ESP32-C3 DevKit

The ESP32-C3 DevKit is an entry-level development board equipped with either an ESP32-C3-WROOM-02 or an ESP32-C3-MINI-1. ESP32-C3-WROOM-02 and ESP32-C3-MINI-1 are SoMs based on the RISC-V ESP32-C3 CPU.

Most of the I/O pins are broken out to the pin headers on both sides for easy interfacing. Developers can either connect peripherals with jumper wires or mount ESP32-C3 DevKit on a breadboard.

ESP32-C3-DevKitC-02

ESP32-C3-DevKitM-1

Buttons and LEDs

Board Buttons

There are two buttons labeled Boot and RST. The RST button is not available to software. It pulls the chip enable line that doubles as a reset line.

The BOOT button is connected to IO9. On reset it is used as a strapping pin to determine whether the chip boots normally or into the serial bootloader. After reset, however, the BOOT button can be used for software input.

Board LEDs

There is one on-board LED that indicates the presence of power. Another WS2812 LED is connected to GPIO8 and is available for software.

Configurations

All of the configurations presented below can be tested by running the following commands:

$ ./tools/configure.sh esp32c3-generic:<config_name>
$ make flash ESPTOOL_PORT=/dev/ttyUSB0 -j

Where <config_name> is the name of board configuration you want to use, i.e.: nsh, buttons, wifi… Then use a serial console terminal like picocom configured to 115200 8N1.

bmp180

This configuration enables the use of the BMP180 pressure sensor over I2C. You can check that the sensor is working by using the bmp180 application:

nsh> bmp180
Pressure value = 91531
Pressure value = 91526
Pressure value = 91525

coremark

This configuration sets the CoreMark benchmark up for running on the maximum number of cores for this system. It also enables some optimization flags and disables the NuttShell to get the best possible score.

Note

As the NSH is disabled, the application will start as soon as the system is turned on.

gpio

This is a test for the GPIO driver. It uses GPIO1 and GPIO2 as outputs and GPIO9 as an interrupt pin.

At the nsh, we can turn the outputs on and off with the following:

nsh> gpio -o 1 /dev/gpio0
nsh> gpio -o 1 /dev/gpio1

nsh> gpio -o 0 /dev/gpio0
nsh> gpio -o 0 /dev/gpio1

We can use the interrupt pin to send a signal when the interrupt fires:

nsh> gpio -w 14 /dev/gpio2

The pin is configured as a rising edge interrupt, so after issuing the above command, connect it to 3.3V.

i2c

This configuration can be used to scan and manipulate I2C devices. You can scan for all I2C devices using the following command:

nsh> i2c dev 0x00 0x7f

nsh

Basic configuration to run the NuttShell (nsh).

ostest

This is the NuttX test at apps/testing/ostest that is run against all new architecture ports to assure a correct implementation of the OS.

pwm

This configuration demonstrates the use of PWM through a LED connected to GPIO2. To test it, just execute the pwm application:

nsh> pwm
pwm_main: starting output with frequency: 10000 duty: 00008000
pwm_main: stopping output

rmt

This configuration configures the transmitter and the receiver of the Remote Control Transceiver (RMT) peripheral on the ESP32-C3 using GPIOs 8 and 2, respectively. The RMT peripheral is better explained here, in the ESP-IDF documentation. The minimal data unit in the frame is called the RMT symbol, which is represented by rmt_item32_t in the driver:

The example rmtchar can be used to test the RMT peripheral. Connecting these pins externally to each other will make the transmitter send RMT items and demonstrates the usage of the RMT peripheral:

nsh> rmtchar

WS2812 addressable RGB LEDs

This same configuration enables the usage of the RMT peripheral and the example ws2812 to drive addressable RGB LEDs:

nsh> ws2812

Please note that this board contains an on-board WS2812 LED connected to GPIO8 and, by default, this config configures the RMT transmitter in the same pin.

