Ioto on ESP32

The Espressif ESP32 is a low-cost, low-power system-on-chip (SoC) developed by Espressif Systems. It is widely used in embedded systems and IoT devices due to its versatility, strong performance, and integrated features.

Ioto brings to the ESP32 a new standard of IoT device management with: transparent database synchronization to the cloud, a no-code app designer for mobile and desktop interfaces and unlimited metrics for extensive device metrics. Ioto is the most intelligent IoT middleware for AWS.

This post details the steps required to build Ioto for ESP32 boards using the ESP IDF.

Please read the Building Ioto for general background first and Supported Hardware for a list of supported hardware.

Building Requirements

The Espressif ESP32 comes in many different varieties and flavors. Ioto will run on most ESP32 chips and has the following requirements:

• 256 KB internal RAM
• 2MB PSIRAM

Here’s a table summarizing the most common ESP32 chip variants, including the amount of RAM, number of cores, and supported PSRAM (external RAM):

Building Ioto for ESP32

This build sequence assumes you have your development environment setup on Linux or MacOS with the ESP-IDF installed. See ESP-IDF Setup for details.

To begin, open a terminal and create a directory for your project and the Ioto component. Choose any name you like for the project directory.

mkdir -p myproject
cd myproject
mkdir components

Next, add the ESP IDF PATH to your environment.

. ~/path-to-esp-idf/export.sh

Download Ioto

To download the Ioto device agent, navigate to the Builder site and select Products in the sidebar menu and click on the download link for the Ioto Evaluation.

Extract the Ioto source code into the components directory. Then rename the ioto-VERSION directory to ioto.

cd components
tar xvfz ioto-VERSION.tgz
mv ioto-* ioto
cd ..

Sample apps

The Ioto source distribution includes several ESP32 example apps. Each example includes the necessary configuration files that are copied from the relevant app directory into build tree.

The default app is the esp32-blink app which is ideal to test wheter you have ESP and Ioto successfully installed and configured. You can select an app by providing an APP=NAME option to the make command.

To prepare for building the app and Ioto, invoke make with your selected app.

make -C components/ioto esp32

or

make -C components/ioto APP=esp32-blink esp32

This command will perform the following steps:

• Create the esp32-blink app at main/main.c
• Create the app CMakeLists.txt
• Create the file system partitions.csv
• Create the app sdkconfig.defaults
• Initialize the components/ioto for the blink app
• Create some test certificates that may be required by the app

The components/ioto/apps directory contains master copies of the Ioto demonstration apps. When you select an app, the app code and configuration are copied to the ./main and ./fs directories.

Board Configuration

The next step is to ensure your ESP target device is defined. For example, to set the target to esp32-s3, invoke:

idf.py set-target esp32-s3

The default build configuration is defined via the sdkconfig.defaults file. You can tailor the configuration by running:

idf.py menuconfig

The Ioto services are enabled via the Ioto menu config option. Navigate to:

Components config ---> 
Ioto

then enable the desired services. This will update the fs/config/ioto.json5 and regenerate the sdkconfig and include/ioto-config.h files.

Check your sdkconfig that the following settings are defined:

The full list is in components/ioto/apps/NAME/sdkconfig.defaults.

Building with idf.py

Building is performed via the ESP-IDF idf.py command instead of using the normal Ioto Makefiles which are used when building natively on Linux or MacOS.

To build for ESP32, run:

idf.py build

Update the Board Flash

To update your device with the built application:

idf.py -p PORT flash

Where PORT is set to the USB/TTY serial port connected to your device.

Monitoring Output

You can view the ESP32 and Ioto trace via the ESP32 monitor:

idf.py monitor

When running, the esp32-blink app will turn the LED On/Off every 2 seconds and trace the LED status to the monitor.

Local Management

If the selected app enables the embedded web server, files will be served from the ./site directory. The Ioto embedded web server is configured via the config/web.json5 configuration file which is then copied to the fs/config/web.json5 directory.

Tech Notes

The stack size is configured to be 32K for the main app task and for spawned fiber tasks. Observationally, the minimum stack for the core Ioto is ~14K.

Ioto uses its own optimized printf implementation which uses less stack (<1K) and is more secure, being tolerant of errant NULL arguments.

The PlatformIO and Arduino build frameworks are not (yet) supported.