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I am a principal software engineer at Upbound.
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VPR: Arm and RISC-V Inter-Processor Communication

2024-12-31 15:41:34

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.

VPR: Nordic's First RISC-V Processor

2024-12-24 15:41:34

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.

USB UART on the Thingy:91 X

2024-12-15 15:41:34

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.

This Website is Hosted on Bluesky

2024-11-24 15:41:34

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.

USB On-The-Go on the ESP32-S3

2024-11-11 15:41:34

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.

Is It Better to Fail Spectacularly?

2024-10-20 15:41:34

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.