Getting Started Guide: UART to Any Cloud Solution for Microchip PIC32MZ-W1 Curiosity/ WFI32E IOT Board.

Devices: | PIC32MZ-W1 | WFI32 | Trust&Go (ECC608) |

Introduction

⚠ 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

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Client are often challenged by fast and easy onboarding of Wifi product and to a given cloud. Microchip aims to make all these steps easy for the customer. This Solution allows easy connectivity to AWS, Azure and test.mosquitto.org with PIC32MZ-W1 Curiosity/ WFI32E IOT board, a powerfull MCU enabling the customer to create smart, connected and secure IoT solutions (Please visit www.microchip.com/wfi32 for more information including application notes, certifications, etc). Examples are provided in the github for PIC32MZ-W1 with Terminal over UART which can easily be used by replacing the terminal with 8/16/32-bit MCUs.

This page describes the UART to Any Cloud Solution for the PIC32MZ-W1 Curiosity/ WFI32E IOT board.

Features

1. Easy to learn ASCII AT commands for adding Wi-Fi and Cloud connectivity to any processor

2. Mutual authentication supported with AWS and Azure

3. Server authentication supported for test.mosquitto.org

4. Designed for WFI3E01PC and WFI32E01UC modules with integrated Trust&Go (TNG)

5. Single pre-built hex file supports all features for majority of use cases. No need to recompile image for different cloud vendors (single image supports connectivity with AWS / Azure / test.mosquitto.org)

6. Complete source to enable customization when required

7. Supports MQTT, Socket programming(TCP/ UDP), SNTP, TLS (v1.3/ v1.2), ICMP, IGMP, DNS, DHCP, Low Power, WPA3, Loading/ Reading Certificates via UART, WiFi Provisioning.

8. Features like OTA, Trust Flex, IPv6, mDNS planned for future releases.

Hardware Setup

Hardware Requirements

• PIC32MZ-W1 Curiosity or WFI32-IoT board
• Access Point with Internet

Software Requirements

• MPLAB X IDE (v6.0 or later)

• MPLAB XC32 (v3.01 or later)

• MPLAB Harmony 3

  • Note: The project was developed and tested using the MPLAB X v6.0, and MPLAB XC32 v3.01. Also, the above tools are not required when the solution’s pre-built hex file is used.

Solution block diagram

Solution Overview

The Solution code is written as a FreeRTOS based MPLAB Harmony3 solution that leverages the system service-based architecture of PIC32MZ W1. The Solution can connect to any of the three Clouds- AWS, Azure or test.mosquitto.org without the need for recompiling of the image.

Re-Flashing the device

In case you want to re-flash the device, perform the following steps:

1. Download and install MPLABX Integrated Programming Environment
2. Connect the power source selection jumper (J202) shunt in ‘PKOB-VIN’ position
3. Connect the Curiosity Board’s debug USB (J302) to your PC.
4. Open MPLABX IPE and select ‘PIC32MZ1025W104132’ device and ‘PKOB’ tool.
5. Download the latest FW image (hex file) from the releases tab and load it into the IPE ‘hex file’ section.
6. Click on the ‘connect’ and then the ‘program‘ buttons in the IPE and wait for device programming to complete.

Evaluating the Solution

Perform the following steps:

1. Connect the PIC32MZ-W1 Curiosity/ WFI32E IOT board to your PC/ Host MCU.

2. Open the Terminal application (Ex.:Tera term) on the computer.

3. Connect to the "USB to UART" COM port and configure the serial settings as follows:

   • Baud : 230400

   • Data : 8 Bits

   • Parity : None

   • Stop : 1 Bit

   • Flow Control : None

   Note: The UART used in this case is UART2.

4. All the configurations on the device will be done using AT Cmds via the UART. The details regarding the supported AT CMDs can be found in the document ATCommandReference.pdf in the "doc" folder

5. Configure the home AP credentials using the AT Cmds

   Example:

    AT+WSTAC=1,"DEMO_AP"
    AT+WSTAC=2,3
    AT+WSTAC=3,"password"
    AT+WSTAC=4,255
    AT+WSTAC=12,"pool.ntp.org"
    AT+WSTAC=13,1
    AT+WSTA=1
   

6. The device connects to the Wi-Fi and the IP address is assigned, and relevant AT Cmd response is sent to UART.

   Example:

   +WSTALU:"42:2C:62:CC:C0:0B",11
   +WSTAAIP:"192.168.159.108"
   +TIME:2,3864185092
   

7. Configure the device to connect to Cloud - in this case either of AWS or Azure or test.mosquitto.org

   Example:

   AT+MQTTC=1,"youramazonaws.com"
   AT+MQTTC=2,8883
   AT+MQTTC=3,"yourDeviceId"
   AT+MQTTCONN=1
   

   Note: One needs to register the device certificate with AWS and Azure portal in case the user wants to connect to either of these cloud vendors. More details in Cloud Setup Procedure document.

8. The device connects to the Cloud, and relevant AT Cmd response is sent to UART.

   Example:

    +MQTTCONNACK:0,0
    +MQTTCONN:1
   

Secure Provisioning & Transport Layer Security

The PIC32MZ-W1 Curiosity Boards kits are shipped with the WFI32 module variants that include an on-board Trust&Go secure element. Since Trust&Go devices are pre-provisioned, the customer does not need to programe the device certificate for each of his devices and the firmware can utilise the on-chip certificate to securely authenticate with AWS IoT Core/ Azure IoT Hub.

Known Issues and Limitations

1. Only 'Extended Deep Sleep' mode is supported currently in Low Power feature. 'Connected sleep' mode will be supported in future release.

2. Connectivity to Azure IoT Hub is currently not possible with domain name containing 'gateway' in it. The user would need to do a 'nslookup ' and check if the domain name contains 'gateway'. In case it does, the connectivity to the Azure server will not be possible.

3. Current drawn in 'Extended Deep Sleep' mode in Low Power is more than expected.