Unexpected Maker ProS2 Packs ESP32-S2 Power Into a Compact, Breadboard-Friendly Design

All the power of the Espressif ESP32-S2 microcontroller, but from a board considerably more compact than the company's own development kit.

Seon Rozenblum, the Unexpected Maker, has unveiled his latest creation: The first third-party board based on the Espressif ESP32-S2 microcontroller, following the release of Espressif's own beta-status development kits late last month — complete with a video of the board being assembled.

The Unexpected Maker ProS2 is the smallest ESP32-S2 board yet. (📷 Unexpected Maker)

Dubbed the ProS2, Rozenblum's breadboard-friendly design is considerably more compact than Espressif's own development board. As well as the ESP32-S2 microcontroller itself, the design incorporates 16MB of flash memory, 8MB of pseudo-static RAM (PSRAM), two 700mA low-dropout regulators (LDOs) driving both the 3V3 circuitry and a dedicated 3V3 output pin, a built-in charging circuit for Lithium Polymer (LiPo) batteries, an on-board Fractus antenna, boot and reset buttons, and a programmable RGB LED.

The dual-LDO design offers some major advantages over a single-LDO layout, too. "[The second LDO] only drives the APA [LED] and also has a [3V3] out over here," Rozenblum explains in his video presentation. "That way you're not pinching needed current capabilities from the onboard LDO that drives the ESP32 or the other peripherals, and it also means that you can control the power on and off state via that LDO with the enable pin via both GPIO21 and the deep-sleep state of the ESP32-S2. So, if the ESP32-S2 goes to sleep, if you put it to sleep, it will automatically shut down power to that second LDO, so anything connected to it will power down automatically. But, if the ESP32-S2 is awake, then you can control whether the power's turned on or off via GPIO21."

The core ESP32-S2 microcontroller offers the same capabilities, meanwhile, as on Espressif's own development board design: A single-core 32-bit Xtensa LX7 processor running at up to 240MHz, 43 total general-purpose input/outputs (GPIOs), 320kB of SRAM, 128kB ROM, and 16kB RTC memory, 2.4GHz 802.11b/g/n Wi-Fi connectivity with support for the HT40 mode for up to 150Mbps data throughput, and a 4,096-bit eFUSE secure memory of which 2,048 bits are available for application use.

The board is aimed at the professional user, Rozenblum says, warning that it's not likely to come in below the cost of the first units to arrive from China once the ESP32-S2 hits wider general availability. It is, however, optimised both for low power and for footprint.

Thus far, Rozenblum has not commented on likely pricing or scheduled availability for the boards, advising that a second unit will need to be assembled and sent off for radio-frequency testing to perform antenna matching before the design can be considered finalised. A video demonstrating the first assembled board in action is scheduled to be published on the Unexpected Maker YouTube channel in the near future, while Rozenblum's earlier designs can be found in his Tindie store.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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