{"id":71,"date":"2026-02-26T11:04:15","date_gmt":"2026-02-26T10:04:15","guid":{"rendered":"https:\/\/elrebo.de\/?p=71"},"modified":"2026-02-26T12:44:04","modified_gmt":"2026-02-26T11:44:04","slug":"i2c_master","status":"publish","type":"post","link":"https:\/\/www.elrebo.de\/index.php\/2026\/02\/26\/i2c_master\/","title":{"rendered":"i2c_master"},"content":{"rendered":"\n

An ESP-IDF component for Physical Computing<\/a><\/p>\n\n\n\n

Purpose<\/h2>\n\n\n\n

Define an I2C bus master and add I2C devices for ESP32 systems.<\/p>\n\n\n\n

How it is done<\/h2>\n\n\n\n

You need to include i2c_master.hpp<\/code>.<\/p>\n\n\n\n

Then you define the I2C bus master by defining an instance of class I2cMaster<\/code>.<\/p>\n\n\n\n

For every I2C device you define an instance of class I2cDevice<\/code> and add it to I2cMaster<\/code> with method AddDevice<\/code>.<\/p>\n\n\n\n

Now the device handles are available through method GetDeviceHandle(std::string deviceName)<\/code> of class I2cMaster<\/code>.<\/p>\n\n\n\n

To transmit data to an I2C device and to receive data from an I2C device you use the original ESP functions. <\/p>\n\n\n\n

Where to find it<\/h2>\n\n\n\n

i2c_master<\/code> is published on the ESP Registry at https:\/\/components.espressif.com\/components\/elrebo-de\/i2c_master<\/a>.<\/p>\n\n\n\n

The source code can be found at\u00a0https:\/\/github.com\/elrebo-de\/i2c_master<\/a>.<\/p>\n\n\n\n

How to use it<\/h2>\n\n\n\n

As an ESP-IDF component i2c_master<\/code> must be included into idf_component.yml as a dependency. As usual this can be done by executing this command:<\/p>\n\n\n\n

idf.py add-dependency \"elrebo-de\/i2c_master^1.1.1\"<\/code><\/p>\n\n\n\n

In CMakeLists.txt \"elrebo-de__i2c_master\"<\/code> has to be added as a requirement.<\/p>\n\n\n\n

Now you can include i2c_master.hpp<\/code> and use the I2cMaster and I2cDevice classes in your program.<\/p>\n\n\n\n

In this code snippet an I2C bus master is defined for an ESP32C3 and two devices are added to the bus, an MCP9808 thermometer device and an LCD display:<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

In this code snippet you see, how the temperature can be read from a MCP9808 temperature sensor using the original ESP I2C transmit and receive functions:<\/p>\n\n\n\n

\"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

An ESP-IDF component for Physical Computing Purpose Define an I2C bus master and add I2C devices for ESP32 systems. How it is done You need to include i2c_master.hpp. Then you define the I2C bus master by defining an instance of class I2cMaster. For every I2C device you define an instance of class I2cDevice and add it to […]<\/p>\n","protected":false},"author":2,"featured_media":121,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-71","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oss"],"_links":{"self":[{"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/posts\/71","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/comments?post=71"}],"version-history":[{"count":3,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/posts\/71\/revisions"}],"predecessor-version":[{"id":130,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/posts\/71\/revisions\/130"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/media\/121"}],"wp:attachment":[{"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/media?parent=71"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/categories?post=71"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.elrebo.de\/index.php\/wp-json\/wp\/v2\/tags?post=71"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}