Short answer: Firmware for an integrated device is developed in a co-design loop with the printed circuit board: the architecture (MCU or SoC, memory, peripherals, power modes, interfaces) is fixed together with the schematic; board bring-up delivers drivers, a hardware abstraction layer and a bootloader on the first prototype; the application layer adds the RTOS, control logic, connectivity protocols and over-the-air updates; automated hardware-in-the-loop tests and a factory test program are written before series production; and production programming, provisioning and field updates are designed in from the start. Comtec Labs develops firmware and hardware in one team so that each prototype revision improves both.
The co-design loop, step by step
| Step | Firmware work | Hardware decision it drives |
|---|---|---|
| 1. Requirements and architecture | Processing budget, memory, real-time needs, power modes, security level, interfaces | MCU/SoC choice, memory, power tree, debug and programming header |
| 2. Board bring-up | Clock and power configuration, drivers, HAL, bootloader, first LED and UART | Pull-ups, boot pins, test points, sensor placement, EMC fixes |
| 3. Application and connectivity | RTOS tasks, control loops, CAN/Modbus/Ethernet/BLE/LTE stacks, OTA update, logging | Antenna and RF layout, connector pinout, watchdog and brown-out design |
| 4. Verification and test automation | Unit tests, hardware-in-the-loop rigs, factory test firmware, calibration routines | Test points, boundary-scan chain, fixture interface |
| 5. Production and field | Programming and provisioning at the line, secure key injection, update pipeline, diagnostics | Serial-number storage, secure element, service connector |
What good embedded firmware practice looks like
- Version control, code review and continuous integration builds for every commit, also for firmware.
- A hardware abstraction layer so the application survives an MCU or sensor change.
- Secure boot, signed updates and encrypted provisioning where the device is networked; the EU Cyber Resilience Act makes this a market requirement for connected products.
- Defensive coding in C/C++ (MISRA-style rules, static analysis) and watchdog-supervised tasks.
- Factory test firmware that exercises every interface, so the production line finds hardware faults in seconds.
Why one team for hardware and firmware
When the firmware engineer sits next to the layout engineer, the debug header, the test points, the sensor orientation and the power sequencing are right on the first prototype. When a bring-up problem appears, it is fixed in the schematic and the driver on the same day rather than escalated between two companies. That is the practical meaning of R&D-driven manufacturing.
Key facts
- Firmware typically consumes 40–60 % of the engineering hours of an integrated device; the rest is electronics and mechanics.
- A hardware abstraction layer turns an MCU end-of-life from a rewrite into a port.
- Signed OTA updates and secure provisioning are becoming mandatory for connected products sold in the EU (Cyber Resilience Act).
- Comtec Labs programs and provisions devices on the production line and delivers the test firmware with the product.
Typical stacks we work with
ARM Cortex-M microcontrollers (STM32, NXP, Nordic, Espressif) with bare-metal or FreeRTOS/Zephyr, embedded Linux on Cortex-A and NXP i.MX class SoCs, fieldbus and industrial protocols (CAN, Modbus, EtherCAT, OPC UA), wireless (BLE, Wi-Fi, LTE-M/NB-IoT, LoRa) and edge AI inference on microcontrollers and accelerators.
Frequently asked questions
Do you develop firmware for boards you also manufacture?
Yes, that is the normal case: hardware, firmware, test software and production in one project.
Who owns the firmware source code?
The customer, under the development agreement. We deliver the repository, build system and documentation.
Can you add firmware to an existing product?
Yes. We start with a review of the hardware and the existing code, then plan the work in verifiable milestones.
How do you handle updates in the field?
With a bootloader that verifies signed images, an update pipeline you control and a rollback strategy, designed in from the first prototype.
Ready to reduce PCB surprises?
Comtec Labs offers a full suite of services to streamline your workflow:
PCB design service
PCB prototyping service
PCB component sourcing
PCB component assembly
PCB testing service
PCB repair and modifications
Printed circuit board production
PCB mass production