server address the client can write/read the server device.

WBZ451 curiosity board as Client device

• After programming the board, the expected application behavior is shown in the below video.

• In this application the Modbus frame is sent to the Client device from the MBD app through BLE UART and the Client device adds the CRC and intiates a request to the server devices. The Modbus frame format and the register start address is illustrated below

• Holding register start address: 1 (Maximum Length:32)

• Input register start address: 1000(Maximum Length:64)

• Coil start address: 0 (Maximum Length:8)

• The Modbus frame format examples for the implemented functions in this application is shown in the table below.

• Coil Functions

Mode	Server Address	Function code	Register Address	Number of registers
Read	01	01	00 00	00 02

Mode	Server Address	Function code	Register Address	Data
Write Single Coil	01	05	00 00	00 FF

Mode	Server Address	Function code	Register Address	Number of registers	Data
Write Multiple Coil	01	01	00 00	00 02	01 00

• Holding register Functions

Mode	Server Address	Function code	Register Address	Number of registers
Read	01	03	00 00	00 02

Mode	Server Address	Function code	Register Address	Data
Write Single register	01	06	00 00	00 05

Mode	Server Address	Function code	Register Address	Number of registers	Byte Count	Data
Write Multiple register	01	10	00 00	00 02	04	00 05 00 02

• Input register Function

Mode	Server Address	Function code	Register Address	Number of registers
Read	01	04	03 E8	00 02

• The server devices sends the response for the request to the client device.

Note	For more details on the Modbus protocolplease go through this link

8. Related applications

• BLE Applications
• WBZ45x BLE UART WITH E-PAPER DISPLAY
• WBZ45x BLE Sensor Multi-Link Multi-Role Demo