LTE-M & NB-IoT Embedded Firmware Development Services

Phase 01 · Client

Automotive Diagnostic Equipment Client

Adequate Infosoft developed a vehicle diagnostics and predictive-maintenance IoT prototype for an automotive diagnostic equipment client. The client required a compact OBD-II device that could collect vehicle information, operate reliably while a vehicle was parked for long periods and send telemetry securely to a cloud platform.

The product needed to collect diagnostic data from a vehicle's electronic control units (ECUs), while avoiding unnecessary drain on the vehicle battery. Conventional high-bandwidth cellular connectivity was not the best fit because the device's primary requirement was periodic, efficient telemetry rather than constant high-data communication.

Phase 02 · Technology Choice

Why LTE-M Was Selected

The team made the decision to use LTE-M connectivity with a u-blox SARA-R4 LTE-M/NB-IoT modem.

The choice for LTE-M technology was made because the vehicle may stay inactive for a long time. The device will be expected to maintain constant network connection and transfer diagnostic data as per set schedule.

By using Power Saving Mode (PSM) in the firmware the modem was allowed to sleep between transmission periods, which allowed maximizing energy efficiency while keeping a working communication channel to transmit telemetry from the vehicle and its diagnostics.

The design focused on predictable recovery, as vehicle-based devices are prone to ignitional spikes, lack of connectivity, power failures and downtime.

Phase 03 · Engineering

Firmware and Hardware Engineering Approach

An automotive-grade microcontroller manufactured by NXP was employed in this hardware platform with the assistance of an automotive power-management architecture. The firmware was responsible for the acquisition of data from the vehicle through the CAN buses, communication via modems, managing the states of power, batching telemetry, and secure transmission to the cloud.

Key technical work included:

• CAN communication for OBD-II and ECU diagnostic data
• LTE-M modem integration through controlled AT-command handling
• PSM configuration to minimise parked-vehicle battery drain
• Buffered telemetry to avoid loss during a cellular outage
• Secure payload signing using an NXP EdgeLock SE050 secure element
• I2C integration for protected key storage and cryptographic operations
• Network recovery logic for registration failure or modem unresponsiveness
• Cloud-ready telemetry with device identity and timestamped diagnostic records

Each data bundle was cryptographically signed before transmission, enabling server-side verification of its origin and integrity. This was especially important because diagnostic records may be used for maintenance decisions, fleet analysis or evidence-based service workflows.

Phase 04 · Result

Result

The prototype created provided the client with an interconnected platform for running diagnostics that allows for low-power monitoring of vehicles that are parked rather than requiring constant connectivity.

LTE-M and PSM reduced how much power was required by cellular connections while secure element and signed telemetry improved trustworthiness of the data received from the cloud.

The project demonstrates a core principle of LTE-M and NB-IoT firmware development: modem configuration, security, power strategy and recovery logic must be engineered together.

A connected product is only useful when it can continue working safely and predictably beyond the controlled conditions of a development lab.

Related case study: vehicle-diagnostics-iot-prototype-development-nxp-s32k

Service 01

Cellular Modem Integration and AT Command Firmware

Typically, wireless modules are connected through UART, USB or any serial interface using AT commands.

However, it is not merely sending and receiving commands in a commercially used device, as the system also needs to handle problems like delays between requests and responses, unexpected messages from the modem, SIM status, approval from the network, registration failure, PDP context errors, DNS problems and resets.

We develop modular modem-control firmware that manages:

• SIM, eSIM or iSIM initialisation
• Network registration and operator selection
• LTE-M and NB-IoT radio configuration
• APN configuration and IP connectivity
• Signal-quality monitoring and connection recovery
• MQTT, HTTPS, TCP or UDP data sessions
• GNSS requests where supported by the modem
• SMS or fallback alert workflows where required
• Remote configuration and modem firmware support

Our firmware architecture separates critical product functions from modem communication wherever possible. This prevents a slow network operation or modem hang from blocking safety, sensing or control functions.

Service 02

Low-Power Firmware and Battery-Life Optimisation

The battery is crucial for cellular IoT devices. Adequate Infosoft improves the firmware utilizing power-saving features of LTE-M and NB-IoT solutions that have the PSM (Power Saving Mode) and eDRX (extended Discontinuous Reception).

Our experts program the devices to wake up from time to time, gather information from sensors, send some data, and return to sleep mode again. We optimize power consumption while activating the modem, connecting to the network, and positioning the device via GPS.

We analyze the current consumption during different modes of operation, such as idle, sleep, sensor sampling, retry transmissions, and weak signal conditions.

This analysis helps us estimate the necessary battery size, reporting periods, solar support, and maintenance schedule.

Service 03

Telemetry, Cloud Connectivity and Local Data Buffering

A mobile device must not delete valuable information just because it cannot make any connections. We create store-and-forward algorithms which save telemetry in non-volatile memory and send it later when connection is restored. The firmware manages the size of the queue, timestamps data, prevents duplication, decides when to make attempts, and prioritizes the data.

We connect devices with Amazon AWS IoT Core, Azure IoT Hub, any MQTT broker, or any REST-based cloud. Among the regular operations there are provisioning devices, uploading telemetry, issuing commands and events, remote setting, and diagnostics.

To make data manageable at scale, we use structured payloads, versioned messages and clear device identifiers. This supports accurate cloud processing and makes future firmware or backend changes easier to deploy.

Service 04

Secure Firmware, Device Identity and OTA Updates

Every device that connects to the internet requires a plan for security. We take practical precautions that comply with the risk level of the product such as encrypted communication using TLS, the unique identification of devices, management of certificates and keys, secure storage of credentials, use of signed commands, and utilizing secure boot technology if the hardware allows.

For devices deployed in the field, we can implement secure over-the-air (OTA) firmware updates. A strong OTA process includes signed firmware images, integrity checks, controlled download, safe installation, status reporting and rollback support.

These features reduce the risk of bricking devices during an interrupted download or power loss.