Code that performs
when it has to.
Firmware development and consulting for connected devices — built with the rigor of mission-critical environments, delivered with the agility your product needs.
// about
CriticalBits is the independent practice of Javier Navarro, a senior firmware engineer specialized in embedded systems and BLE connectivity for connected devices.
My background is in mission-critical development environments — where failures in design or testing carry real consequences. That experience shaped a permanent approach: structured planning from day one, rigorous testing practices, and architecture decisions made for the long term, not just the prototype.
I work with teams building connected and embedded products across industrial automation, smart infrastructure, and consumer electronics. I'm equally comfortable joining a project from day one or stepping in to solve a specific technical challenge on an ongoing one.
Deliverables-based engagements. Clear milestones. No surprises at the end of the sprint.
Modular, documented, production-oriented firmware — designed to be maintained by someone other than the original author.
Fewer projects, deeper engagement. One client's firmware deserves full attention, not divided focus.
// services
BLE with Nordic nRF52/nRF53/nRF54 series. STM32 and ARM Cortex-M systems. Peripheral integration, low-level hardware bring-up, and low-power design.
Modular firmware architecture for scalable products. Communication protocol design. Firmware structure for long-term product evolution. Risk-aware technical planning.
Cybersecurity practices for connected embedded devices. Secure communication and data integrity in IoT systems. Threat-aware firmware design from the ground up.
Firmware code review and architecture assessment. Technical guidance for early-stage hardware products. Documentation and structured development practices.
Assessment of existing firmware or guidance on architectural decisions. Covers modularity, hardware abstraction, scalability, and long-term maintainability.
Adapting agile methodologies to firmware and hardware constraints. Sprint structure, definition of done, testing strategies, and documentation that scales.
// development cases
Design firmware for a connected device requiring simultaneous acquisition of inertial data and impedance measurements, with real-time BLE transmission — under strict low-power constraints and regulatory requirements. A paired wireless charging device was developed as part of the same product ecosystem.
Extend the operational range of a BLE-based product beyond point-to-point connectivity limits, enabling reliable communication across larger physical spaces without compromising power efficiency or connection stability.
Develop firmware for an early-stage sensing device using next-generation Nordic silicon, adopting Zephyr RTOS as the foundation — setting up a modern, scalable stack from scratch with production quality in mind from day one.
Eliminate manual testing bottlenecks in BLE device validation — providing a repeatable, scriptable infrastructure covering connection behavior, GATT service validation, and data integrity across firmware versions.
// why uruguay
Uruguay has built one of the most credible tech ecosystems in Latin America — not by accident, but through decades of investment in education, infrastructure, and export-oriented development culture.
For US companies, working with Uruguayan engineers means nearshore quality: timezone alignment, cultural compatibility, English proficiency, and a track record of delivering to international standards.
Timezone alignment — UTC-3 overlaps with the full North American workday, from EST to PST.
English proficiency — among the highest in Latin America; Montevideo scores at European levels.
US-aligned work culture — 85% of Uruguayan IT exports go to the United States. The workflows, tools, and expectations are already familiar.
Cybersecurity leadership — Uruguay ranks top-3 in ITU America's Global Cybersecurity Index.
Political and legal stability — strong IP protection, rule of law, and one of the most stable business environments in the region.
// tech stack
// how i work
Structured around milestones and clear outputs — not billable hours. You always know what you're getting and when.
Communication via email or messaging platforms (Slack, Teams). Regular progress updates at each milestone, so you have visibility without constant check-ins.
Based in Uruguay (UTC-3), available from 7 PM local time — aligning with afternoon to early evening across all North American time zones.
A limited number of projects at a time. Not a dev shop — a senior engineer who gives your firmware the attention it deserves.
// contact
Whether you're starting from scratch or need a specific problem solved — reach out and let's figure out if we're a good fit.
[email protected]