The Agile Embedded Podcast

We talk with Tobias Kästner, a physicist-turned-software-architect and technical consultant at Inovex, about his journey from painfully slow hardware-software integration cycles to achieving three-week hardware sprints. Tobias shares hard-won lessons from medical device development, where fuzzy requirements and constant feedback from life scientists forced his team to rethink traditional approaches.

The conversation centers on practical techniques: breaking monolithic PCB designs into modular "feature boards" connected via shields (think Arduino-style), using Git for hardware version control with SHA-1s printed on silkscreens, and leveraging tools like Zephyr RTOS to enable plug-and-play firmware that matches the modularity of the hardware. Tobias explains how relaxing constraints like board size and using automation to merge schematics allowed his team to iterate rapidly while maintaining a clear path to final form-factor designs. We discuss how this approach scaled to projects with 120+ people across multiple teams, and why the interplay between system architecture, organizational structure, and information flow matters more than most realize.

Key Topics

[02:30] The painful reality of traditional hardware development: six-month wait for hardware, nine months of debugging

[08:00] Breaking apart monolithic PCB designs into modular feature boards with shield connectors

[12:45] Relaxing constraints: larger board areas, autorouting, and prioritizing testability over final form factor

[18:20] Version control for hardware: putting schematics in Git and printing SHA-1s on silkscreens

[22:00] Using automation to merge feature board schematics into final form-factor designs

[26:15] Firmware architecture: NuttX, Zephyr, KConfig, and device trees for modular, plug-and-play software

[35:40] Scaling agile hardware-software co-development to 120+ person projects across multiple teams

[39:00] The interplay of system architecture, organizational architecture, and information architecture

Notable Quotes

"When the board arrived, not a single line of code had been written for it because no one had been able to touch it. It took us nine additional months to debug all the things out of it." — Tobias Kästner

"I've never seen any board working the first time. I've never seen any prototype without thin wires patching things out, but that's maybe a different story." — Tobias Kästner

"We cannot think these architectures as independent of one another. If we have limitations in two of these architectures, we will see these limitations in the third architecture as well." — Tobias Kästner

Resources Mentioned

Inovex - Tobias's company offering engineering consulting services, trainings, and expertise in embedded systems, IoT, and full-stack development

Zephyr RTOS - Open-source real-time operating system with KConfig, device tree support, and extensive driver library that Tobias recommends for modular firmware development

NuttX RTOS - Apache Foundation RTOS with clean device driver model and KConfig support that Tobias used in earlier projects

KiCad - Open-source PCB design software with emerging Python API support for schematic automation

Services and Contact

Through Inovex, Tobias provides trainings for both Zephyr and Yocto Linux, as well as consultancy and engineering support for embedded projects -- from 1-2 day workshops evaluating architectural state and cost/benefit analysis, to first prototypes, to full-fledged software development. With partners such as alpha-board (Berlin) and Blunk electronic (Erfurt), they also offer agile hardware services and help teams get started with the methods discussed in this episode.

Email: [email protected]

Tobias Kästner on LinkedIn

tobiaskaestner on the Zephyr Discord Channel

Links

Companies:

Inovex -- Embedded Systems

Blunk electronic

alpha-board

Navimatix

Talks and publications:

Modular and Agile HW Development (2018 talk)

Leveraging Zephyr's HW Abstraction for Agile Systems Engineering (2023 talk)

Whitepaper: Agile in der Hardware -- by Gregor Gross, Christoph Schmiedinger, and Tobias Kästner

Leveraging Zephyr for Functional Architecture Decomposition (2025 talk)

Books recommended by Tobias:

Small Groups as Complex Systems -- Holly Arrow et al., SAGE Publications

The Dao of Complexity -- Jean Boulton, DeGruyter

You can find Jeff at https://jeffgable.com.
You can find Luca at https://luca.engineer.
Want to join the agile Embedded Slack? Click here
Are you looking for embedded-focused trainings? Head to https://agileembedded.academy/
Ryan Torvik and Luca have started the Embedded AI podcast, check it out at https://embeddedaipodcast.com/

We explore how test-driven development (TDD) remains essential—perhaps more than ever—when working with AI coding tools. Luca shares his evolved workflow using Claude Code, breaking down how he structures tests in three phases: test ideas, test outlines, and test implementations. We discuss why TDD provides the necessary control and confidence when AI generates code, how it prevents technical debt accumulation, and why tests serve as precise specifications for AI rather than afterthoughts.

