Espressif ESP32-C6
The ESP32-C6 is an ultra-low-power and highly integrated SoC with a RISC-V core and supports 2.4 GHz Wi-Fi 6, Bluetooth 5 (LE) and the 802.15.4 protocol.
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 - 320 KB ROM - 512 KB SRAM (16 KB can be configured as Cache) - 16 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-C6 Toolchain
A generic RISC-V toolchain can be used to build ESP32-C6 projects. It’s recommended to use the same toolchain used by NuttX CI. Please refer to the Docker container and check for the current compiler version being used. For instance:
###############################################################################
# Build image for tool required by RISCV builds
###############################################################################
FROM nuttx-toolchain-base AS nuttx-toolchain-riscv
# Download the latest RISCV GCC toolchain prebuilt by xPack
RUN mkdir riscv-none-elf-gcc && \
curl -s -L "https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases/download/v13.2.0-2/xpack-riscv-none-elf-gcc-13.2.0-2-linux-x64.tar.gz" \
| tar -C riscv-none-elf-gcc --strip-components 1 -xz
It uses the xPack’s prebuilt toolchain based on GCC 13.2.0-2.
Installing
First, create a directory to hold the toolchain:
$ mkdir -p /path/to/your/toolchain/riscv-none-elf-gcc
Download and extract toolchain:
$ curl -s -L "https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack/releases/download/v13.2.0-2/xpack-riscv-none-elf-gcc-13.2.0-2-linux-x64.tar.gz" \
| tar -C /path/to/your/toolchain/riscv-none-elf-gcc --strip-components 1 -xz
Add the toolchain to your PATH:
$ echo "export PATH=/path/to/your/toolchain/riscv-none-elf-gcc/bin:$PATH" >> ~/.bashrc
You can edit your shell’s rc files if you don’t use bash.
Building and flashing NuttX
Installing esptool
First, make sure that esptool.py
is installed and up-to-date.
This tool is used to convert the ELF to a compatible ESP32-C6 image and to flash the image into the board.
It can be installed with: pip install esptool>=4.8.1
.
Warning
Installing esptool.py
may required a Python virtual environment on newer systems.
This will be the case if the pip install
command throws an error such as:
error: externally-managed-environment
.
If you are not familiar with virtual environments, refer to Managing esptool on virtual environment for instructions on how to install esptool.py
.
Bootloader and partitions
NuttX can boot the ESP32-C6 directly using the so-called “Simple Boot”.
An externally-built 2nd stage bootloader is not required in this case as all
functions required to boot the device are built within NuttX. Simple boot does not
require any specific configuration (it is selectable by default if no other
2nd stage bootloader is used). For compatibility among other SoCs and future options
of 2nd stage bootloaders, the commands make bootloader
and the ESPTOOL_BINDIR
option (for the make flash
) are kept (and ignored if Simple Boot is used).
If other features are required, an externally-built 2nd stage bootloader is needed.
The bootloader is built using the make bootloader
command. This command generates
the firmware in the nuttx
folder. The ESPTOOL_BINDIR
is used in the
make flash
command to specify the path to the bootloader. For compatibility
among other SoCs and future options of 2nd stage bootloaders, the commands
make bootloader
and the ESPTOOL_BINDIR
option (for the make flash
)
can be used even if no externally-built 2nd stage bootloader
is being built (they will be ignored if Simple Boot is used, for instance):
$ make bootloader
Note
It is recommended that if this is the first time you are using the board with NuttX to perform a complete SPI FLASH erase.
$ esptool.py erase_flash
Building and Flashing
This is a two-step process where the first step converts the ELF file into an ESP32-C6 compatible binary and the second step flashes it to the board. These steps are included in the build system and it is possible to build and flash the NuttX firmware simply by running:
$ make flash ESPTOOL_PORT=<port> ESPTOOL_BINDIR=./
where:
ESPTOOL_PORT
is typically/dev/ttyUSB0
or similar.ESPTOOL_BINDIR=./
is the path of the externally-built 2nd stage bootloader and the partition table (if applicable): when built using themake bootloader
, these files are placed intonuttx
folder.ESPTOOL_BAUD
is able to change the flash baud rate if desired.
