94b91ee4af
This issue is reported from https://github.com/espressif/esp-idf/issues/304. We found that when we operate the hw command registers in I2C struct, sometimes the behaviour would be different in DEBUG/RELEASE optimisation level: The code looks like this: I2C[i2c_num]->command[p_i2c->cmd_idx].byte_num -= 0; In DEBUG configuration: I2C[i2c_num]->command[p_i2c->cmd_idx].byte_num -= 0; 400f3ab0: 3388 l32i.n a8, a3, 12 400f3ab2: 14c882 addi a8, a8, 20 400f3ab5: a08840 addx4 a8, a8, a4 400f3ab8: 0020c0 memw 400f3abb: 2898 l32i.n a9, a8, 8 400f3abd: 0020c0 memw 400f3ac0: 28b8 l32i.n a11, a8, 8 400f3ac2: 74a090 extui a10, a9, 0, 8 400f3ac5: 00af92 movi a9, 0xffffff00 400f3ac8: 109b90 and a9, a11, a9 400f3acb: 2099a0 or a9, a9, a10 400f3ace: 0020c0 memw 400f3ad1: 2899 s32i.n a9, a8, 8 In RELEASE configuration: I2C[i2c_num]->command[p_i2c->cmd_idx].byte_num -= 0; 400f2ba2: 580572 l8ui a7, a5, 88 400f2ba5: 747070 extui a7, a7, 0, 8 400f2ba8: 0020c0 memw 400f2bab: 584572 s8i a7, a5, 88 Looks like the compiler will make it a 8bit operation after optimisation. But the register value changes from 0x901 to 0x101. After this 8-bit optimisation, the 11th bit changed from 1 to zero, which caused this error. We are still trying to find out why that happens, because there might be some risk when operating the register struct. This is a workaround to avoid "-=" operation on I2C register struct fields.
Espressif IoT Development Framework
ESP-IDF is the official development framework for the ESP32 chip.
Developing With the ESP-IDF
Setting Up ESP-IDF
See setup guides for detailed instructions to set up the ESP-IDF:
Finding a Project
As well as the esp-idf-template project mentioned in the setup guide, ESP-IDF comes with some example projects in the examples directory.
Once you've found the project you want to work with, change to its directory and you can configure and build it.
Configuring the Project
make menuconfig
- Opens a text-based configuration menu for the project.
- Use up & down arrow keys to navigate the menu.
- Use Enter key to go into a submenu, Escape key to go out or to exit.
- Type
?to see a help screen. Enter key exits the help screen. - Use Space key, or
YandNkeys to enable (Yes) and disable (No) configuration items with checkboxes "[*]" - Pressing
?while highlighting a configuration item displays help about that item. - Type
/to search the configuration items.
Once done configuring, press Escape multiple times to exit and say "Yes" to save the new configuration when prompted.
Compiling the Project
make all
... will compile app, bootloader and generate a partition table based on the config.
Flashing the Project
When make all finishes, it will print a command line to use esptool.py to flash the chip. However you can also do this from make by running:
make flash
This will flash the entire project (app, bootloader and partition table) to a new chip. The settings for serial port flashing can be configured with make menuconfig.
You don't need to run make all before running make flash, make flash will automatically rebuild anything which needs it.
Viewing Serial Output
The make monitor target uses the idf_monitor tool to display serial output from the ESP32. idf_monitor also has a range of features to decode crash output and interact with the device. Check the documentation page for details.
Exit the monitor by typing Ctrl-].
To flash and monitor output in one pass, you can run:
make flash monitor
Compiling & Flashing Just the App
After the initial flash, you may just want to build and flash just your app, not the bootloader and partition table:
make app- build just the app.make app-flash- flash just the app.
make app-flash will automatically rebuild the app if it needs it.
(In normal development there's no downside to reflashing the bootloader and partition table each time, if they haven't changed.)
Parallel Builds
ESP-IDF supports compiling multiple files in parallel, so all of the above commands can be run as make -jN where N is the number of parallel make processes to run (generally N should be equal to or one more than the number of CPU cores in your system.)
Multiple make functions can be combined into one. For example: to build the app & bootloader using 5 jobs in parallel, then flash everything, and then display serial output from the ESP32 run:
make -j5 flash monitor
The Partition Table
Once you've compiled your project, the "build" directory will contain a binary file with a name like "my_app.bin". This is an ESP32 image binary that can be loaded by the bootloader.
A single ESP32's flash can contain multiple apps, as well as many different kinds of data (calibration data, filesystems, parameter storage, etc). For this reason a partition table is flashed to offset 0x4000 in the flash.
Each entry in the partition table has a name (label), type (app, data, or something else), subtype and the offset in flash where the partition is loaded.
The simplest way to use the partition table is to make menuconfig and choose one of the simple predefined partition tables:
- "Single factory app, no OTA"
- "Factory app, two OTA definitions"
In both cases the factory app is flashed at offset 0x10000. If you make partition_table then it will print a summary of the partition table.
For more details about partition tables and how to create custom variations, view the docs/partition-tables.rst file.
Erasing Flash
The make flash target does not erase the entire flash contents. However it is sometimes useful to set the device back to a totally erased state, particularly when making partition table changes or OTA app updates. To erase the entire flash, run make erase_flash.
This can be combined with other targets, ie make erase_flash flash will erase everything and then re-flash the new app, bootloader and partition table.
Resources
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Documentation for the latest version: http://esp-idf.readthedocs.io/. This documentation is built from the docs directory of this repository.
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The esp32.com forum is a place to ask questions and find community resources.
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Check the Issues section on github if you find a bug or have a feature request. Please check existing Issues before opening a new one.
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If you're interested in contributing to ESP-IDF, please check the Contributions Guide.