The conversation covers practical challenges like AI's tendency toward "success theater" (overly generous assertions), the importance of maintaining tight control over code quality, and why the bottleneck in AI-assisted development isn't code generation—it's expressing clear intent. We also touch on code spikes, large-scale refactorings, and why treating AI development as pair programming keeps you in the driver's seat. If you're wondering whether TDD still matters when AI writes your code, this episode makes a compelling case that it matters more than ever.

Key Topics

[02:30] Why TDD still matters with AI: confidence and control over generated code

[06:45] Tests as specifications: describing desired behavior to AI rather than writing prompts

[09:20] The three-phase test workflow: test ideas, test outlines, and implementations

[15:30] Pair programming with AI: staying at the conceptual level while AI handles implementation

[20:15] Code spikes and exploration: using AI to answer questions before writing production tests

[24:40] AI failure modes: over-mocking and "success theater" with weak assertions

[28:50] Large-scale refactorings: how AI excels at updating hundreds of tests simultaneously

[32:10] The real bottleneck: expressing intent and specifications, not code generation speed

Notable Quotes

"As far as I am concerned, test-driven development is just about writing prompts for the AI that it can then use to build what you want it to build." — Luca

"If you expect that a five-line prompt resulting in 10,000 lines of code will not result in 9,995 lines of uncertainty, you're just deluding yourself." — Luca

"You can be five times faster than you were before and still maintain a very high production level quality code, but you probably can't be a hundred times faster." — Jeff

Resources Mentioned

Claude Code - Terminal-based AI coding assistant that Luca uses for TDD workflows, keeping conceptual work separate from code-level work

Embedded AI Podcast - Luca's separate podcast focusing on AI in embedded systems, co-hosted with Ryan Torvik

Luca's AI Training Courses - Hands-on trainings for using AI in embedded systems development (and much more!)

links to all of Luca's work - Training, consulting, podcasts, conference talks and everything else

You can find Jeff at https://jeffgable.com.
You can find Luca at https://luca.engineer.
Want to join the agile Embedded Slack? Click here
Are you looking for embedded-focused trainings? Head to https://agileembedded.academy/
Ryan Torvik and Luca have started the Embedded AI podcast, check it out at https://embeddedaipodcast.com/

In this second part of our series on engineering organizations, Jeff and Luca explore how companies that build products should focus their efforts differently depending on their stage and scope. We start with startups and early-stage companies desperately searching for product-market fit, where the brutal truth is: quality doesn't matter yet. Your MVP should embarrass you—if it doesn't, you waited too long. We discuss the critical mental shift from throwaway prototypes to proper engineering once validation arrives, and why technical founders often fail by solving the wrong problem brilliantly.

Moving up the ladder, we examine narrow-focus companies that have found their niche—like the German firm that does nothing but maintain a 100-year-old anchor chain machine, or specialists in medium-power electrical switches. These companies win through efficiency and deep expertise, but face existential risk if the market shifts. Finally, we tackle wide-focus companies introducing multiple product lines, where the challenge becomes running internal startups while managing established products, each requiring radically different approaches. The key insight: your focus must match your product's lifecycle stage, whether that's ruthless speed, cost optimization, or high-level process learning.

Key Topics

[02:30] Startups and early-stage companies: the existential search for product-market fit

[06:45] The MVP philosophy: if you're not embarrassed, you waited too long

[11:20] Quality vs. speed vs. scope: why quality doesn't matter in early stages

[15:40] The Potemkin village approach: building facades to validate demand

[19:15] Embedded products and MVPs: when physical products need creative shortcuts

[23:50] The critical switch: from prototypes to proper engineering after validation

[28:30] Narrow-focus companies: German hidden champions and deep specialization

[34:10] Wide-focus companies: running internal startups within established organizations

[40:25] Product teams and parallel focuses: managing different lifecycle stages simultaneously

[45:00] Large established companies: high-level process learning and avoiding organizational weight

Notable Quotes

"If you read the Lean Startup, they will explicitly say: if you weren't embarrassed by your MVP, you waited too long. It really has to be painfully flimsy because you cannot afford to do it well." — Luca

"Quality doesn't even factor because you're very explicitly building mock-ups from chewing gum and paper mache. They are fully intended to be thrown away." — Luca

"Getting that product-market fit is existential. You will die if you do not get it and get it relatively quickly." — Jeff

Resources Mentioned

The Lean Startup - Eric Ries' book discussing MVP philosophy and the importance of being embarrassed by your first product

The Mom Test - Rob Fitzpatrick's book about getting real customer feedback and validation through financial commitment

The Art of Innovation - Tom Kelley's book on IDEO's design process, including the clothespin switch story

