A First Look at the ‘Beta’ ESP32-S2 Development Kits

Alasdair Allan
3 min readSep 22, 2019

Announced back in May by Espressif, engineering samples of the new ESP32-S2 silicon started shipping to community members in July. Since then both modules and beta developer kits have been making their way out into the community, and I recently managed to get my hands on one, an ESP32-S2 Beta-DevKitC V1.1.

Time for some quick first impressions?

ESP32-S2 Beta-DevKitC V1.1 on my desk. (📷: Alasdair Allan)

The new ESP32-S2 sits between the ESP8266 and the current ESP32 in the Espressif product line. Although far more powerful than the ESP8266, the new ESP32-S2 has only a single core to the original ESP32's two.

Whereas the ESP32 has a dual core Xtensa LX6 processor running at 240 MHz, the single core of the ESP32-S2 is a newer Tensilica Xtensa LX7. While it also runs at 240MHz the newer processors should be capable of more floating point operations per cycle, which may go some way to help to make up some of that difference. But for most people, the biggest change is the addition of USB support, with the ESP32-S2 offering support for full-speed USB OTG.

However the current engineering samples shipping to the community aren’t quite ready yet, and software support is still being developed ahead of the final ESP32-S2 release later in the year.

While the new ESP-S2 is now supported in a development branch of the ESP-IDF, the official Espressif development framework, there isn’t yet any support either for time-of-flight (ToF) measurements with normal Wi-Fi packets, or for full-speed USB OTG. There also isn’t any support for hardware security features, or the on chip cryptographic accelerator.

“ESP32-S2 has several dedicated hardware security features. Cryptographic accelerators are integrated, thus providing AES, SHA and RSA algorithms. Additional hardware security features are provided by the RNG, HMAC and Digital Signature modules, as well as flash encryption and secure boot signature verification. These characteristics allow the device to meet stringent security requirements.”

The absence of support at this point in the development process for the new hardware security features could be a big deal for anyone wanting to build a prototype around the new chip.

However going ahead and installing the pre-release toolchain on my MacBook I got things up and working fairly quickly, and was able to get some test code working on my development board without too much trouble. But right now the features I think we’re all interested in aren’t quite there yet.

While product makers are going to be looking hard those hardware security features, my own focus is on the ability to make ToF measurements for indoor positioning.

Since the arrival of Bluetooth LE, there have been a bunch of startups making attempts at using that for positioning, none have really been viable as doing accurate indoor positioning with BLE is just beyond what’s possible with the protocol.

Despite the recent arrival of Ultra-wideband (UWB) in the new Apple iPhone 11, like Bluetooth LE before it, it’s going to be quite a while before the ‘new’ standard becomes common enough that we can rely on it for positioning outside of a few magic tricks inside the heavily locked down Apple ecosphere.

Good support for ToF with standard Wi-Fi could be the answer to that problem, at least in the short to medium term, so I’m going to be watching the feature/esp32s2beta branch of the ESP-IDF to see how it gets rolled out.

The new ESP32-S2 looks like a solid addition to the Espressif range, with some interesting features, although firmware support for the most interesting is still in the works. While there isn’t any official news to pass on regarding either pricing, or production time lines, quite yet it looks like we’re getting pretty close. If you’ve been waiting for the ESP32-S2, it’s coming soon.