ESP32-C3 Board

ESP32-C3 is a system on a chip that integrates the following features:

Wi-Fi (2.4 GHz band)
Bluetooth Low Energy
High performance 32-bit RISC-V-ish single-core processor
Multiple peripherals
Built-in security hardware

Powered by 40 nm technology, ESP32-C3 provides a robust, highly integrated platform, which helps meet the continuous demands for efficient power usage, compact design, security, high performance, and reliability.

Setup

Install the ESP tool:

shell

# macOS
brew install esptool

of from source:

shell

git clone https://github.com/espressif/esptool.git
cd esptool
pip install --user -e .

The first time you are installing Tock you probably want to erase the flash first. This can be done with:

shell

esptool.py --chip esp32c3 erase_flash

After that you can run:

shell

make init
make flash

To install Tock.

You can then connect to the serial device exposed from the USB header on the board.

You can use the RST button on the board to reset Tock. You should see something similar to:

text

ESP-ROM:esp32c3-20200918
Build:Sep 18 2020
rst:0x1 (POWERON),boot:0xc (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:1
load:0x40380000,len:0xd15c
load:0x4038d15c,len:0xccc
load:0x00000000,len:0x21a0
load:0x42000000,len:0x24
SHA-256 comparison failed:
Calculated: 63cf02fff6c0e3f60d140721bbd74adf0072c368b3bfafb6d4195511a55ba8c9
Expected: f4494a64f93940e1bb4d0edce76f041e6a411337097c697b254b784af1e2bcd5
Attempting to boot anyway...
entry 0x40380000
ESP32-C3 initialisation complete.
Entering main loop.

shell

screen /dev/ttyUSB0  115200

Building and Flashing Applications

Apps are built out-of-tree, for example:

bash

$ cd libtock-c/examples/<app>
$ make

To "flash" an app, we first write it to a binary file that is combined with the kernel which we will write in its entirety to the board.

bash

$ tockloader install --local-board

Then to flash the kernel with the app:

$ cd tock/boards/esp32-c3-devkitM-1
$ make flash

JTAG Debugging

In order to use JTAG debugging you first need to build a fork of OpenOCD

shell

git clone https://github.com/espressif/openocd-esp32
cd openocd-esp32
./bootstrap
./configure --disable-werror
make -j8

Note that the connection can be unreliable, commit 5b67ad1b15938f524f133afb8ef652c990f570eb seems to work though.

Then connect an FTDI C232HM cable as described here: https://docs.espressif.com/projects/esp-idf/en/latest/esp32c3/api-guides/jtag-debugging/configure-other-jtag.html.

Make sure that the board is powered by the JTAG and that the usual USB connection is unplugged when doing JTAG debugging.

Then run OpenOCD

shell

./src/openocd -s tcl -f tcl/board/esp32c3-ftdi.cfg

Then connect from GDB

shell

target remote :3333
set remote hardware-watchpoint-limit 2
set mem inaccessible-by-default off