Flashing NSH Example
This example shows how to build and flash the nsh
defconfig for the ESP32-C6-DevKitC-1 board:
$ cd nuttx
$ make distclean
$ ./tools/configure.sh esp32c6-devkitc:nsh
$ make -j$(nproc)
When the build is complete, the firmware can be flashed to the board using the command:
$ make -j$(nproc) flash ESPTOOL_PORT=<port> ESPTOOL_BINDIR=./
where <port>
is the serial port where the board is connected:
$ make flash ESPTOOL_PORT=/dev/ttyUSB0 ESPTOOL_BINDIR=./
CP: nuttx.hex
MKIMAGE: NuttX binary
esptool.py -c esp32c6 elf2image --ram-only-header -fs 4MB -fm dio -ff 80m -o nuttx.bin nuttx
esptool.py v4.8.1
Creating esp32c6 image...
Image has only RAM segments visible. ROM segments are hidden and SHA256 digest is not appended.
Merged 1 ELF section
Successfully created esp32c6 image.
Generated: nuttx.bin
esptool.py -c esp32c6 -p /dev/ttyUSB0 -b 921600 write_flash -fs 4MB -fm dio -ff 80m 0x0000 nuttx.bin
esptool.py v4.8.1
Serial port /dev/ttyUSB0
Connecting....
Chip is ESP32-C6 (QFN40) (revision v0.0)
[...]
Flash will be erased from 0x00000000 to 0x0003cfff...
Compressed 248628 bytes to 106757...
Wrote 248628 bytes (106757 compressed) at 0x00000000 in 2.5 seconds (effective 805.6 kbit/s)...
Hash of data verified.
Leaving...
Hard resetting via RTS pin...
Now opening the serial port with a terminal emulator should show the NuttX console:
$ picocom -b 115200 /dev/ttyUSB0
NuttShell (NSH) NuttX-12.8.0
nsh> uname -a
NuttX 12.8.0 759d37b97c-dirty Mar 5 2025 19:42:41 risc-v esp32c6-devkitc
Debugging
This section describes debugging techniques for the ESP32-C6.
Debugging with openocd
and gdb
Espressif uses a specific version of OpenOCD to support ESP32-C6: openocd-esp32.
Please check Building OpenOCD from Sources for more information on how to build OpenOCD for ESP32-C6.
You do not need an external JTAG to debug, the ESP32-C6 integrates a USB-to-JTAG adapter.
Note
One must configure the USB drivers to enable JTAG communication. Please check Configure USB Drivers for more information.
OpenOCD can then be used:
openocd -s <tcl_scripts_path> -c 'set ESP_RTOS hwthread' -f board/esp32c6-builtin.cfg -c 'init; reset halt; esp appimage_offset 0x0'
Note
appimage_offset
should be set to0x0
whenSimple Boot
is used. For MCUboot, this value should be set toCONFIG_ESPRESSIF_OTA_PRIMARY_SLOT_OFFSET
value (0x10000
by default).-s <tcl_scripts_path>
defines the path to the OpenOCD scripts. Usually set to tcl if running openocd from its source directory. It can be omitted if openocd-esp32 were installed in the system with sudo make install.
If you want to debug with an external JTAG adapter it can be connected as follows:
ESP32-C6 Pin |
JTAG Signal |
---|---|
GPIO4 |
TMS |
GPIO5 |
TDI |
GPIO6 |
TCK |
GPIO7 |
TDO |
Furthermore, an efuse needs to be burnt to be able to debug:
espefuse.py -p <port> burn_efuse DIS_USB_JTAG
Warning
Burning eFuses is an irreversible operation, so please consider the above option before starting the process.
OpenOCD can then be used:
openocd -c 'set ESP_RTOS hwtread; set ESP_FLASH_SIZE 0' -f board/esp32c6-ftdi.cfg
Once OpenOCD is running, you can use GDB to connect to it and debug your application:
riscv-none-elf-gdb -x gdbinit nuttx
whereas the content of the gdbinit
file is:
target remote :3333
set remote hardware-watchpoint-limit 2
mon reset halt
flushregs
monitor reset halt
thb nsh_main
c
Note
nuttx
is the ELF file generated by the build process. Please note that CONFIG_DEBUG_SYMBOLS
must be enabled in the menuconfig
.
