STM32L Smart Card Security System

I’m building a compact security-access module around the STM32L series and need the firmware that makes it all work. The microcontroller must drive an ISO 7816 compliant interface so that a smart card can handle user authentication and access control. Each successful (or failed) attempt then travels out over MQTT to an existing broker for logging and remote policy updates.

Hardware is already laid out, and I’ll share the full schematic, PCB files, and the preferred pinout for the ISO 7816 port. Your task focuses on firmware creation and validation:

• Initialise and manage the ISO 7816 stack on the STM32L, from ATR all the way to processing APDU commands used for authentication.
• Keep power consumption low by leveraging the STM32L’s low-power modes without breaking card timings.
• Package the authentication result, timestamp, and card UID into a lightweight JSON payload and publish it via MQTT (paho-embedded or similar) over my existing network interface.
• Provide a clean CubeIDE project (HAL or LL) with clear inline comments, a README that explains build steps, and a short test routine that demonstrates card insertion, authentication, and MQTT reporting on a NUCLEO or custom board.

Acceptance is straightforward: flash the delivered binary, tap a known test card, and observe the correct MQTT message in my broker’s console within one second. If that passes and the code builds cleanly from source, the milestone is met.

I’m available for quick turn-around answers on hardware quirks or protocol specifics, so feel free to propose your preferred development flow and timeline once you review the brief.