Scott Rapson’s Exhaustive Testing Finds the Best, Lowest-Latency Wi-fi Microcontrollers

Electrical UI’s Scott Rapson has been benchmarking varied methods to attach microcontrollers wirelessly — aiming to search out the hyperlink that gives the bottom latency empirically, somewhat than counting on information sheets and artificial best-case eventualities.

Whereas requirements teams, radio chipset distributors, and IoT [Internet of Things] system integrators fortunately discuss enhancements to bandwidth, long-range capabilities, or how low their energy consumption is, I’ve actually struggled to search out substantive details about latency past hand-wavy advertising superlatives,” Rapson explains. “Calculating image fee and latency figures from radio first-principles is doable, however fashionable radio chipsets are additionally topic to protocol particular behaviors and more and more complicated software program stacks.”

The answer, then, is to assault the issue in the actual world: getting a bunch of microcontrollers with radio transceivers and placing them head-to-head to see which delivers the bottom latency for uni-directional consumer interplay duties — assume “switching on a lightbulb” or “controlling a robotic’s actuators.”

Rapson’s checks targeted on a choice of commonly-used gadgets: Silicon Labs RF+8051 operating the SiK firmware, a HopeRF RFM95W with its Semtech SX1276 connecting over LoRa, the Nordic nRF24L01 connecting over 2.4Ghz, its nRF52850 operating over the Nordic UART Bridge Service and Bluetooth Low Vitality, the Espressif ESP32 connecting over ESP-NOW, Wi-Fi, IEEE 802.15.4, Bluetooth Low Vitality with each Bluedroid and NimBLE, and Bluetooth Traditional, HC-05/06 modules connecting over Bluetooth Traditional, and the Raspberry Pi 4 Mannequin B connecting over Wi-Fi.

In brief: an honest record, overlaying “10k traces of code, a brand new 12 months, and […] an amazing >200 checks throughout the completely different targets,” Rapson writes. And the conclusion? A transparent win for the Nordic nRF24 module: “it recorded the bottom minimal, decrease/higher quartile, and median [latency] for 12B and 128B payloads.

“The simplest implementation was the ESP32-C6 with IEEE 802.15.4, adopted by the clear UART bridges SiK and HC-05, and ESP-NOW,” Rapson continues. “Essentially the most irritating work was troubleshooting the NimBLE stack on the ESP32. The right storm of sub-par default efficiency, stale instance initiatives, and needing to repeatedly cross-reference between the Espressif and MyNewt documentation web sites and source-code.”

Rapson’s full, exhaustive write-up is accessible on the Electrical UI web site, and concludes with the recommendation that the Espressif ESP32-C6 is a strong selection for anybody trying to construct low-latency IoT initiatives, adopted by Nordic nRF components “in the event you can tolerate a steeper studying curve.”