Please refer to Debugging for more information about debugging techniques.
Stack Dump and Backtrace Dump
NuttX has a feature to dump the stack of a task and to dump the backtrace of it (and of all the other tasks). This feature is useful to debug the system when it is not behaving as expected, especially when it is crashing.
In order to enable this feature, the following options must be enabled in the NuttX configuration:
CONFIG_SCHED_BACKTRACE
, CONFIG_DEBUG_SYMBOLS
and, optionally, CONFIG_ALLSYMS
.
Note
The first two options enable the backtrace dump. The third option enables the backtrace dump with the associated symbols, but increases the size of the generated NuttX binary.
Espressif also provides a tool to translate the backtrace dump into a human-readable format.
This tool is called btdecode.sh
and is available at tools/espressif/btdecode.sh
of NuttX
repository.
Note
This tool is not necessary if CONFIG_ALLSYMS
is enabled. In this case, the backtrace dump
contains the function names.
Example - Crash Dump
A typical crash dump, caused by an illegal load with CONFIG_SCHED_BACKTRACE
and
CONFIG_DEBUG_SYMBOLS
enabled, is shown below:
riscv_exception: EXCEPTION: Store/AMO access fault. MCAUSE: 00000007, EPC: 420168ac, MT0
riscv_exception: PANIC!!! Exception = 00000007
_assert: Current Version: NuttX 10.4.0 2ae3246e40-dirty Sep 19 2024 14:47:41 risc-v
_assert: Assertion failed panic: at file: :0 task: backtrace process: backtrace 0x42016866
up_dump_register: EPC: 420168ac
up_dump_register: A0: 0000005a A1: 40809fc4 A2: 00000001 A3: 00000088
up_dump_register: A4: 00007fff A5: 00000001 A6: 00000000 A7: 00000000
up_dump_register: T0: 00000000 T1: 00000000 T2: ffffffff T3: 00000000
up_dump_register: T4: 00000000 T5: 00000000 T6: 00000000
up_dump_register: S0: 4080908e S1: 40809078 S2: 00000000 S3: 00000000
up_dump_register: S4: 00000000 S5: 00000000 S6: 00000000 S7: 00000000
up_dump_register: S8: 00000000 S9: 00000000 S10: 00000000 S11: 00000000
up_dump_register: SP: 4080a020 FP: 4080908e TP: 00000000 RA: 420168ac
dump_stack: User Stack:
dump_stack: base: 0x40809098
dump_stack: size: 00004040
dump_stack: sp: 0x4080a020
stack_dump: 0x4080a000: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00001880
stack_dump: 0x4080a020: 00000000 40808c90 42016866 42006e06 00000000 00000000 40809078 00000002
stack_dump: 0x4080a040: 00000000 00000000 00000000 42004d72 00000000 00000000 00000000 00000000
stack_dump: 0x4080a060: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
sched_dumpstack: backtrace| 2: 0x420168ac
dump_tasks: PID GROUP PRI POLICY TYPE NPX STATE EVENT SIGMASK STACKBASE STACKSIZE COMMAND
dump_tasks: ---- --- --- -------- ------- --- ------- ---------- ---------------- 0x40805a90 2048 irq
dump_task: 0 0 0 FIFO Kthread - Ready 0000000000000000 0x40807290 2032 Idle_Task
dump_task: 1 1 100 RR Task - Waiting Semaphore 0000000000000000 0x408081a8 1992 nsh_main
dump_task: 2 2 255 RR Task - Running 0000000000000000 0x40809098 4040 backtrace task
sched_dumpstack: backtrace| 0: 0x42008420
sched_dumpstack: backtrace| 1: 0x420089a2
sched_dumpstack: backtrace| 2: 0x420168ac
The lines starting with sched_dumpstack
show the backtrace of the tasks. By checking it, it is
possible to track the root cause of the crash. Saving this output to a file and using the btdecode.sh
:
./tools/btdecode.sh esp32c6 /tmp/backtrace.txt
