COREDUMP #003: Pebble's Code is Free: Three Former Pebble Engineers Discuss Why It's Important

03/26/25 • 48 min

In this episode of Coredump: Embedded Insights, the Memfault founders—François Baldassari and Chris Coleman—are joined by Brad Murray, former Pebble firmware lead, to explore the now open-sourced Pebble OS. They share war stories from the early days of embedded development, unpack why Pebble’s firmware architecture was years ahead of its time, and highlight the lessons embedded engineers can take from a real, production-grade consumer device.

Topics include:

Why open-sourcing Pebble OS is a big deal
The platform strategy behind a single codebase for multiple hardware SKUs
Custom file systems, app sandboxing, and crash recovery in the real world
The debugging hacks, performance tricks, and developer tools they wish they had built sooner

This is a rare peek behind the scenes of one of the most iconic embedded products ever shipped.

Topics include:

Why open-sourcing Pebble OS is a big deal
The platform strategy behind a single codebase for multiple hardware SKUs
Custom file systems, app sandboxing, and crash recovery in the real world
The debugging hacks, performance tricks, and developer tools they wish they had built sooner

This is a rare peek behind the scenes of one of the most iconic embedded products ever shipped.

Previous Episode

#005: The Current Realities of Cellular IoT

In today’s Coredump Session, we zoom in on the rapidly evolving world of cellular IoT—what’s working, what’s changing, and what developers should know. With expert insight from Fabien Korheim of ONES, the conversation breaks down MVNOs vs MNOs, dives into certification hurdles, explores connectivity trade-offs like NB-IoT vs LTE-M, and unpacks why cellular is quietly powering more devices than you think. Whether you're building metering devices or baby monitors, this one hits the full stack—from tech to business models.

Key Takeaways:

MVNOs simplify global IoT deployments by abstracting regional carrier relationships and reducing SKU complexity.
LTE-M is currently the safest bet for low-power cellular applications, with 5G RedCap positioned as a future alternative.
Certification processes are lighter with MVNOs, especially when using pre-approved modules.
Cellular IoT is ideal where Wi-Fi isn’t guaranteed, like basements, forests, and mobile tracking.
Consumer IoT has huge untapped potential—cellular can dramatically improve usability and reduce returns.
Battery life and data costs are major design considerations, especially when scaling fleets globally.
Multiradio devices and smart fallback strategies (e.g. BLE/Wi-Fi + Cellular) are becoming more common.
Debugging tools and observability platforms are essential for maintaining reliability across networks, devices, and regions.

Chapters:

00:00 Episode Teasers & Intro02:34 MVNO vs MNO: What’s the Difference?06:28 Certifications, SIMs & Simplifying Deployment12:31 NB-IoT, LTE-M, LoRaWAN & Satellite—Explained23:43 5G for IoT: Hype or Here?27:14 Top Use Cases: Meters, Trackers & Wildlife33:28 The Big Opportunity: Cellular in Consumer Devices36:33 Business Models: Who Pays for Cellular?37:49 Getting Started: Kits, SIMs & Copy-Paste Firmware41:59 Common Mistakes & What to Watch in the Field47:15 What to Measure: Observability That Scales49:13 Q&A: Prioritization, Firmware Updates, RedCap & More

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Next Episode

#006: Pebble’s Code is Free: Three Former Pebble Engineers Discuss Why It's Important (PART 2/2)

In today’s Coredump Session, the team reunites to unpack the behind-the-scenes lessons from their time building firmware at Pebble. This episode dives into the risks, decisions, and sheer grit behind a near-disastrous OTA update—and the ingenious hack that saved a million smartwatches. It’s a candid look at the intersection of rapid development, firmware stability, and real-world consequences.

Key Takeaways:

Pebble’s open approach to developer access often came at the cost of security best practices, reflecting early startup trade-offs.
A critical OTA update bug almost bricked Pebble devices—but the team recovered using a clever BLE-based stack hack.
Lack of formal security measures at the time (e.g., unsigned firmware) unintentionally enabled recovery from a serious update failure.
Static analysis and test automation became top priorities following the OTA scare to prevent repeat incidents.
The story reveals how firmware constraints (like code size and inline functions) can lead to high-stakes bugs.
Investing in robust release processes—including version-to-version OTA testing—proved vital.
Real security risks included impersonation on e-commerce platforms and potential ransom via malicious OTA compromise.
The importance of "hiring your hackers" was humorously noted as a de facto security strategy.

Chapters:

00:00 Episode Teasers & Welcome

01:22 Why Pebble’s Firmware Was Open (and Unsigned)

05:01 The Security Tradeoffs That Enabled Speed

11:00 The OTA Bug That Could Have Bricked Everything

15:26 Hacking Our Way Out with BLE Stack Overflow

17:47 Lessons Learned: Test Automation & Static Analysis

26:30 How Pebble Built a Developer Ecosystem

29:56 CloudPebble, Watchface Generator & Developer Tools

42:55 Backporting Pebble 3.0 to Legacy Hardware

49:02 The Bootloader Rewrite & Other Wild Optimizations

53:31 Simulators, Robot Arms & Debugging in CI56:40 Firmware Signing, Anti-Rollback & Secure Update