| ================== |
| Espressif ESP32-C3 |
| ================== |
| |
| The ESP32-C3 is an ultra-low-power and highly integrated SoC with a RISC-V |
| core and supports 2.4 GHz Wi-Fi and Bluetooth Low Energy. |
| |
| * Address Space |
| - 800 KB of internal memory address space accessed from the instruction bus |
| - 560 KB of internal memory address space accessed from the data bus |
| - 1016 KB of peripheral address space |
| - 8 MB of external memory virtual address space accessed from the instruction bus |
| - 8 MB of external memory virtual address space accessed from the data bus |
| - 480 KB of internal DMA address space |
| * Internal Memory |
| - 384 KB ROM |
| - 400 KB SRAM (16 KB can be configured as Cache) |
| - 8 KB of SRAM in RTC |
| * External Memory |
| - Up to 16 MB of external flash |
| * Peripherals |
| - 35 peripherals |
| * GDMA |
| - 7 modules are capable of DMA operations. |
| |
| ESP32-C3 Toolchain |
| ================== |
| |
| A generic RISC-V toolchain can be used to build ESP32-C3 projects. |
| SiFive's toolchain can be downloaded from: https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz |
| |
| Second stage bootloader and partition table |
| =========================================== |
| |
| The NuttX port for now relies on IDF's second stage bootloader to carry on some hardware |
| initializations. The binaries for the bootloader and the partition table can be found in |
| this repository: https://github.com/espressif/esp-nuttx-bootloader |
| That repository contains a dummy IDF project that's used to build the bootloader and |
| partition table, these are then presented as Github assets and can be downloaded |
| from: https://github.com/espressif/esp-nuttx-bootloader/releases |
| Download ``bootloader-esp32c3.bin`` and ``partition-table-esp32c3.bin`` and place them |
| in a folder, the path to this folder will be used later to program them. This |
| can be: ``../esp-bins`` |
| |
| Building and flashing |
| ===================== |
| |
| First make sure that ``esptool.py`` is installed. This tool is used to convert |
| the ELF to a compatible ESP32 image and to flash the image into the board. |
| It can be installed with: ``pip install esptool``. |
| |
| Configure the NUttX project: ``./tools/configure.sh esp32c3-devkit:nsh`` |
| Run ``make`` to build the project. Note that the conversion mentioned above is |
| included in the build process. |
| The `esptool.py` command to flash all the binaries is:: |
| |
| esptool.py --chip esp32c3 --port /dev/ttyUSBXX --baud 921600 write_flash 0x0 bootloader.bin 0x8000 partition-table.bin 0x10000 nuttx.bin |
| |
| However, this is also included in the build process and we can build and flash with:: |
| |
| make download ESPTOOL_PORT=<port> ESPTOOL_BINDIR=../esp-bins |
| |
| Where ``<port>`` is typically ``/dev/ttyUSB0`` or similar and ``../esp-bins`` is |
| the path to the folder containing the bootloader and the partition table |
| for the ESP32-C3 as explained above. |
| Note that this step is required only one time. Once the bootloader and partition |
| table are flashed, we don't need to flash them again. So subsequent builds |
| would just require: ``make download ESPTOOL_PORT=/dev/ttyUSBXX`` |
| |
| Debugging with OpenOCD |
| ====================== |
| |
| Download and build OpenOCD from Espressif, that can be found in |
| https://github.com/espressif/openocd-esp32 |
| |
| If you have an ESP32-C3 ECO3, no external JTAG is required to debug, the ESP32-C3 |
| integrates a USB-to-JTAG adapter. |
| |
| OpenOCD can then be used:: |
| |
| openocd -c 'set ESP_RTOS none' -f board/esp32c3-builtin.cfg |
| |
| For versions prior to ESP32-C3 ECO3, an external JTAG adapter is needed. |
| It can be connected as follows:: |
| |
| TMS -> GPIO4 |
| TDI -> GPIO5 |
| TCK -> GPIO6 |
| TDO -> GPIO7 |
| |
| Furthermore, an efuse needs to be burnt to be able to debug:: |
| |
| espefuse.py -p <port> burn_efuse DIS_USB_JTAG |
| |
| OpenOCD can then be used:: |
| |
| openocd -c 'set ESP_RTOS none' -f board/esp32c3-ftdi.cfg |
| |
| Peripheral Support |
| ================== |
| |
| The following list indicates the state of peripherals' support in NuttX: |
| |
| ========== ======= ===== |
| Peripheral Support NOTES |
| ========== ======= ===== |
| GPIO Yes |
| UART Yes |
| SPI Yes |
| I2C Yes |
| DMA Yes |
| Wifi Yes |
| SPIFLASH Yes |
| Timers Yes |
| Watchdog Yes |
| RTC Yes |
| RNG Yes |
| AES Yes |
| eFuse Yes |
| ADC Yes |
| Bluetooth Yes |
| LED_PWM Yes |
| SHA Yes |
| RSA Yes |
| ========== ======= ===== |
| |
| |