Backtrace for task 2:
0x420168ac: assert_on_task at backtrace_main.c:158
(inlined by) backtrace_main at backtrace_main.c:194
Backtrace dump for all tasks:
Backtrace for task 2:
0x420168ac: assert_on_task at backtrace_main.c:158
(inlined by) backtrace_main at backtrace_main.c:194
Backtrace for task 1:
0x420089a2: sys_call2 at syscall.h:227
(inlined by) up_switch_context at riscv_switchcontext.c:95
Backtrace for task 0:
0x42008420: up_idle at esp_idle.c:74
Peripheral Support
The following list indicates the state of peripherals’ support in NuttX:
Peripheral |
Support |
NOTES |
---|---|---|
ADC |
Yes |
Oneshot and internal temperature sensor |
AES |
No |
|
Bluetooth |
No |
|
CAN/TWAI |
Yes |
|
DMA |
Yes |
|
ECC |
No |
|
eFuse |
Yes |
|
GPIO |
Yes |
Dedicated GPIO supported |
HMAC |
No |
|
I2C |
Yes |
Master and Slave mode also LPI2C supported |
I2S |
Yes |
|
LED/PWM |
Yes |
|
MCPWM |
Yes |
|
Pulse Counter |
Yes |
|
RMT |
Yes |
|
RNG |
Yes |
|
RSA |
No |
|
RTC |
Yes |
|
SDIO |
No |
|
SHA |
Yes |
|
SPI |
Yes |
|
SPIFLASH |
Yes |
|
SPIRAM |
No |
|
Temp. Sensor |
No |
|
Timers |
Yes |
|
UART |
Yes |
LPUART supported |
USB Serial |
Yes |
|
Watchdog |
Yes |
|
Wi-Fi |
Yes |
|
XTS |
No |
Analog-to-digital converter (ADC)
One ADC unit is available for the ESP32-C6, with 7 channels.
During bringup, GPIOs for selected channels are configured automatically to be used as ADC inputs. If available, ADC calibration is automatically applied (see this page for more details). Otherwise, a simple conversion is applied based on the attenuation and resolution.
The ADC unit is accessible using the ADC character driver, which returns data for the enabled channels.
The ADC unit can be enabled in the menu
.Then, it can be customized in the menu
, which includes operating mode, gain and channels.Channel |
ADC1 GPIO |
---|---|
0 |
0 |
1 |
1 |
2 |
2 |
3 |
3 |
4 |
4 |
5 |
5 |
6 |
6 |
MCUBoot and OTA Update
The ESP32-C6 supports over-the-air (OTA) updates using MCUBoot.
Read more about the MCUBoot for Espressif devices here.
Executing OTA Update
This section describes how to execute OTA update using MCUBoot.
First build the default
mcuboot_update_agent
config. This image defaults to the primary slot and already comes with Wi-Fi settings enabled:./tools/configure.sh esp32c6-devkitc:mcuboot_update_agent
Build the MCUBoot bootloader:
make bootloader
Finally, build the application image:
make
Flash the image to the board and verify it boots ok. It should show the message “This is MCUBoot Update Agent image” before NuttShell is ready.
At this point, the board should be able to connect to Wi-Fi so we can download a new binary from our network:
NuttShell (NSH) NuttX-12.4.0
This is MCUBoot Update Agent image
nsh>
nsh> wapi psk wlan0 <wifi_ssid> 3
nsh> wapi essid wlan0 <wifi_password> 1
nsh> renew wlan0
Now, keep the board as is and execute the following commands to change the MCUBoot target slot to the 2nd slot and modify the message of the day (MOTD) as a mean to verify the new image is being used.
Change the MCUBoot target slot to the 2nd slot:
kconfig-tweak -d CONFIG_ESPRESSIF_ESPTOOL_TARGET_PRIMARY kconfig-tweak -e CONFIG_ESPRESSIF_ESPTOOL_TARGET_SECONDARY kconfig-tweak --set-str CONFIG_NSH_MOTD_STRING "This is MCUBoot UPDATED image!" make olddefconfig
Note
The same changes can be accomplished through
menuconfig
in for MCUBoot target slot and in for the MOTD.
