Alan C Assis Blog on EmbeddedRelated.com https://www.embeddedrelated.com/blogs-1/nf/Alan_C_Assis.php Alan C Assis Blog on EmbeddedRelated.com https://www.embeddedrelated.com/blogs-1/nf/Alan_C_Assis.php https://d23s79tivgl8me.cloudfront.net/user/profilepictures/80764.jpg en-US Fri, 16 Oct 2026 14:21:11 +0000 1792160471 Using a board with NuttX RTOS as an RS-485 / Modbus Slave Device https://www.embeddedrelated.com/showarticle/1715.php Until now we saw how to connect local sensors, actuators and also some kinds of analog devices in our board, but for Industrial application it is very common to use remote devices over some bus, and RS-485 and Modbus (a protocol over physical layer of RS-485) is very common and low cost bus for this kind of application.

And a good thing about RS-485 on NuttX is because you just need an...]]> Sun, 22 Dec 2024 18:44:40 +0000 Alan C Assis How to use analog input (ADC) on NuttX RTOS https://www.embeddedrelated.com/showarticle/1689.php In all previous tutorial about NuttX we used some type of digital interface (I2C, SPI, etc), so today we will see how to use an analog interface to read some analog sensor or other analog device. In fact we live in an analog world and sometimes we need to read some analog voltage to make sense of some external analog signal. Today we will see how to use the ADC (Analog Digital Converter) from...]]> Sat, 21 Sep 2024 19:58:31 +0000 Alan C Assis How to use SPI devices in NuttX RTOS https://www.embeddedrelated.com/showarticle/1673.php Previously in this EmbeddedRelated article, we saw how to use I2C device connected to your board. Although I2C devices are very common nowadays, probably you will need to use some SPI device as well. Today we will see how to do exactly that. So, lets to get started!

 

The SPI (Serial Peripheral Interface) is synchronous serial communication protocol (by...]]> Sun, 30 Jun 2024 23:00:18 +0000 Alan C Assis How to use I2C devices in (Apache) NuttX: Adding support for an I2C device in your board https://www.embeddedrelated.com/showarticle/1668.php Previously in this EmbeddedRelated article, we saw how to find an I2C device connected to your board using the i2ctool that is very familiar for people with previous experience with embedded Linux. Today we will see how to add support to an I2C device (i.e. BMP280 sensor) in your board. So, lets to get started!

NuttX uses a...]]> Tue, 28 May 2024 22:30:04 +0000 Alan C Assis How to use I2C devices in (Apache) NuttX: Scanning for Devices https://www.embeddedrelated.com/showarticle/1656.php Previously in this EmbeddedRelated article, we saw how to use Buttons Subsystem on NuttX using a RaspberryPi Pico board. Now we will change from user input device (buttons) for something more generic: I2C protocol. NuttX supports a lot of I2C devices (sensors, displays, EEPROMs, I/O Expanders, I2C multiplexers, and many more). And most important: because NuttX is a Linux-like RTOS you...]]> Mon, 22 Apr 2024 19:01:53 +0000 Alan C Assis Using (Apache) NuttX Buttons Subsystem https://www.embeddedrelated.com/showarticle/1646.php Previously in this EmbeddedRelated article, we saw how to use LEDs Subsystem on NuttX testing on RaspberryPi Pico. In the same way we avoided using GPIO Subsystem to control LEDs we can avoid using GPIO Subsystem to read Buttons inputs. That is right, NuttX has an Input Device Subsystem like Linux and today we will learn how to use it.

https://embeddedrelated.com/showarticle/1623.php) we saw how to use GPIOs on NuttX testing on RaspberryPi Pico as example. In that article we used the GPIO output to control an LED, but there is a better way to do that. Of course, NuttX has an LED subsystem similar to Linux LED subsystem: it is called USERLED. Today we will see how to control LEDs using NuttX's USERLED...]]> Mon, 19 Feb 2024 14:26:29 +0000 Alan C Assis Using GPIO in (Apache) NuttX RTOS https://www.embeddedrelated.com/showarticle/1623.php In the previous article (https://embeddedrelated.com/showarticle/1610.php) we saw how to compile and run NuttX on three low cost boards (RaspberryPi Pico, ESP32-Devkit and STM32F4Discovery). Today we will see how to use GPIO pins and read and write logic level signals from/to the MCU pins.

Everybody knows that blinking a LED is the "Hello World" program of...]]> Sun, 21 Jan 2024 16:34:09 +0000 Alan C Assis Getting Started with NuttX RTOS on Three Low Cost Boards https://www.embeddedrelated.com/showarticle/1610.php If you are an embedded system developer chances are you already played with Linux on some embedded board and saw how it is powerful, right?

So, I have a good news: you can have same power using NuttX on some ultra low cost board powered by a microcontroller instead of microprocessor (that normally is way more expansive).

In fact many companies already realized it before me. It explains...]]> Mon, 27 Nov 2023 21:39:13 +0000 Alan C Assis Getting Started with (Apache) NuttX RTOS Part 2 - Looking Inside and Creating Your Customized Image https://www.embeddedrelated.com/showarticle/1543.php In the previous article (https://www.embeddedrelated.com/showarticle/1524.p...) we saw how to run NuttX RTOS using the SIMulator. Today we will see how NuttX's directory tree is organized and how to use the menuconfig to enable some applications, including some tricks to search and solve dependencies.

NuttX Directories organization:

If...]]> Wed, 05 Jul 2023 20:59:29 +0000 Alan C Assis Getting Started with (Apache) NuttX RTOS - Part 1 https://www.embeddedrelated.com/showarticle/1524.php Probably you have already heard about Apache NuttX RTOS, a small RTOS but very powerful in resources and features, but never stopped to look deeper into it. So let us start by raising a question: What separates NuttX from other RTOSes like FreeRTOS, Mbed, VxWorks, uC/OS-II, Contiki, Zephyr, RT-Thread, ThreadX, RIOT-OS, ChibiOS/RT and many others?

Well, first of all,...]]> Fri, 02 Jun 2023 21:05:02 +0000 Alan C Assis