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ESP-IDF Library

note-espidf is the official ESP-IDF framework component for communicating with the Notecard over serial or I2C. In this article, you'll learn how to use note-espidf with an ESP32-based development board with Notecard communication! This library is designed to work with the ESP-IDF framework version 5.5 or later (previous versions may work, but are not tested). It supports the following Espressif chips:

  • ESP32
  • ESP32-S2
  • ESP32-C3
  • ESP32-S3
  • ESP32-C2
  • ESP32-C6
  • ESP32-H2
  • ESP32-P4
  • ESP32-C5
  • ESP32-C61

Overview

This example is designed to illustrate the ease of using Notecard functionality with an ESP32-based development board. Functionally, the application reads Notecard's temperature and voltage, using the card.temp and card.voltage requests, and sends a Note to Notehub with the data. This example is considered "advanced" as it uses FreeRTOS and the ESP-IDF framework, which uses specific design considerations (RTOS, Mutexes, etc.).

This example walks through using the ESP-IDF with Visual Studio Code (VSCode) and the ESP-IDF extension . The ESP-IDF extension will download the pre-requisites in order to use the ESP-IDF framework.

Use the Installation Guide from Espressif to get started with the ESP-IDF extension.

Requirements

Hardware

Software

Cloudware

Getting Set Up

Notehub.io

Before you can utilize this example, you must set up a free account (no credit card required) on Notehub.io . Once you have created your account, then you need to create a project to serve as an endpoint for the Notes that are tracking the state of the LED.

Once you have a project, you will need to update the define named PROJECT_UID in main.c with the UID of the project you have just created.

After the Notecard has connected to Notehub, you can look inside the project and see a device named espidf-i2c. The Notecard will be running in continuous mode, which will allow it to maintain a constant cellular connection. continuous mode offers the lowest latency possible for sending messages to Notehub, but it comes at the cost of battery life. Fortunately, this is typically not a concern while bench testing.

To learn more about the Notecard modes and API, please visit our Essential Requests Walkthrough.

Downloading the Example Project

First, select an empty directory to create the example project and open it in VS Code. Now open the Command Palette and select ESP-IDF: Open ESP-IDF Terminal and press enter.

Use the following command to create the example project.

idf.py create-project-from-example "blues/notecard:basic_usage_i2c"

This will create a new directory called basic_usage_i2c, pre-populated with the example code for the Notecard I2C example.

note

If you want to build the UART example instead, use basic_usage_uart instead of basic_usage_i2c.

To point the ESP-IDF extension at the example, you'll need to:

  1. Open Command Palette and select Workspaces: Add Folder to Workspace.
  2. From there, select the basic_usage_i2c folder and press enter.
  3. Then, you'll need to tell the ESP-IDF that this is your target project.
  4. In the Command Palette, select ESP-IDF: Pick Workspace Folder and select basic_usage_i2c from the dropdown.
  5. Now you can use the ESP-IDF extension to build, flash, and monitor the project.

Buttons to build, flash, and monitor the project are located in the bottom left corner of the VS Code window.

ESP-IDF extension buttons

Building and Running

Connect your ESP32 Feather's USB C port to your computer.

Using the following Command Palette option, you can build, flash, and monitor the projectESP-IDF: Build, Flash, and Start a Monitor on Your Device

Or, you can use the following Build, Flash, and Monitor button.

ESP-IDF extension build

note

Check that the correct serial port is selected with the ESP-IDF: Select Port to Use command.

Building

To build the project, you can either use the following Command Palette option, ESP-IDF: Build Your Project,

Or, you can use the following Build button.

ESP-IDF extension build

Flashing

To flash the project, you can either use the following Command Palette option, ESP-IDF: Flash Your Project,

Or, you can use the following Flash button.

ESP-IDF extension flash

Monitoring

To monitor the project, you can either use the following Command Palette option, ESP-IDF: Monitor Device,

Or, you can use the following Monitor button.

ESP-IDF extension monitor

Changing Transport

To change the transport, you can modify the notecard_config_t config = NOTECARD_I2C_CONFIG_DEFAULT(); object in main.c.

If you want to use the Notecard's UART interface, you can modify the config object to use the NOTECARD_UART_CONFIG_DEFAULT() macro.

Additional Configurations

If you wish to adjust the I2C configuration, you need to override the NOTECARD_I2C_CONFIG_DEFAULT() macro.

// Configure Notecard for I2C communication using Kconfig defaults
notecard_config_t config = NOTECARD_I2C_CONFIG_DEFAULT();

// Or override the default options
config.i2c.port = 0;
config.i2c.sda_pin = 22;
config.i2c.scl_pin = 20;
config.i2c.frequency = 100000;
config.i2c.address = 0x17;
config.i2c.internal_pullup = false;

The same can be done for the UART configuration, by overriding the NOTECARD_UART_CONFIG_DEFAULT() macro.

// Configure Notecard for UART communication using Kconfig defaults
notecard_config_t config = NOTECARD_UART_CONFIG_DEFAULT();

// Or override the default options
config.uart.port = 0;
config.uart.tx_pin = 21;
config.uart.rx_pin = 20;
config.uart.rts_pin = 23;
config.uart.cts_pin = 24;
config.uart.baudrate = 9600;
config.uart.tx_buffer_size = 1024;
config.uart.rx_buffer_size = 1024;
note

The default options are also configurable within the Kconfig file. Use the make menuconfig command to view and modify the default options.

Alternatively, you can modify the Kconfig file to change the default options.

idf.py menuconfig

This will open the menuconfig tool, where you can modify the default options.

ESP-IDF menuconfig

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