Rebuild the application image:
make
At this point the board is already connected to Wi-Fi and has the primary image flashed. The new image configured for the 2nd slot is ready to be downloaded.
To execute OTA, create a simple HTTP server on the NuttX directory so we can access the binary remotely:
cd nuttxspace/nuttx
python3 -m http.server
Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) ...
On the board, execute the update agent, setting the IP address to the one on the host machine. Wait until image is transferred and the board should reboot automatically:
nsh> mcuboot_agent http://10.42.0.1:8000/nuttx.bin
MCUboot Update Agent example
Downloading from http://10.42.0.1:8000/nuttx.bin
Firmware Update size: 1048576 bytes
Received: 512 of 1048576 bytes [0%]
Received: 1024 of 1048576 bytes [0%]
Received: 1536 of 1048576 bytes [0%]
[.....]
Received: 1048576 of 1048576 bytes [100%]
Application Image successfully downloaded!
Requested update for next boot. Restarting...
NuttShell should now show the new MOTD, meaning the new image is being used:
NuttShell (NSH) NuttX-12.4.0
This is MCUBoot UPDATED image!
nsh>
Finally, the image is loaded but not confirmed.
To make sure it won’t rollback to the previous image, you must confirm with mcuboot_confirm
and reboot the board.
The OTA is now complete.
Flash Allocation for MCUBoot
When MCUBoot is enabled on ESP32-C6, the flash memory is organized as follows based on the default KConfig values:
Flash Layout (MCUBoot Enabled)
Region |
Offset |
Size |
---|---|---|
Bootloader |
0x000000 |
64KB |
E-Fuse Virtual (see Note) |
0x010000 |
64KB |
Primary Application Slot (/dev/ota0) |
0x020000 |
1MB |
Secondary Application Slot (/dev/ota1) |
0x120000 |
1MB |
Scratch Partition (/dev/otascratch) |
0x220000 |
256KB |
Storage MTD (optional) |
0x260000 |
1MB |
Available Flash |
0x360000+ |
Remaining |
Note: The E-Fuse Virtual region is optional and only used when
ESPRESSIF_EFUSE_VIRTUAL_KEEP_IN_FLASH
is enabled. However, this 64KB
location is always allocated in the memory layout to prevent accidental
erasure during board flashing operations, ensuring data preservation if
virtual E-Fuses are later enabled.
Memory Map (Addresses in hex):
0x000000 ┌─────────────────────────────┐
│ │
│ MCUBoot Bootloader │
│ (64KB) │
│ │
0x010000 ├─────────────────────────────┤
│ E-Fuse Virtual │
│ (64KB) │
0x020000 ├─────────────────────────────┤
│ │
│ Primary App Slot │
│ (1MB) │
│ /dev/ota0 │
│ │
0x120000 ├─────────────────────────────┤
│ │
│ Secondary App Slot │
│ (1MB) │
│ /dev/ota1 │
│ │
0x220000 ├─────────────────────────────┤
│ │
│ Scratch Partition │
│ (256KB) │
│ /dev/otascratch │
│ │
0x260000 ├─────────────────────────────┤
│ │
│ Storage MTD (optional) │
│ (1MB) │
│ │
0x360000 ├─────────────────────────────┤
│ │
│ Available Flash │
│ (Remaining) │
│ │
└─────────────────────────────┘
The key KConfig options that control this layout:
ESPRESSIF_OTA_PRIMARY_SLOT_OFFSET
(default: 0x20000)ESPRESSIF_OTA_SECONDARY_SLOT_OFFSET
(default: 0x120000)ESPRESSIF_OTA_SLOT_SIZE
(default: 0x100000)ESPRESSIF_OTA_SCRATCH_OFFSET
(default: 0x220000)ESPRESSIF_OTA_SCRATCH_SIZE
(default: 0x40000)ESPRESSIF_STORAGE_MTD_OFFSET
(default: 0x260000 when MCUBoot enabled)ESPRESSIF_STORAGE_MTD_SIZE
(default: 0x100000)
For MCUBoot operation:
The Primary Slot contains the currently running application
The Secondary Slot receives OTA updates
The Scratch Partition is used by MCUBoot for image swapping during updates
MCUBoot manages image validation, confirmation, and rollback functionality
ULP LP Core Coprocessor
The ULP LP core (Low-power core) is a 32-bit RISC-V coprocessor integrated into the ESP32-C6 SoC. It is designed to run independently of the main high-performance (HP) core and is capable of executing lightweight tasks such as GPIO polling, simple peripheral control and I/O interactions.
