Latest Posts (20 found)
Daniel Mangum 6 days ago

Using a Laptop as an HDMI Monitor for an SBC

Though I spend the majority of my time working with microcontroller class devices, I also have an embarassingly robust collection of single board computers (SBC), including a few different Raspberry Pi models, the BeagleV Starlight Beta (RIP), and more. Typically when setting up these devices for whatever automation task I have planned for them, I’ll use “headless mode” and configure initial user and network credentials when writing the operating system to the storage device using a tool like Raspberry Pi’s Imager.

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Daniel Mangum 3 months ago

How AI on Microcontrollers Actually Works: Registering Operators

We started this series with a look at operators and kernels, the “instructions” used by models and the implementation of those instructions on the available hardware. We then explored the computation graph, which defines the sequence of operators for a given model, and explored how different model formats opt to include the explicit computation graph in the distributed file, or defer it to the inference application. With tflite-micro and the .

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Daniel Mangum 3 months ago

How AI on Microcontrollers Actually Works: The Computation Graph

In our last post we explored operators and kernels in Tensorflow Lite, and how the ability to swap out kernels depending on the hardware capabilities available can lead to dramatic performance improvements when performing inference. We made an analogy of operators to instruction set architectures (ISAs), and kernels to the hardware implementation of instructions in a processor. Just like in traditional computer programs, the sequence of instructions in a model needs to be encoded and distributed in some type of file, such as an Executable and Linkable Format (ELF) on Unix-based systems or Portable Executable (PE) on Windows.

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Daniel Mangum 3 months ago

How AI on Microcontrollers Actually Works: Operators and Kernels

The buzz around “edge AI”, which means something slightly different to almost everyone you talk to, is well past reaching a fever pitch. Regardless of what edge AI means to you, the one commonality is typically that the hardware on which inference is being performed is constrained in one or more dimensions, whether it be compute, memory, or network bandwidth. Perhaps the most constrained of these platforms are microcontrollers. I have found that, while there is much discourse around “running AI” (i.

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Daniel Mangum 8 months ago

Just Barely Fitting a Full Wi-Fi Stack on the nRF9151

In my last post on the Nordic Semiconductor Thingy:91 X IoT prototyping platform, I outlined the features and architecture of the device. The combination of wireless protocols on the Thingy:91 X (Bluetooth LE, LTE-M, Wi-Fi) make it a compelling foundation for a wide variety of applications. However, there are a few intricacies to the protocol support. Namely, the primary stated purpose of the Wi-Fi support is for network-based positioning (i.e. scan for local access points, send them to a server, get approximate location back).

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Daniel Mangum 8 months ago

Accessing the Qualcomm Modem over USB on the RAK5010

I have recently been working with the RAKwireless RAK5010 development board. It includes the popular Nordic nRF52840 MCU for running applications on its Cortex-M4 CPU that can leverage the integrated 2.4 GHz multiprotocol support, as well as the LTE and GNSS support offered by the on-board Quectel BG95-M3 module. The micro-USB port on the board is connected to USB on the nRF52840, which allows for viewing serial output, but is not a mechanism for flashing new firmware.

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Daniel Mangum 9 months ago

VPR: Arm and RISC-V Inter-Processor Communication

In our last post, we explored the Nordic VPR RISC-V processor through the lens of the peripheral processor (PPR) on the nRF54H20. While we demonstrated how the application processor can configure and start a VPR processor, we stopped short of demonstrating any further communication between them. Most meaningful use-cases of the PPR and the FLPR, involve communicating with the controlling processor. Nordic uses two different hardware peripherals for inter-processor communication (IPC) on the nRF54H20: VEVIF (VPR Event Interface) and BELLBOARD.

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Daniel Mangum 9 months ago

VPR: Nordic's First RISC-V Processor

VPR (pronounced “Viper”) is Nordic Semiconductor’s first RISC-V processor, landing in the new nRF54H and nRF54L lines of SoCs after their initial announcements in April and October of 2023 respectively. Readers of this blog are familiar with my long-running obsession interest in RISC-V (see my RISC-V Tips and RISC-V Bytes series). However, Nordic’s introduction of a RISC-V processor is particularly interesing to me as their lineup of microcontrollers is extremely popular in low power wireless domains, a common use case for Golioth customers.

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Daniel Mangum 10 months ago

USB UART on the Thingy:91 X

Nordic Semiconductor recently made their new IoT prototyping platform, the Thingy:91 X, generally available. The Thingy:91 X is an upgrade to their existing prototyping platform, the Thingy:91, replacing the nRF9160 System-in-Package (SiP) with an nRF9151 SiP, the nRF52840 System-on-Chip (SoC) with an nRF5340 SoC, and adding the nRF7002 integrated circuit (IC). Each of these components enables a different type of connectivity: nRF9151: cellular (LTE-M / NB-IoT), DECT NR+, GNSS nRF5340: Bluetooth LE, 802.

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Daniel Mangum 10 months ago

This Website is Hosted on Bluesky

Well, not this one. But this one is! How? Let’s take a closer look at Bluesky and the AT Protocol that underpins it. Note: I communicated with the Bluesky team prior to the publishing of this post. While the functionality described is not the intended use of the application, it is known behavior and does not constitue a vulnerability disclosure process. My main motivation for reaching out to them was because I like the folks and don’t want to make their lives harder.