rtc

This configuration demonstrates the use of the RTC driver through alarms. You can set an alarm, check its progress and receive a notification after it expires:

nsh> alarm 10
alarm_daemon started
alarm_daemon: Running
Opening /dev/rtc0
Alarm 0 set in 10 seconds
nsh> alarm -r
Opening /dev/rtc0
Alarm 0 is active with 10 seconds to expiration
nsh> alarm_daemon: alarm 0 received

spi

This configuration enables the support for the SPI driver. You can test it by connecting MOSI and MISO pins which are GPIO7 and GPIO2 by default to each other and running the spi example:

nsh> spi exch -b 2 "AB"
Sending:    AB
Received:   AB

spiflash

This config tests the external SPI that comes with the ESP32-C3 module connected through SPI1.

By default a SmartFS file system is selected. Once booted you can use the following commands to mount the file system:

nsh> mksmartfs /dev/smart0
nsh> mount -t smartfs /dev/smart0 /mnt

sta_softap

With this configuration you can run these commands to be able to connect your smartphone or laptop to your board:

nsh> ifup wlan1
nsh> dhcpd_start wlan1
nsh> wapi psk wlan1 mypasswd 3
nsh> wapi essid wlan1 nuttxap 1

In this case, you are creating the access point nuttxapp in your board and to connect to it on your smartphone you will be required to type the password mypasswd using WPA2.

Tip

Please refer to ESP32 Wi-Fi SoftAP Mode for more information.

The dhcpd_start is necessary to let your board to associate an IP to your smartphone.

timer

This config test the general use purpose timers. It includes the 4 timers, adds driver support, registers the timers as devices and includes the timer example.

To test it, just run the following:

nsh> timer -d /dev/timerx

Where x in the timer instance.

twai

This configuration enables the support for the TWAI (Two-Wire Automotive Interface) driver. You can test it by connecting TWAI RX and TWAI TX pins which are GPIO0 and GPIO2 by default to an external transceiver or connecting TWAI RX to TWAI TX pin by enabling the CONFIG_CAN_LOOPBACK option (Device Drivers -> CAN Driver Support -> CAN loopback mode) and running the can example:

nsh> can
nmsgs: 0
min ID: 1 max ID: 2047
Bit timing:
  Baud: 1000000
  TSEG1: 15
  TSEG2: 4
    SJW: 3
  ID:    1 DLC: 1

usbconsole

This configuration tests the built-in USB-to-serial converter found in ESP32-C3 (revision 3). esptool can be used to check the version of the chip and if this feature is supported. Running esptool.py -p <port> chip_id should have Chip is ESP32-C3 (revision 3) in its output. When connecting the board a new device should appear, a /dev/ttyACMX on Linux or a /dev/cu.usbmodemXXX om macOS. This can be used to flash and monitor the device with the usual commands:

make download ESPTOOL_PORT=/dev/ttyACM0
minicom -D /dev/ttyACM0

watchdog

This configuration tests the watchdog timers. It includes the 2 MWDTS, adds driver support, registers the WDTs as devices and includes the watchdog example application.

To test it, just run the following command:

nsh> wdog -i /dev/watchdogX

Where X is the watchdog instance.

To test the XTWDT(/dev/watchdog3) an interrupt handler needs to be implemented because XTWDT does not have system reset feature. To implement an interrupt handler WDIOC_CAPTURE command can be used. When interrupt rises, XTAL32K clock can be restored with WDIOC_RSTCLK command.

wifi

Enables Wi-Fi support. You can define your credentials this way:

$ make menuconfig
-> Application Configuration
    -> Network Utilities
        -> Network initialization (NETUTILS_NETINIT [=y])
            -> WAPI Configuration

Or if you don’t want to keep it saved in the firmware you can do it at runtime:

nsh> wapi psk wlan0 mypasswd 3
nsh> wapi essid wlan0 myssid 1
nsh> renew wlan0

Tip

Please refer to ESP32 Wi-Fi Station Mode for more information.