Luca's Website - Trainings on embedded agile, AI in embedded systems, and more

Jeff's Website - Consulting services for medical device software development

You can find Jeff at https://jeffgable.com.
You can find Luca at https://luca.engineer.
Want to join the agile Embedded Slack? Click here
Are you looking for embedded-focused trainings? Head to https://agileembedded.academy/
Ryan Torvik and Luca have started the Embedded AI podcast, check it out at https://embeddedaipodcast.com/

In this first part of a two-part series, Jeff and Luca explore how different types of service-oriented engineering organizations should focus their learning and improvement efforts. Drawing from their consulting experience, they examine three distinct categories: product development firms that turn client ideas into reality, engineering development firms that sell specialized technical expertise, and solo engineers who package all necessary knowledge into one person.
The core insight: what you should focus on learning depends entirely on what you're actually selling. Product development firms need to master the entire client journey and product design process, not just engineering excellence. Engineering development firms must become technical wizards in a specific domain that clients actually value. Solo engineers face the challenge of needing deep expertise while wearing every business hat. Across all three types, the common traps are the same: focusing too much on craft and too little on client experience, failing to specialize, and not investing enough in teaching as marketing.
Throughout the discussion, Jeff and Luca emphasize that for service firms, you are the product - and that changes everything about where you should direct your improvement efforts. The conversation is grounded in real experiences, including some cautionary tales about firms that tried to be everything to everyone.
Key Topics
[00:00] Introduction: Two-part series on engineering organizations and their different focuses
[02:30] Overview of the framework: Service firms vs. product-building companies
[05:15] Product development firms: Why engineering excellence isn't enough
[08:45] The critical importance of product design and client guidance over pure engineering
[12:20] Process-level learning: Shortening cycle times and enabling rapid prototyping
[15:40] The Irinos example: In-house board manufacturing to tighten feedback loops
[18:30] Requirements will always change - designing for learning, not perfection
[21:00] The danger of being a generalist: Why specialization matters for service firms
[24:15] Engineering development firms: Selling technical expertise, not complete products
[27:45] Technology-focused learning: Going deep on specific technical capabilities
[30:20] The trap of becoming a commodity: Why domain expertise beats technology alone
[33:40] The forklift invoice review example: You can't specialize too narrowly
[35:30] Solo engineers: The complete package vs. temporary employee trap
[39:00] Common failures across all service firms: Too much craft focus, too little client experience and marketing
[41:30] Teaching as the best form of marketing for technical service firms
Notable Quotes
"The customers don't actually hire them for their engineering skills. They are sort of a given. But what such a product development firm should offer the client is guiding them through the development process, which they don't have enough skills for to do it on their own." — Luca
"Engineering is not the point. The unit of work is delivering a working product to the client that satisfies their business case, that has a reasonable cost to manufacture, and that you feel confident your own client has validated their market." — Jeff
"It's not that engineering is irrelevant, but rather that it's table stakes. This is just taken for granted, but what such a product development firm should offer is guiding them through the development process." — Luca
"You almost can't be narrow enough. I remember our friend Philip Morgan having this example of a company that specializes in reviewing invoices of forklift repairs. This is what they do. They review forklift repair invoices. And they're doing very well apparently." — Luca
"Teaching and giving information and solving problems publicly is the best form of marketing. It's not advertising. It's building trust with an audience." — Jeff
Resources Mentioned
IDEO - Prototypical design firm mentioned as an example of companies specializing in product design
IRNAS - Product development firm with in-house board manufacturing capabilities, featured in previous episodes, exemplifying tight feedback loops
Philip Morgan - Consultant and friend mentioned for his example about specialization (forklift invoice review company)
Jeff Gable's website - Jeff's consulting services for medical device software development and advisory
Luca Ingianni's website - Luca's training products and resources for embedded systems, IoT, and AI
Connect With Us
Stay tuned for Part 2, where we'll explore organizations that build products and what they should focus on when the market decides
If you're in the medical device industry and need help with embedded software - either writing it or navigating the regulatory landscape - reach out to Jeff at jeffgable.com
Check out Luca's training products for embedded systems, IoT, and AI at luca.engineer
Reflect on your own organization: Are you focusing on the right things for the type of service firm you are? Are you specializing enough?