This coprocessor benefits to offload simple tasks from HP core (e.g., GPIO polling , I2C operations, basic control logic) and frees the main CPU for higher-level processing
For more information about ULP LP Core Coprocessor check here.
Features of the ULP LP-Core
- Processor Architecture
RV32I RISC-V core with IMAC extensions—Integer (I), Multiplication/Division (M), Atomic (A), and Compressed (C) instructions
Runs at 20 MHz
- Memory
Access to 16 KB of low-power memory (LP-RAM) and LP-domain peripherals any time
Full access to all of the chip’s memory and peripherals when when the HP core is active
- Debugging
Built-in JTAG debug module for external debugging
Supports LP UART for logging from the ULP itself
Includes a panic handler capable of dumping register state via LP UART on exceptions
- Peripheral support
LP domain peripherals (LP GPIO, LP I2C, LP UART and LP Timer)
Full access HP domain peripherals when when the HP core is active
Loading Binary into ULP LP-Core
- There are two ways to load a binary into LP-Core:
Using a prebuilt binary
Using NuttX internal build system to build your own (bare-metal) application
When using a prebuilt binary, the already compiled output for the ULP system whether built from NuttX or the ESP-IDF environment can be leveraged. However, whenever the ULP code needs to be modified, it must be rebuilt separately, and the resulting .bin file has to be integrated into NuttX. This workflow, while compatible, can become tedious.
With NuttX internal build system, the ULP binary code can be built and flashed from a single location. It is more convenient but using build system has some dependencies on example side.
Both methods requires CONFIG_ESPRESSIF_USE_LP_CORE variable to enable ULP core and CONFIG_ESPRESSIF_ULP_PROJECT_PATH variable to set the path to the ULP project or prebuilt binary file relative to NuttX root folder. These variables can be set using make menuconfig or kconfig-tweak commands.
Here is an example for enabling ULP and using a prebuilt binary for ULP core:
make distclean
./tools/configure.sh esp32c6-devkitc:nsh
kconfig-tweak -e CONFIG_ESPRESSIF_USE_LP_CORE
kconfig-tweak --set-str CONFIG_ESPRESSIF_ULP_PROJECT_PATH "Documentation/platforms/risc-v/esp32c6/boards/esp32c6-devkitc/ulp_blink.bin"
make olddefconfig
make -j
Creating an ULP LP-Core Application
To use NuttX’s internal build system to compile the bare-metal LP binary, check the following instructions.
First, create a folder for the ULP source and header files. This folder is just for ULP project and it is an independent project. Therefore, the NuttX example guide should not be followed, and no Makefile or similar build files should be added. Also folder location could be anywhere. To include ULP folder into build system don’t forget to set CONFIG_ESPRESSIF_ULP_PROJECT_PATH variable with path of the ULP project folder relative to NuttX root folder. Instructions for setting up can be found above.
NuttX’s internal functions or POSIX calls are not supported.
Here is an example:
ULP UART Snippet:
#include <stdint.h>
#include "ulp_lp_core_print.h"
#include "ulp_lp_core_utils.h"
#include "ulp_lp_core_uart.h"
#include "ulp_lp_core_gpio.h"
#define nop() __asm__ __volatile__ ("nop")
int main (void)
{
while(1)
{
lp_core_printf("Hello from the LP core!!\r\n");
for (int i = 0; i < 10000; i++)
{
nop();
}
}
return 0;
}
For more information about ULP Core Coprocessor examples check here. After these settings follow the same steps as for any other configuration to build NuttX. Build system checks ULP project path, adds every source and header file into project and builds it.