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Daniel Mangum 11 months ago

USB On-The-Go on the ESP32-S3

The ESP32-S3 is a popular microcontroller (MCU) for a variety of reasons, such as its support for external pseudostatic RAM (PSRAM). One of its lesser known features is its Universal Serial Bus (USB) On-The-Go (OTG) controller. The previously released ESP32-S2, as well as the new ESP32-P4, also have USB OTG support, with the latter having two controllers. USB OTG devices can act as a device or as a host. This is a popular feature for smartphones, which, when attached to a laptop or desktop should act as a device, but may want to act as a host for some peripherals, such as a keyboard, that may be attached to it.

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Daniel Mangum 12 months ago

Is It Better to Fail Spectacularly?

Three weeks ago I wrote the following draft of a blog post entitled “Is It Better to Fail Spectacularly?”. I am having a lot of doubts. I’ve been training for the Chicago Marathon in earnest since June, but in reality the preparations began a year ago when I was accepted based on my qualifying time from the 2023 Ventura Marathon. I don’t have doubt that I can run a marathon. I have run three in the last year and a half, and I routinely go on weekend long runs that approach or surpass 20 miles.

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Daniel Mangum 1 years ago

The Taxonomy of Hardware Security Mechanisms

Isolating sensitive data and operations is a fundamental issue in computing. Ideally, we want to minimize the possibility of a software defect compromising the security of a device. However, in order for the software we write to be useful, it typically needs to interact with that sensitive data in some form or fashion. So how do we interact with sensitive data without being able to access it? The answer is that we bring only the operations that must access the sensitive data closer to the data, then force all other software to invoke those operations via some sort of interface.

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Daniel Mangum 1 years ago

Founder Mode for Non-Founders

Paul Graham’s Founder Mode essay, based on a recent talk from AirBnB founder Brian Chesky, has been getting quite a lot of attention over the past few days. It has prompted many a quote tweet, and founders, such as Bryan Cantrill of Oxide Computer, have started contributing their own thoughts to what founder mode means to them. Having held positions of influence at a few companies, but never having been a founder myself, my initial read raised a few thoughts about my own experience of trying to “scale myself” in a growing organization.

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Daniel Mangum 1 years ago

Static Allocation in External RAM on ESP32

I frequently work with ESP32 microcontrollers (MCU), both at my day job and in my free time. These devices are very flexible, but like any microcontroller they are quite resource constrained in comparison to anything equivalent to or larger than a single-board computer. There are a few different variants of the ESP32 these days, but one of the newer and most popular is the ESP32-S3. Compared to the ESP32-S2, it offers a dual-core 32-bit Xtensa processor, support for Bluetooth 5.

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Daniel Mangum 1 years ago

Wireframes are Cheap, Engineering Should Be Too

I have spent the majority of my career in engineering roles at startups. Both at companies I have worked at, and in the general startup ecosystem, I have frequently heard some variation of the refrain “engineers are expensive, but wireframes are cheap”. While I align with the underlying sentiment that doing the least amount of work to get customer signal is optimal, the phrase has always bothered me. As an engineering leader, I do not want the rest of the organization to view the work that my colleagues and I do as some luxury that should only be leveraged after we have reached complete confidence that a product or feature needs to be built.

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Daniel Mangum 1 years ago

The Most Important Skill in Startup Engineering Leadership

I have been very fortunate to have both worked alongside some incredible engineering leaders, as well as lead engineering teams myself. These experiences have primarily been in the context of startups that are growing rapidly in terms of both customers and employees. The longer I have worked in these environments, the more convinced I have become that there is a singular skill that ultimately decides the success of a leader, and thus their team: pacing.

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Daniel Mangum 1 years ago

RISC-V Bytes: Accessing the Pinecil UART with picoprobe

This post is the second in a RISC-V Bytes subseries on the PINE64 Pinecil soldering iron and development board. Previous and subsequent posts can be found under the RISC-V Bytes category. In the most recent Pinecil post, we walked through how to solder the header pins on the Pinecil breakout board. With the headers attached, we can now communicate with the Pinecil’s microcontroller via a number of protocols. Today we are going to focus on accessing the Universal Asynchronous Receiver / Transmitter (UART) hardware in order to receive serial data from the microcontroller, such as log messages, on a development machine (e.

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Daniel Mangum 1 years ago

RISC-V Bytes: Soldering the Pinecil Breakout Board

This post is the first in a RISC-V Bytes subseries on the PINE64 Pinecil soldering iron and development board. Subsequent posts can be found under the RISC-V Bytes category. I’ve been using the Pinecil as my primary soldering iron for a few months now. The neat thing about the Pinecil is that it is not only a highly portable USB-C powered iron, but it is also an interesting RISC-V development board.

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Daniel Mangum 1 years ago

Reflections on Running 3,000 Miles in 2023

I spent the final week of 2022 feeling extremely sick, mostly confined to a bed. I was particularly disappointed in getting sick at that point in the year given that I was wrapping up the best running year of my life. I was very consistent with training, ran a few races, and was closing in on 1,400 miles. I am a big proponent of setting ambitious goals, and will go to pretty extreme lengths to reach them.

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