[#2] ESP32 on Zephyr OS: "Hello, world!" (Blinking LED) [Part 2]

The ESP32 family of microcontrollers are capable devices with many built-in peripherals, including Bluetooth and Wi-Fi. The official SDK and toolchain is the ESP IoT Development Framework (ESP-IDF) and uses FreeRTOS as its real-time operating system.
However, in this tutorial series, we'll use the Zephyr real-time operating system and SDK to program the firmware for the ESP32. This is the second video in the series, so I recommend watching the previous video first: • [#1] ESP32 on Zephyr O...
Links:
Zephyr Getting Started Guide: docs.zephyrproject.org/latest...
ESP32 specific instructions: docs.zephyrproject.org/latest...
ESP32 Technical Reference Manual: www.espressif.com/sites/defau...
Zephyr Devicetree Mysteries, Solved: • Zephyr Devicetree Myst...
Github repository: github.com/bokfink/esp32_zeph...

[@TheIndianSniper]

please make more, Really loved the content, the quality and the information in the video!!!

[@thepullupresistor]

Thank you very much for your encouragement. I've just uploaded the next video in the series, I hope you'll enjoy it, too.

[@vanhuynguyen3892]

this series is super intuitive, and helpful for someone didn't have experience in linux. Thank you so much! Can't believe you only have some hundreds of subs.

[@thepullupresistor]

Your feedback is so valuable to me, as this was the reason I decided to start making these videos in the first place. With regards to subscribers, your individual comments and feedback are far more motivating than having many more subscribers. Knowing that a few people are finding the videos helpful makes my day :-)

[@deterdamel7380]

Again, great content!

[@thepullupresistor]

Thanks again! :-)

[@NewCenturyOfGaming]

Thank you so much for your explanations! I've never worked with Zephyr RTOS before, so your insight has been invaluable to me. Before watching this series, I actually didn't know what .dts and .dtsi files meant or what they were used for. I really appreciate the effort you put into these videos, I learned a lot!

[@thepullupresistor]

Great to know that you found the video series useful. I also didn't know anything about .dts and .dtsi files before exploring Zephyr, and it was quite a steep learning curve.

[@mridulsanthosh811]

Keep on going... We need everything that Zephyr and esp32 can do... Please upload videos regularly... Don't bother about views..

[@thepullupresistor]

Thanks for the encouragement, it really helps to know that you find the content useful.

[@andreyparovozz]

magnificent miracle

[@DerrickEdwards1007]

Great Videos. Thanks

[@thepullupresistor]

Thank you very much for your kind feedback! :-)

[@koxu25cm]

For people wondering why overlay is not included into the final dts file, you need to include this .overlay in CMakeLists with for example "set(DTC_OVERLAY_FILE "esp32.overlay")"

[@thepullupresistor]

Thank you for sharing that insight with everyone! I believe that Zephyr changed the board naming last year, so that the esp32.overlay file was not automatically picked up. Currently, I usually just call my overlay file app.overlay instead of esp32.overlay, as per the manual here: docs.zephyrproject.org/latest/build/dts/howtos.html#set-devicetree-overlays
Thanks again for taking the time to help anyone facing similar issues.

[@jayakrishnanharikumaran676]

Currently we only have pin 25 specified in the blinking_leds port. What if we had more than one pin in the port? would all gpios defined in that port toggle?

[@duyphuong9217]

i love this awesome video, its clearly , Can you make tutorial for nrf5xx with zephyr?. Many thanks

[@thepullupresistor]

It makes me very happy that you found the video useful, thank you for letting me know! I don't have any plans for making tutorials for nrf5xx at the moment, but I'll be sure to keep it in mind for the future :-)

[@SaieenTwist]

Hello, Do you know where to place the overlay file if I am using PlatformIO in Windows?

[@thepullupresistor]

Sorry, but I don't use PlatformIO or Windows so I don't know. Good luck in finding an answer to your problem.

[@fouadayoubi3727]

Thank you for your informative videos. Why is this information given twice: "gpios = " in the overlay file and "ret = gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE)" in main.c? Isn't it redundant?

[@thepullupresistor]

Thank you for the feedback and the excellent question. Whilst GPIO_ACTIVE_HIGH and GPIO_OUTPUT_ACTIVE look quite similar, their meaning is slightly different. In the devicetree overlay file, GPIO_ACTIVE_HIGH says that this pin will have the logical value of 1 (ACTIVE) when the voltage level is HIGH. So, for example, if the voltage on that pin is 3.3V or 5V (depending on your power supply), Zephyr will treat it as a logical value 1 (ACTIVE). If the voltage is at 0V (ground), Zephyr will treat the logical value as 0. If, instead, we had configured the devicetree overlay file to say GPIO_ACTIVE_LOW, then Zephyr would treat 3.3V/5V as a logical 0, and 0V as logical 1 (ACTIVE).
Now, as for the GPIO_OUTPUT_ACTIVE flag, this tells the MCU to treat the GPIO pin pointed to by &gpio0 25 as an output AND set it to logical value 1 (ACTIVE). Since we have configured GPIO_ACTIVE_HIGH in our devicetree, this means that the voltage will be set to 3.3V/5V. If, instead, we had configured the devicetree with GPIO_ACTIVE_LOW, then the MCU would set the voltage to 0V, because this is then the logical value 1 (ACTIVE).
Sorry for the long-winded explanation, but hopefully it makes sense. Please let me know if you're OK or if I misunderstood your question. Thanks again!

[@fouadayoubi3727]

crystal clear, thank you@@thepullupresistor

[@usmanalibutt7832]

&gpio0 > Definition present in .dtsi files

[@thepullupresistor]

Yes, that is a very good point, thank you for highlighting it. I should have mentioned that in the video.