You can find Jeff at https://jeffgable.com.
You can find Luca at https://luca.engineer.
Want to join the agile Embedded Slack? Click here
Are you looking for embedded-focused trainings? Head to https://agileembedded.academy/
Ryan Torvik and Luca have started the Embedded AI podcast, check it out at https://embeddedaipodcast.com/

In this episode, we sit down with Milica Kostic, an embedded software architect from Belgrade, Serbia, to discuss her journey from C/C++ to Rust and what it means for embedded development. Milica shares her experience adopting Rust in production environments, starting with an embedded Linux project using a microservice architecture that allowed for clean isolation of Rust code.
We explore the practical realities of learning Rust as an experienced C/C++ developer - yes, there's a learning curve, and yes, the compiler will slap you on the wrist frequently. But Milica explains how the development experience, with cargo as a package manager and built-in tooling for testing and static analysis, makes the journey worthwhile. She's candid about where Rust shines (embedded Linux, greenfield projects) and where challenges remain (microcontroller support, IDE tooling, vendor backing).
The conversation touches on the bigger question facing our industry: with memory safety becoming critical in our connected world, what role should Rust play in new embedded projects? While Milica takes a measured stance - acknowledging that C and C++ aren't going anywhere - she's clearly excited about Rust's potential, especially in safety-critical domains like medical devices. Whether you're Rust-curious or still skeptical, this episode offers a grounded perspective from someone who's actually shipped production code in Rust.
Key Topics
[02:30] Milica's background in embedded systems and her journey from electrical engineering to embedded software development, with focus on safety-critical industries like medical devices
[04:15] The path to adopting Rust: from first hearing about it in 2020 to finding a client project willing to embrace it, and the importance of having experienced Rust developers on the team
[07:00] Choosing the right project for Rust adoption: embedded Linux with microservice architecture as an ideal starting point, avoiding complex C/C++ interoperability
[10:45] The learning curve: getting used to the Rust compiler's strictness, discovering the ecosystem of unofficial but widely-used crates, and how learning Rust improved C++ skills
[14:20] What makes Rust development pleasant: cargo as package manager, built-in testing and static analysis, cleaner code organization with modules, and writing unit tests alongside source code
[17:30] Current limitations: lack of official vendor support for microcontrollers, community-driven development, potential gaps in certified stacks (like BLE), and IDE support challenges
[20:15] Interfacing Rust with C and C++: C binding works well, C++ has limitations with inheritance and templates, and the safety considerations when using unsafe code blocks
[25:40] Integrating Rust into legacy projects: when it makes sense (isolated new features requiring memory safety) and when it doesn't (just for experimentation), plus maintenance considerations
[30:00] The big question: Is it irresponsible not to use Rust for new projects? Discussion of Philip Marcraff's strong stance and Milica's more nuanced view considering team knowledge, existing tooling, and project context
[33:45] The influence between languages: how C++ is learning from Rust's memory safety features, and why the borrow checker is harder to retrofit than basic safety improvements
[36:20] Rust in operating systems: adoption in the Linux kernel and Microsoft Windows, and major tech companies pushing C++/Rust interoperability forward
[39:00] The future of Rust in embedded: Milica's view that C, C++, and Rust will coexist, each with their own use cases, advantages, and trade-offs
Notable Quotes
"Learning Rust has also made me a better C++ developer as well. Once you get used to those rules, you apply them in C++ as well." — Milica
"Just like writing Rust code is pleasant. It flows much nicer than or easier than it would with C++, for example. The way you organize your code, in my opinion, is also cleaner." — Milica
"If you are developing Rust for embedded systems on microcontrollers, you need to be aware that there is no official vendor support. Everything currently is open source and driven by the community." — Milica
"You definitely do not lose benefits of using Rust for the rest of your codebase when using a C library. That C library is isolated, and if there are some memory issues, then you know where to look." — Milica
"I think most of the benefits come from starting with Rust in the first place. So having a clean slate, starting a new product, new project with Rust. That's where you see the most benefits." — Milica
Resources Mentioned
Embassy - An async framework used in embedded Rust projects, mentioned as a good starting point for greenfield embedded development
Zephyr RTOS - Real-time operating system that is working on official Rust integration, though not fully there yet
Rust Rover - JetBrains' official IDE for Rust development, released about a year and a half ago, though with some limitations for embedded development
Zed - A new IDE written completely in Rust, mentioned as an emerging option for Rust development
Slint - A Rust-based GUI framework for embedded systems
Embedded Online Conference - Conference where Milica gave a talk on Rust for embedded systems - link to her presentation in show notes
Milica's LinkedIn
Milica's talk on Rust at the Embedded Online Conference

You can find Jeff at https://jeffgable.com.
You can find Luca at https://luca.engineer.
Want to join the agile Embedded Slack? Click here
Are you looking for embedded-focused trainings? Head to https://agileembedded.academy/
Ryan Torvik and Luca have started the Embedded AI podcast, check it out at https://embeddedaipodcast.com/