The Internet of Things (IoT) application has attracted a lot of attention due to its powerfulness to build a digital cyber world with meaningful information.Mainly, IoT’s devices are characterized by an (i)small size, (ii) short memory, and (iii)low consumption energy. Towards this end, reduced-memory and efficient embedded real-time operating systems (RTOS) are required to process data acquired by such devices. Primarily, RTOS is designed to support IoT devices in diverse applications andoperational requirements on time. FreeRTOS is known as one of the most utilized RTOS in practice. This is becauseit supports numerous processor architectures and its possession by Amazon has driven increased investment in engineering. Nonetheless, FreeRTOS connectivity is limited to Wi-Fi, Ethernet, or Amazon Web Services (AWS)-IoT Core via a mobile device using Bluetooth Low Energy connectivity. This rends the communication’s coverage very short, especially when connecting to the application and network remotely is needed. Motivating by the above, we aim to add new functionality in FreeRTOS AWS allow-ing to support a cellular Service in module Quectel BG96 (e.g. Narrowband (NB)-IoT,2G) able to connect the device to the internet.

To install our project you will need:

• B-L475E-IOT01A2 STM32 Discovery kit IoT node connected to BG96 (LTE Cat M1/Cat NB1/EGPRS modem) through X-NUCLEO-STMODA1 expansion board.

Figure 1. Material Used

• STM32 ST-LINK utility from https://www.st.com/en/development-tools/stsw-link004.html

• Clone this repository

• Upgrade the modem BG96 to the latest firmware. (https://github.com/1NCE-GmbH/blueprint-freertos/tree/master/Utilities/Modem_FW) Note: Download the modem FW flasher tool (QFlash) from this url: https://github.com/1NCE-GmbH/blueprint-freertos/tree/master/Utilities/Modem_FW this tools taked from quectel from the web site listed in the official documentation.

• Import the project.

Screenshot 1. Import project

Screenshot 2. Help

Screenshot 3. Help2

//  #define CONFIG_TROUBLESHOOTING_DEMO_ENABLED
//#define CONFIG_UDP_DEMO_ENABLED
//#define CONFIG_COAP_DEMO_ENABLED
#define CONFIG_CORE_MQTT_MUTUAL_AUTH_DEMO_ENABLED

• Edit the following parameter in config_files/nce_demo_config.h :

/* MQTT Configuration */ 
#define ONBOARDING_ENDPOINT  "device.connectivity-suite.cloud"
#define PUBLISH_PAYLOAD_FORMAT                   "Welcome to 1NCE's Solution"
#define SUB_TOPIC "/1nce_test"
#define clientcredentialMQTT_BROKER_PORT 8883
#define democonfigRANGE_SIZE 500 //(you can add the range request or comment this line )

• debug the code.

Screenshot 4. Debug

• Open a console on MPU Serial Device.

Our goal is to automate device onboarding and make the connection more simple, easy and fast to establish within Amazon FreeRTOS.

To automatize the process of establishing a connection with the AWS cloud we need to:

• Get the certificate from 1NCE API.

• Prepare the certificate.

• Send the certificate to the modem.

We send an HTTPS request to our API to get the response :

char send_packet[] = "GET /device-api/onboarding HTTP/1.1\r\n"
          "Host: device.connectivity-suite.cloud\r\n"
          "Accept: text/csv\r\n\r\n";
int32_t SendVal = SOCKETS_Send(cert_socket, &send_packet,strlen(send_packet), NULL);

In the BG96 we receive the response splitted in partitions with size of 1500 bytes (in case you did not precise the Range in nce_demo_config) :

rec = SOCKETS_Recv(cert_socket, (com_char_t*) &PART[0],
    (int32_t) sizeof(PART),
    NULL);

For the preparation of the certificate, we need to merge all the response in one variable because the response comes in multiple partitions.

for the memory optimisation, we use just one variable when we receive the response we add to the variable.

char *token = strtok(all, ",");
// in the token we have the first element which is the iccid
while (token != NULL) {

    token = strtok(NULL, ",");
    //we have the second element
}

Replace \n in response with the breakline. (before send it to the modem)

memcpy(PART, str_replace(PART, rep, w), strlen(PART));

char root_cmd[30] = "AT+QFUPL=\"root.pem\",";
sprintf(root_cmd, "%s%d,60", root_cmd, root_size);
root_cmd_size = strlen(root_cmd);
cs_status = osCDS_direct_cmd(&crt_command_root,CST_cellular_direct_cmd_callback);
retval = sendToIPC(0, (uint8_t*) &PART[0], root_size);

open a Secure Socket for BG96 we need to send some AT commands :

In order to set up the MQTT client to use a secure connection.

• AT+QSSLCFG= "clientkey",,<client_key_path>

• AT+QSSLCFG= "seclevel",, :Configure the authentication mode for the specified SSL context.

