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98 lines
4.5 KiB
Markdown
98 lines
4.5 KiB
Markdown
2 years ago
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# NuttX RTOS
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## What is NuttX?
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[NuttX](https://nuttx.apache.org/) is a mature and secure real-time operating system (RTOS) with an emphasis on technical standards compliance and small size.
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It is scalable from 8-bit to 64-bit microcontrollers and microprocessors and compliant with the Portable Operating System Interface (POSIX) and the American National Standards Institute (ANSI) standards and with many Linux-like subsystems.
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The best way to think about NuttX is to think of it as a small Unix/Linux for microcontrollers.
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### Highlights of NuttX
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- **Small** - Fits and runs in microcontrollers as small as 32 kB Flash and 8 kB of RAM.
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- **Compliant** - Strives to be as compatible as possible with POSIX and Linux.
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- **Versatile** - Supports many architectures (ARM, ARM Thumb, AVR, MIPS, OpenRISC, RISC-V 32-bit and 64-bit, RX65N, x86-64, Xtensa, Z80/Z180, etc.).
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- **Modular** - Its modular design allows developers to select only what really matters and use modules to include new features.
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- **Popular** - NuttX is used by many companies around the world. Probably you already used a product with NuttX without knowing it was running NuttX.
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- **Predictable** - NuttX is a preemptible Realtime kernel, so you can use it to create predictable applications for realtime control.
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---
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## Why NuttX + LVGL?
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Although NuttX has its own graphic library called [NX](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=139629474), LVGL is a good alternative because users could find more eye-candy demos and they can reuse code from previous projects.
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LVGL is an [Object-Oriented Component Based](https://blog.lvgl.io/2018-12-13/extend-lvgl-objects) high-level GUI library, that could fit very well for a RTOS with advanced features like NuttX.
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LVGL is implemented in C and its APIs are in C.
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### Here are some advantages of using LVGL in NuttX
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- Develop GUI in Linux first and when it is done just compile it for NuttX. Nothing more, no wasting of time.
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- Usually, GUI development for low level RTOS requires multiple iterations to get things right, where each iteration consists of **`Change code` > `Build` > `Flash` > `Run`**.
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Using LVGL, Linux and NuttX you can reduce this process and just test everything on your computer and when it is done, compile it on NuttX and that is it.
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### NuttX + LVGL could be used for
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- GUI demos to demonstrate your board graphics capacities.
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- Fast prototyping GUI for MVP (Minimum Viable Product) presentation.
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- visualize sensor data directly and easily on the board without using a computer.
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- Final products with a GUI without a touchscreen (i.e. 3D Printer Interface using Rotary Encoder to Input data).
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- Final products with a touchscreen (and all sorts of bells and whistles).
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---
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## How to get started with NuttX and LVGL?
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There are many boards in the [NuttX mainline](https://github.com/apache/incubator-nuttx) with support for LVGL.
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Let's use the [STM32F429IDISCOVERY](https://www.st.com/en/evaluation-tools/32f429idiscovery.html) as an example because it is a very popular board.
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### First you need to install the pre-requisites on your system
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Let's use the [Windows Subsystem for Linux](https://acassis.wordpress.com/2018/01/10/how-to-build-nuttx-on-windows-10/)
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```shell
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$ sudo apt-get install automake bison build-essential flex gcc-arm-none-eabi gperf git libncurses5-dev libtool libusb-dev libusb-1.0.0-dev pkg-config kconfig-frontends openocd
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```
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### Now let's create a workspace to save our files
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```shell
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$ mkdir ~/nuttxspace
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$ cd ~/nuttxspace
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```
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### Clone the NuttX and Apps repositories:
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```shell
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$ git clone https://github.com/apache/incubator-nuttx nuttx
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$ git clone https://github.com/apache/incubator-nuttx-apps apps
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```
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### Configure NuttX to use the stm32f429i-disco board and the LVGL Demo
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```shell
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$ ./tools/configure.sh stm32f429i-disco:lvgl
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$ make
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```
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If everything went fine you should have now the file `nuttx.bin` to flash on your board:
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```shell
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$ ls -l nuttx.bin
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-rwxrwxr-x 1 alan alan 287144 Jun 27 09:26 nuttx.bin
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```
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### Flashing the firmware in the board using OpenOCD:
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```shell
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$ sudo openocd -f interface/stlink-v2.cfg -f target/stm32f4x.cfg -c init -c "reset halt" -c "flash write_image erase nuttx.bin 0x08000000"
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```
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Reset the board and using the 'NSH>' terminal start the LVGL demo:
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```shell
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nsh> lvgldemo
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```
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## Where can I find more information?
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- This blog post: [LVGL on LPCXpresso54628](https://acassis.wordpress.com/2018/07/19/running-nuttx-on-lpcxpresso54628-om13098/)
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- NuttX mailing list: [Apache NuttX Mailing List](http://nuttx.incubator.apache.org/community/)
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