Lead Firmware Engineer

Company Description Digital Trust Infrastructure India Limited is a deep-technology company building foundational infrastructure for India’s digital economy. The organization focuses on structural gaps between how systems are designed and how they operate in practice, addressing issues often unnoticed until they become critical. Rather than following short-term trends, the company develops robust platforms that strengthen trust and reliability across digital systems. Headquartered in India and building for India first, its work is designed to have impact both domestically and globally.

Location: Pune, India

Experience: 7+ Years

Employment Type: Full-Time

About the Role

We are seeking an exceptionally skilled Lead Firmware Engineer to pioneer the hardware-software boundary for a highly secure, next-generation financial technology platform. In this role, you will design, develop, and maintain the firmware for a custom USB-to-BLE Smart Card Bridge .

Key Responsibilities

• Architecture & Firmware Design: Lead the design and implementation of production-grade embedded C/C++ firmware.
• USB Host Stack Implementation: Configure and optimize USB Host peripheral to enumerate, establish power delivery, and communicate with physical USB tokens using the CCID (Chip Card Interface Device) protocol.
• BLE GATT Server Development: Architect a secure, highly efficient BLE 5.0 GATT server with custom services and characteristics to handle low-latency transmission of cryptographic payloads (APDU streams).
• Protocol & APDU Parsing: Implement the formatting, parsing, and sequencing of ISO-7816 APDU (Application Protocol Data Unit) commands sent between the client application and the smart card chip.
• Power & Hardware Optimization: Collaborate on hardware schematic reviews to manage power states, handle 5V boost converters for the USB VBUS line, monitor LiPo battery levels, and implement deep-sleep/wake-up triggers to maximize battery life.
• Security & Memory Hardening: Enforce strict cryptographic boundaries within the firmware, including the secure handling of ephemeral session tokens, prevention of buffer overflows, and explicit memory zeroing of sensitive buffers post-execution.

Required Technical Skills

• Embedded C/C++ & ESP-IDF (7+ Years): Expert-level proficiency in writing robust, low-level embedded systems code.
• USB Host Stack Experience: In-depth, practical knowledge of the USB 2.0 protocol, USB Host configuration, descriptors, enumeration, and explicitly the CCID class or mass storage/CDC interaction at a packet level.
• BLE Architecture: Extensive experience configuring BLE stacks, connection parameters, passkey/numeric comparison pairing, notification/indication optimization, and managing concurrent BLE connections.
• Smart Cards & Cryptography: Hands-on familiarity with ISO-7816 standards, APDU command-response structures, and symmetric/asymmetric cryptographic concepts (SHA-256, RSA/ECC signatures).
• FreeRTOS: Strong understanding of real-time operating systems concepts, task scheduling, mutexes, semaphores, and inter-task messaging queues.
• Hardware Debugging: Expert usage of digital oscilloscopes, logic analyzers (e.g., Saleae), Wireshark (for BLE packet captures), and JTAG debuggers to trace and diagnose timing-critical firmware issues.