To sum up, here is an complete example. ulp_example/ulp (../ulp_example/ulp) folder selected as example to create a subfolder for ULP but folder that includes ULP source code can be anywhere:
Tree view:
nuttxspace/
├── nuttx/
└── apps/
└── ulp_example/
└── ulp/
└── ulp_main.c
Contents in ulp_main.c:
#include <stdint.h>
#include <stdbool.h>
#include "ulp_lp_core_gpio.h"
#define GPIO_PIN 0
#define nop() __asm__ __volatile__ ("nop")
bool gpio_level_previous = true;
int main (void)
{
while (1)
{
ulp_lp_core_gpio_set_level(GPIO_PIN, gpio_level_previous);
gpio_level_previous = !gpio_level_previous;
for (int i = 0; i < 10000; i++)
{
nop();
}
}
return 0;
}
Command to build:
make distclean ./tools/configure.sh esp32c6-devkitc:nsh kconfig-tweak -e CONFIG_ESPRESSIF_GPIO_IRQ kconfig-tweak -e CONFIG_DEV_GPIO kconfig-tweak -e CONFIG_ESPRESSIF_USE_LP_CORE kconfig-tweak --set-str CONFIG_ESPRESSIF_ULP_PROJECT_PATH "../ulp_example/ulp" make olddefconfig make -j
Debugging ULP LP-Core
To debug ULP LP-Core please first refer to Debugging section. Debugging ULP core consist same steps with some small differences. First of all, configuration file needs to be changed from board/esp32c6-builtin.cfg or board/esp32c6-ftdi.cfg to board/esp32c6-lpcore-builtin.cfg or board/esp32c6-lpcore-ftdi.cfg depending on preferred debug adapter.
LP core supports limited set of HW exceptions, so, for example, writing at address 0x0 will not cause a panic as it would be for the code running on HP core. This can be overcome to some extent by enabling undefined behavior sanitizer for LP core application, so ubsan can help to catch some errors. But note that it will increase code size significantly and it can happen that application won’t fit into RTC RAM. To enable ubsan for ULP please add CONFIG_ESPRESSIF_ULP_ENABLE_UBSAN in menuconfig.
Managing esptool on virtual environment
This section describes how to install esptool
, imgtool
or any other Python packages in a
proper environment.
Normally, a Linux-based OS would already have Python 3 installed by default. Up to a few years ago,
you could simply call pip install
to install packages globally. However, this is no longer recommended
as it can lead to conflicts between packages and versions. The recommended way to install Python packages
is to use a virtual environment.
A virtual environment is a self-contained directory that contains a Python installation for a particular version of Python, plus a number of additional packages. You can create a virtual environment for each project you are working on, and install the required packages in that environment.
Two alternatives are explained below, you can select any one of those.
Using pipx (recommended)
pipx
is a tool that makes it easy to install Python packages in a virtual environment. To install
pipx
, you can run the following command (using apt as example):
$ apt install pipx
Once you have installed pipx
, you can use it to install Python packages in a virtual environment. For
example, to install the esptool
package, you can run the following command:
$ pipx install esptool
This will create a new virtual environment in the ~/.local/pipx/venvs
directory, which contains the
esptool
package. You can now use the esptool
command as normal, and so will the build system.
Make sure to run pipx ensurepath
to add the ~/.local/bin
directory to your PATH
. This will
allow you to run the esptool
command from any directory.
Using venv (alternative)
To create a virtual environment, you can use the venv
module, which is included in the Python standard
library. To create a virtual environment, you can run the following command:
$ python3 -m venv myenv
This will create a new directory called myenv
in the current directory, which contains a Python
installation and a copy of the Python standard library. To activate the virtual environment, you can run
the following command:
$ source myenv/bin/activate
This will change your shell prompt to indicate that you are now working in the virtual environment. You can
now install packages using pip
. For example, to install the esptool
package, you can run the following
command:
$ pip install esptool
This will install the esptool
package in the virtual environment. You can now use the esptool
command as
normal. When you are finished working in the virtual environment, you can deactivate it by running the following
command:
$ deactivate
This will return your shell prompt to its normal state. You can reactivate the virtual environment at any time by
running the source myenv/bin/activate
command again. You can also delete the virtual environment by deleting
the directory that contains it.