The ESP32-C3 SuperMini

The smallest ESP32-C3 board in common use, and a blue LED wired the other way around from the DevKit's.

What it is

The same RISC-V chip as the ESP32-C3-DevKitM-1, at 160 MHz, on a board 22.5 by 18 mm with two rows of eight holes 0.6 inch apart, a USB-C socket, BOOT and RESET buttons, a red power LED, a blue LED and a ceramic antenna. The silkscreen numbers are the chip's GPIO numbers, so there is nothing to translate.

Pins

With the USB at the top, the left row reads 5, 6, 7, 8, 9, 10, 20 and 21, and the right row reads 5V, GND, 3V3, then 4, 3, 2, 1 and 0.

• GPIO 0 to 4 are the analog inputs, ADC1 channels 0 to 4.
• GPIO 20 and 21 are UART0's RX and TX.
• GPIO 8 and 9 are the chip's strapping pins. GPIO 9 is what BOOT grounds.
• 5V and 3V3 are supplies for the breadboard.

There is no RST hole: reset is the button.

The LED is the other way around

The blue LED is on GPIO 8, which is LED_BUILTIN, the same number as on the DevKitM-1. But here it is wired from 3.3 V through a resistor to the pin, so it lights when the pin is LOW. The DevKit's Blink runs, and the lamp is lit on the half of the cycle the DevKit's is dark. The SuperMini's own Blink says so, with an LED on GPIO 2 the ordinary way around to compare.

WiFi

It joins Mokxi's simulated network, with the network name and password as properties of the board. There is no radio, no 802.11 and no real internet: Simulated WiFi has the details.

What is modeled

The DevKitM-1 model's chip, whole: the core, GPIO and IO_MUX, UART0, the SYSTIMER, ADC1 and LEDC PWM. A pin with its internal pull-up switched on and nothing wired to it reads HIGH, so the BOOT button works on its own.

What is not modeled

The USB stack (Serial reaches the monitor directly), ADC2, Bluetooth, a real radio, and the regulator's limits. The blue LED's current is not drawn from the pin.

Starter project

SuperMini blink blinks the blue LED and an LED on GPIO 2 together, and they are always opposite: one lights on LOW, the other on HIGH.