Latest / Hardware Startups with Fexingo: Devices, Robotics, and Manufacturing Tech Companies / How Hardware Startups Use FreeRTOS to Avoid Buying an OS
Transcript
- Lucas: So you're a hardware startup. You've got a prototype that works on a development board. You've got a couple of early design wins. And then your CTO says, 'We need to pick an operating system.' Luna: And suddenly you're looking at licensing fees that can run six figures before you've shipped a single unit. Lucas: Exactly. And that's the trap. Because most early-stage hardware teams don't need a full commercial real-time operating system. What they need is a scheduler, some inter-task communication, and maybe a memory allocator. And there's a free option that's been around for nearly two decades: FreeRTOS. Luna: FreeRTOS — the open-source kernel that runs on everything from ARM Cortex-M to risc v. It's in billions of devices. But is it actually production-ready for a startup that's trying to ship? Lucas: That's the right question. Let me give you a concrete case. I talked to the founder of a smart-lock company — let's call them Lockmate, not their real name. They were about to sign a term license with a commercial RTOS vendor. The quote was $12,000 per developer per year, and they had five firmware engineers. With a three-year minimum. That's $180,000 in licensing before they'd sold a single lock. Luna: Plus whatever the runtime royalty is per unit. Lucas: Right. The vendor wanted 50 cents per device. They were projecting 120,000 units in year one. So that's another $60,000. Total: $240,000 over three years, just for the OS. Luna: And they were pre-revenue. Lucas: Pre-seed, actually. But they had a working prototype on a Nucleo board running FreeRTOS that their intern had ported in a weekend. So I asked the founder: 'Why not ship with that?' And he said, 'We thought we needed the commercial version for reliability.' Luna: Which is exactly what the vendor wants you to think. Lucas: Look, FreeRTOS has been deployed in pacemakers, satellite constellations, and automotive ECUs. It's not a toy. But there are real tradeoffs. What you get for free is a minimal kernel: task scheduling, queues, semaphores, timers, and memory management. What you don't get is device drivers, a file system, a TCP/IP stack, or any security layer. Luna: So you're building those yourself, or pulling in other open-source libraries. And that takes engineering time, which is also expensive. Lucas: Right. The Lockmate team spent about four engineering-months integrating FreeRTOS with their Wi-Fi module's SDK and writing a simple flash file system. At a blended rate of $15,000 a month, that's $60,000 in engineering cost. Still way less than $240,000. And they owned the code. Luna: But here's where I push back. Four months of firmware work on a pre-revenue startup is a big chunk of your runway. And if you make a mistake in the scheduler configuration, you could have a device that locks up in the field. The commercial RTOS vendor gives you a support line. Lucas: Absolutely. And that's the decision point. There's a clear inflection where it makes sense to switch. A 2025 survey from Embedded.com found that 68 percent of hardware startups that started with FreeRTOS migrated to a commercial RTOS by the time they raised their Series A. The trigger was almost always the same: they needed deterministic behaviour for a safety-critical feature, or they needed a certified security stack for enterprise sales. Luna: So the advice isn't 'never use commercial.' It's 'don't pay for it before you have to.' Lucas: Exactly. Ship with FreeRTOS. Prove product-market fit. Get your first thousand units in the field. Then, when your largest customer demands a signed SLA and a guaranteed response time, you have revenue to fund the license. Luna: And you can negotiate from a position of strength because you're already running. Lucas: If these conversations are useful for what you're building or running, you can help keep them going — a couple of dollars a month is genuinely what keeps these ad-free. It's buy me a coffee dot com slash fexingo. No pressure, just if you've gotten something out of the show. Luna: Yeah, it makes a real difference. And we don't run ads, so listener support is what keeps the lights on. Lucas: Back to the RTOS decision — there's another hidden cost that startups don't think about: debugging. With a commercial RTOS, you get a vendor-provided debugger plugin that shows you task states, stack usage, and priority inversions in real time. Luna: With FreeRTOS, you're using printf and a logic analyser. Lucas: Or a free tool like Tracealyzer, which has a community edition. But the point is, debugging a preemptive priority-based scheduler without vendor tools is harder. The Lockmate team told me they spent two weeks tracking down a priority inversion bug that a commercial tool would have shown them in an hour. Luna: But two weeks of engineering time is still cheaper than $240,000. Lucas: At this stage, yes. And there's a pattern here. The startups that get into trouble are the ones that sign a multi-year license before they've actually validated that they need the commercial features. I have a rule: never sign a term license until you've proven you need a full posix compliant OS. Luna: Define 'full posix compliant'. Because a lot of founders hear that and think they need it for portability. Lucas: Right. POSIX is a standard for Unix-like system interfaces. A full posix compliant RTOS gives you things like pthreads, file descriptors, and sockets. If you're writing your application code to POSIX APIs, you can theoretically move it to another OS later. But FreeRTOS doesn't have a POSIX layer. So your code is tightly coupled to the FreeRTOS API. Luna: Which means if you do migrate later, you're rewriting a lot of the application logic. Lucas: Exactly. And that's a legitimate reason to start with a commercial OS if you know you're going to need it. But most hardware startups don't know that at the prototype stage. They're still figuring out what the product even does. Luna: So what's the playbook? Step one: prototype on FreeRTOS. Step two: ship first production run on FreeRTOS. Step three: if you hit the wall — latency, security certs, or customer demands — then evaluate commercial options. Lucas: That's exactly it. And when you evaluate, you have leverage. You can say, 'We're running on FreeRTOS. We have 10,000 units in the field. We need to move to your OS. What's the best you can do?' And suddenly that $12,000 per developer becomes $4,000. Luna: Because they want your volume. And they know you can stay on FreeRTOS if you have to. Lucas: One more thing: the commercial RTOS vendors have caught on to this. Several now offer free or low-cost entry tiers for startups with under $1 million in funding. Wind River has a startup program. Green Hills has a reduced-rate license for companies under 10 employees. So it's worth checking. Luna: But the default should still be FreeRTOS. Because the biggest risk at the prototype stage isn't a priority inversion bug — it's running out of money. Lucas: And a $240,000 licensing bill before you've sold a single unit is a great way to run out of money. So, rule of thumb: if you're pre-Series A and pre-revenue, ship on FreeRTOS. You can always upgrade later. Luna: And for founders who are already on a commercial RTOS and wondering if they overpaid — what's the move? Lucas: Check your contract. Some vendors allow you to downgrade to a free tier if you haven't used certain features. And if you're locked in, your next product line can start on FreeRTOS. That's what a medical device startup I spoke to did — they kept their legacy product on the commercial OS and designed the new one on FreeRTOS. Saved them $90,000 a year. Luna: So the takeaway: don't buy an OS until the OS is the bottleneck. Lucas: That's the headline. And if you're listening and you've made the switch, or you're debating it, I'd love to hear how it went. We might do a follow-up episode with listener case studies. Luna: That would be great. For now, the lesson is clear: your first OS should be the one that costs you zero dollars and gets you to market fastest. Lucas: And that, nine times out of ten, is FreeRTOS.