# Espressif IoT Development Framework

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ESP-IDF is the official development framework for the [ESP32](https://espressif.com/en/products/hardware/esp32/overview) chip.

# Developing With the ESP-IDF

## Setting Up ESP-IDF

See setup guides for detailed instructions to set up the ESP-IDF:

* [Windows Setup Guide](http://esp-idf.readthedocs.io/en/latest/windows-setup.html)
* [Mac OS Setup Guide](http://esp-idf.readthedocs.io/en/latest/macos-setup.html)
* [Linux Setup Guide](http://esp-idf.readthedocs.io/en/latest/linux-setup.html)

## Finding a Project

As well as the [esp-idf-template](https://github.com/espressif/esp-idf-template) project mentioned in the setup guide, ESP-IDF comes with some example projects in the [examples](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 `Y` and `N` keys 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](http://esp-idf.readthedocs.io/en/latest/idf-monitor.html) 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](http://esp-idf.readthedocs.io/en/latest/idf-monitor.html).

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

* Documentation for the latest version: http://esp-idf.readthedocs.io/. This documentation is built from the [docs directory](docs) of this repository.

* The [esp32.com forum](http://esp32.com/) is a place to ask questions and find community resources.

* [Check the Issues section on github](https://github.com/espressif/esp-idf/issues) if you find a bug or have a feature request. Please check existing Issues before opening a new one.

* If you're interested in contributing to ESP-IDF, please check the [Contributions Guide](http://esp-idf.readthedocs.io/en/latest/contributing.html>).

