Electrical UI’s Scott Rapson has been benchmarking numerous methods to attach microcontrollers wirelessly — aiming to seek out the hyperlink that gives the bottom latency empirically, reasonably than counting on knowledge sheets and artificial best-case situations.
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 seek out substantive details about latency past hand-wavy advertising and marketing superlatives,” Rapson explains. “Calculating image price and latency figures from radio first-principles is doable, however trendy radio chipsets are additionally topic to protocol particular behaviors and more and more complicated software program stacks.”
In the event you’ve ever questioned which wi-fi microcontroller delivers the bottom latency, this benchmark has the reply. (📷: Scott Rapson/Electrical UI)
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 assessments centered on a choice of commonly-used units: 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.
The Nordic nRF24 got here out a transparent winner, although Rapson recommends the Espressif ESP32-C6 as a smoother expertise. (📷: Scott Rapson/Electrical UI)
In brief: an honest checklist, masking “10k traces of code, a brand new yr, and […] an awesome >200 assessments throughout the totally 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 tasks, 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 stable selection for anybody seeking to construct low-latency IoT tasks, adopted by Nordic nRF elements “in case you can tolerate a steeper studying curve.”