===============
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.

.. list-table::
   :align: center

   * - .. figure:: ESP32-C3-DevKitC-02-v1.1.png
          :align: center

          ESP32-C3-DevKitC-02

     - .. figure:: ESP32-C3-DevKitM-1-v1.0.png
          :align: center

          ESP32-C3-DevKitM-1

Buttons and LEDs
================

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.

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
==============

nsh
---

Basic configuration to run the NuttShell (nsh).

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/gpout0
  nsh> gpio -o 1 /dev/gpout1

  nsh> gpio -o 0 /dev/gpout0
  nsh> gpio -o 0 /dev/gpout1

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

    nsh> gpio -w 14 /dev/gpint2

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

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.

watcher
-------

This configuration tests the watchdog timers in the capture mode.
It includes the 2 MWDTS, adds driver support, registers the WDTs as devices
and includes the watcher and watched example applications.

To test it, just run the following command::

  nsh> watcher
  nsh> watched

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