8 November 2026 · Soldr
ESP32-C3 SuperMini: pinout, boot pins and what's official
Short answer: the SuperMini is a third-party board, so there's no official board pinout. Read the labels printed on your board. What is official is the ESP32-C3 chip itself: 3.0 to 3.6 V, single-core RISC-V up to 160 MHz, Wi-Fi and Bluetooth 5 (LE), and three strapping pins. GPIO9 low at reset (with GPIO8 high) enters download mode; GPIO9 high boots from flash. Keep parts that pull GPIO2, GPIO8 or GPIO9 off those pins.
The tiny ESP32-C3 SuperMini is popular because it's small and has the radio built in. It also confuses people, because many different pin diagrams circulate for it. Here's the honest version: what Espressif's ESP32-C3 datasheet says, and what you have to read from your own board. Our ESP32-C3 Super Mini reference page follows the same rule and doesn't publish a board pin table.
Why there's no official pinout
Espressif makes the ESP32-C3 chip and its own development boards. The SuperMini isn't one of them. The pin layout, the 5V pin, the USB-C connector and the board's size have no official source, so our reference page leaves them out instead of copying a diagram nobody can verify. Espressif's own DevKitM-1 is a different board with a different header, so its pinout doesn't apply either.
What to do: use the GPIO numbers printed on your board's silkscreen, and check them against the pin numbers in your code.
What the chip datasheet says
- Supply: 3.0 to 3.6 V (3.3 V typical). Never feed 5 V into a GPIO or the 3.3 V rail.
- Processor: 32-bit RISC-V, single core, up to 160 MHz. 400 KB SRAM.
- Radio: Wi-Fi 802.11 b/g/n (2.4 GHz) and Bluetooth 5 (LE).
- GPIO: 22 on the chip variant in the QFN32 package. Three of them are strapping pins, and on chip variants with flash inside the package, six are taken by that flash. That's why a small board breaks out fewer pins than the chip has.
- USB: the chip has a full-speed USB Serial/JTAG controller, so it can be programmed over USB without a separate USB-to-serial chip.
The boot pins
From the datasheet's boot mode table (Table 3-3):
- SPI boot (run your sketch): GPIO9 = 1. GPIO8 can be anything.
- Joint download boot (accept new firmware): GPIO8 = 1 and GPIO9 = 0.
- GPIO2 doesn't decide between the two, but the datasheet recommends keeping it pulled up, to avoid glitches.
Joint download boot accepts firmware over either the USB Serial/JTAG interface or the UART. So if an upload won't start, hold whatever pulls GPIO9 low on your board (often a button marked BOOT) while you reset or plug it in, then upload.
Practical rule: don't connect sensors, buttons or modules that pull GPIO2, GPIO8 or GPIO9 high or low at power-up. A board that boots fine on its own and fails with a part connected usually has the part on one of these.
Other things worth knowing
- Logic level: 3.3 V. 5 V sensors need a divider or level shifter. See 5 V sensors on a 3.3 V ESP32.
- Serial output: by default the chip's ROM prints its boot messages on both the UART and the USB Serial/JTAG interface, so you can see them over the same USB cable.
- Deep sleep: the datasheet gives 5 µA for the chip in deep sleep. The whole board draws more, because of its regulator and LED.
- Battery notes from listings (a VBAT pad and so on) are board details with no official source. Check your board before connecting a battery.
For the original ESP32's different boot pins, see ESP32 strapping pins. For upload errors, see "Wrong boot mode detected".
Using it in a build
Soldr builds for the ESP32-C3 and flashes common C3 boards from Chrome or Edge. When you describe a build, give the GPIO numbers from your board's labels if you've already wired something, say which pins your board's BOOT button and LED use if you know them, and check the pin list at the top of the sketch before wiring.
On Compoden: ESP32-C3 Super Mini. Describe your build on app.soldr.ai. Sign in and get 100 credits free.