The Abbycus QDEV-ESP32-C3 development board is an Internet Of Things (IOT) development module based on the Espressif ESP32-C3-WROOM-02 module.

The QDEV-ESP32-C3 is a powerful and cost effective development/product ready platform with a 'dongle' style form factor which incorporates a male USB-A connector allowing the board to be powered and programmed via a standard USB-Serial port. Additionally the user application can use the Serial port to communicate with a host PC, laptop, Raspberry Pi, etc.

The board also has full support for a 3.7V Lithium Ion battery using a high efficiency buck/boost regulator and charging circuitry. See below for more battery information.

For project examples see here. These examples are written for the ESP8266 but should work with other Espressif variants. Note that the 'ESP8266WiFi.h' library will need to be changed to 'WiFi.h'.

• Espressif ESP32-C3 32 bit RISC-V single core low power MCU.
• 80 / 160 Mhz CPU clock speed.
• 384 KBytes of SRAM.
• 4 MBytes of flash memory.
• WiFi module supports IEEE802.11 b/g/n protocol w/embedded TCPIP stack.
• WiFi supports adhoc and MESH networks based on ESP-NOW protocol.
• Bluetooth LE: Bluetooth 5.0, Bluetooth MESH, Bluetooth long range.
• Integrated Inverted F PCB antenna.
• 6 channels of 12-bit Analog to Digital converter (ADC).
• 13 GPIO's available with PWM and low power wakeup capability.
• UART supporting baud rates up to 5 Mbaud.
• Auto-programming circuit (eliminates the need for a 'boot' button).
• On-board user LED (IO9).
• High efficiency buck/boost switching regulator yields >90% efficiency for maximum battery life.
• Battery reverse polarity protection.
• Auto-Resettable polyfuse.
• Integrated battery charge circuit with charge state LED.
• Default charge current of 250 milliamps can be modified via an onboard resistor.
• Power on/off switch.
• Reset button.

The board is normally powered by 5 volts via the USB-A connector. The 5 volt input is regulated down to 3.3 volts using a high efficency buck/boost switching regulator.

The 3.3 volt breakout pin can supply power to external circuits with a maximum current of 600 milliamps.

WARNING: The ESP32-C3 is not 5V tolerant. Voltage applied to any I/O pin should not exceed 3.3V.

The board can be powered by an external 3.7V Lithium Ion battery connected to the BAT terminals. The embedded buck/boost switching regulator maintains a stable 3.3V system voltage from a battery voltage of 4.2V (full charge) down to approximately 2.5V (discharged). The battery is charged when 5 volts is applied via the USB-A connector. The on-board RED LED will light while charging and turn off when charging is complete.

Default charge current is set at 250 milliamps. This can be changed by replacing resistor R11 on the PCB. See the AAP2154 (LTC4054 equivalent) datasheet in the DOCS folder for information regarding setting the charge current.

Operating current can range from microamps in deep sleep mode to peaks of approximately 160 milliamps when transmitting WiFi data. Typical idle current is approximately 50 milliamps.

• 3.3V Output of the 3.3V switching regulator.

• NRST MCU reset - active low.

• IO4 GPIO4 / ADC1_CH4 / FSPIHD / MTMS.

• IO5 GPIO5 / ADC2_CH0 / FSPIWP / MTDI.

• IO6 GPIO6 / FSPICLK / MTCK.

• IO7 GPIO7 / FSPID / MTDO.

• IO8 GPIO8. STRAPPING PIN

• IO9 GPIO9. STRAPPING PIN

• GND Board ground connect.

• IO10 GPIO / FSPICS0.

• RXD0 UART0_RXD / GPIO20.

• TXD0 UART0_TXD / GPIO21.

• IO18 GPIO18 / USB_D-.

• IO19 GPIO19 / USB_D+.

• IO3 GPIO3 / ADC1_CH3.

• IO2 GPIO2 / ADC1_CH2 / FSPIQ. STRAPPING PIN

• IO1 GPIO1 / ADC1_CH1 / XTAL_32K_N.

• IO0 GPIO0 / ADC1_CH0 / XTAL_32K_P.

Three GPIO pins are used by the ESP32-C3 to control boot mode. The pin level during boot is as follows:

• IO2 UART download mode: pulldown. Normal boot from flash: floating or pullup.
• IO8 UART download mode: floating or pullup. Normal boot from flash: don't care.
• IO9 UART download mode: pulldown. Normal boot from flash: floating or pullup.

The QDEV-ESP32-C3 is programmed through the USB-A connector.

The QDEV-ESP32-C3 can function as a UART bridge between two or more computers.

Firmware can be developed on several platforms such as the Arduino IDE, PlatformIO on VSCode, or the Espressif ESP-IDF development environment. The code examples included here were written using the Arduino framework on PlatformIO IDE.

While the Arduino IDE is relatively simple, the advanced features of PlatformIO make it much more compelling and useful to developers.

The Espressif ESP-IDF offers more detailed control of certain features but lacks the rich library support of either the Arduino IDE or PlatformIO and is specific to Espressif devices.

The QDEV-ESP32-C3 board also supports microPython.