• AT+QSSLCFG="sslversion",,, :Configure the SSL version for the specified SSL context

• AT+QSSLCFG="ciphersuite",, :Configure the SSL cipher suites for the specified SSL context.

• AT+QSSLCLOSE= to make sure the socket which we need to open is close.

To facilitate the understanding of our solution we try to give you some scenario.

Figure 2. Mqtt Scenario

1NCE’s AWS FreeRTOS Version allows customers to communicate with the IoT core with MQTT (by default ) or UDP and use of all features as part of the 1NCE IoT Connectivity Suite.

1. • Go to config_files/aws_demo_config.h --> choose the Demo you want to unable (UDP Example)

//  #define CONFIG_TROUBLESHOOTING_DEMO_ENABLED
#define CONFIG_UDP_DEMO_ENABLED
//#define CONFIG_COAP_DEMO_ENABLED
//#define CONFIG_CORE_MQTT_MUTUAL_AUTH_DEMO_ENABLED

2. The onboarding script configuration can be found in blueprint-freertos\vendors\st\boards\stm32l475_discovery\aws_demos\config_files\nce_demo_config.h in the root folder of the blueprint or /aws_demos/config_files/nce_demo_config.h in IDE.

/* UDP Configuration */ 
//URL used to perform the onboarding call
#define UDP_ENDPOINT "udp.connectivity-suite.cloud"
//port to connect to the UDP endpoint.
#define UDP_PORT 4445
//the message you want to publish in IoT Core
#define PUBLISH_PAYLOAD_FORMAT                   "Welcome to 1NCE's Solution"

The bluePrint consists of an example to publish a message in IoT Core with UDP. In IoT Core we subscribe in /messages and we run our solution :

Figure 3. UDP Demo

In this Section our SDK following steps are executed:

• Register to the Network.
• Perform a DNS Resolution.
• Create a socket and connect to Server
• Create Confirmable CoAP POST with Quiry option
• Create Client Interaction and analyse the response (ACK)
• Valid the response.

The code by default work with MQTT if you want to use our CoAP Solution you need to add : /aws_demos/config_files/demo_config.h

#define COAP_ENDPOINT "coap.connectivity-suite.cloud"
#define configCOAP_PORT    5683
#define configCOAP_URI_PATH    "t=<quiry_path>"
#define PUBLISH_PAYLOAD_FORMAT                   "your text"

Figure 4. COAP Demo

For the DTLS Support the default Port is 5684 and define the DTLS_Demo as aditional define

#define ENABLE_DTLS
#define COAP_ENDPOINT "coap.connectivity-suite.cloud"
#define configCOAP_PORT    5684
#define configCOAP_URI_PATH    "t=<quiry_path>"
#define PUBLISH_PAYLOAD_FORMAT                   "your text"

The CoAP DTLS performs 3 main tasks :

• Send the Onboarding Request
• Get the Response
• Process the Response and give the DTLS identity and PSK to the application code.

Figure 5. DTLS Flow

Figure 5. DTLS Demo

This feature is limited to Users and Accounts who have already accepted our Connectivity Suite Addendum to the 1NCE T&Cs. It is a one-time action per 1NCE Customer Account. Please log into the 1NCE Customer Portal as Owner or Admin, navigate to the Connectivity Suite, and accept the Terms. If you don't see anything to accept and get directly to the Dashboard of the Connectivity Suite, you are ready to go!

N.B: The SMS and Data Consumed for the Troubleshooting is counted against the Customers own Volume of the SIM Card.

This initial version's main target is to allow customers to connect their Things and automate the network debugging faster and more reliably. This will also reduce the workload on our Customer facing support teams and will also allow us to focus on further common issues.

1. Go to config_files/nce_demo_config.h --> enable the flag TROUBLESHOOTING (Troubleshooting Example with/without DTLS in primary Flow and SMS as alternative)

/* COAP Configuration with/without DTLS */
#define ENABLE_DTLS //if you want to use the DTLS support
#define COAP_ENDPOINT "coap.connectivity-suite.cloud"
#define configCOAP_PORT    5684 // Prot with DTLS if you want to use Coap without DTLS use the port 5683
#define configCOAP_URI_QUERY    "t=test"

/* Enable send the Information to 1NCE's client support */
#define TROUBLESHOOTING

2. run the demo : the demo will send the information to coap endpoint as a firt step if No ACK come then an SMS to 1nce portal with required informations.

**** Primary case ****

Figure 6. Troubleshooting from the coap endpoint

**** Fallback ****

Figure 7. Troubleshooting from Portal

for more information on the troubleshooting

Table 1. Key Feature of Troubleshooting Message

Table 2. Network Registration Status

When connecting to AWS the setup process is tricky and the policies, rules and certificates need to be setup correctly in order to successfully connect to your thing we automatize all this thing for you to connect fast and performed safety and secure connection and support diffrent type of protocols (UDP/COAP with/without DTLS).