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Learning how to program microcontrollers

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Why do you need the MISRA Compliance report and how to generate one in PVS-Studio?

Reading time 5 min
Views 837

If you are strongly interested in MISRA and would like to understand whether your project meets one of the MISRA association's standards, there is a solution. It's name is MISRA Compliance. PVS-Studio has recently learned how to generate the MISRA Compliance report. This article describes how you can use this feature. This can make somebody's life better.

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Rating 0
Comments 3

System-on-Chip bus: AXI4 simplified and explained

Reading time 20 min
Views 26K

Protocol AXI4 was developed for High-bandwidth and low latency applications. It is designed to allow communication between master and slave devices. Master is typically a DMA or CPU and slaves are DRAM controllers, or other specific protocol controllers: UART, SPI, and others. Sometimes one component can implement multiple instances of this protocol. Usually, a prefix is used to differentiate between multiple AXI4 interfaces.

For example, Ethernet MAC can integrate DMA and slave interface used to command MAC. MAC can accept commands on the slave interface that contain data about the location of the next ethernet packet and MAC can start fetching this packet using the separate master interface instance.

This article was motivated by common design mistakes AXI4 designers make when they are designing their Digital IP. (Looking at you Xilinx)

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Total votes 10: ↑10 and ↓0 +10
Comments 1

Doubling effective digitization frequency by multiple pass approach, is it possible?

Reading time 4 min
Views 968

As already described in the previous article, in the process of reworking the DSO138 oscilloscope toy, the idea arose in the DSO303 firmware at some point to try to double the maximum sampling frequency to achieve scanning times of 500 and 200 nanoseconds per cell. In fact, for the STM32F303, the theoretically maximum achievable sampling rate from the point of view of the ADC input, and this is determined by the minimum opening time of the ADC sampling unit, which in our case is 1.5 clock cycles x (1/72 MHz) = 20.8 nanoseconds, is 48 MSPS (millions of counts per second). However, with the parallel operation of 4 ADCs at 6 MHz, it is possible to achieve only 24 MSPS due to the limited speed of the ADC.

Let's imagine that we are considering correctly-periodic signal, which is also constant, i.e. it does not experience fluctuations in frequency and amplitude over time. Is it possible to somehow digitize it not in one, but in several passes, thereby increasing the effective sampling frequency? 

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DSO138 upgrade

Reading time 11 min
Views 4.2K

On Ali, an interesting toy – an oscilloscope called DSO138 is sold for a very inexpensive price. It has already gained quite a lot of popularity among electronics lovers, but the parameters of this device, alas, allow it to be more or less fully used only for debugging very low-frequency circuits. Actually, it is not positioned as a tool, but rather as a DIY-kit for novice electronics engineers.

This "toy" oscilloscope is assembled on the STM32F103 microcontroller, and with a fairly competent circuit design of the digital part, the presence of a fairly decent 320X240-dot color display, and not the most rotten analog path, everything, alas, is ruined by very weak ADCs on board the 32F103. The claimed band of 200 kHz can be recognized as such only with a very large stretch. Yes, it will show the presence or absence of a signal with such a frequency, but it will not be possible to really look at something beyond this.

At the same time, the 103-series has a slightly more powerful brother - the STM32F303, it is almost completely compatible with the legs, but it is significantly better in terms of the parameters we are interested in, there are 4 ADCs on board with a conversion frequency of 5 MHz (6 MHz with a 10-bit resolution). In this scenario, if you use all 4 ADCs in parallel with a 10-bit resolution, you can get a effective resolution of up to an honest 24 MSPS (millions of samples per second). The microcontroller is also inexpensive; you can easily find it on the same Ali for very reasonable money again. It is clear that the idea to change the microcontroller arose almost immediately after I tried this DSO138.

At the same time, if upgraded the toy can turn out to be a completely full-fledged tool that even professionals, not just novice amateurs, could already use. With these thoughts in mind, I decided to try to do something with a Chinese toy in my free time.

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Total votes 5: ↑5 and ↓0 +5
Comments 0

Building an Arduino based RFID Emulator

Reading time 7 min
Views 13K

This project is aimed at creating an experimental device for emulating RFID labels of three widely available components. I simplified the explanation of the process so that it could be easily replicated. I also developed some helpful ideas along the way, including writing a special program for converting a serial number into the transmitted data, which will definitely prove useful.
Total votes 21: ↑20 and ↓1 +19
Comments 0

Passcode Data Protection by Using FPGA and Verilog

Reading time 4 min
Views 2.7K

There are many situations when you need to protect your data, and different tools can be used to do that. For example, a safe. We develop a passcode data protection mechanism by using an FPGA board and Quartus Prime software. It allows demonstrating the basic concepts of a combination lock such as entering data, setting and checking a passcode, and displaying data.

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Total votes 5: ↑3 and ↓2 +1
Comments 0

Configuring FT4232H using the ftdi_eeprom

Reading time 2 min
Views 6K


The FT4232H is USB 2.0 High speed to UART IC converter. The FT4232H has four UART ports and one USB port.


By connecting EEPROM memory to this chip, you can set specific operating modes or change the manufacturer's data.


Let's look at the example and configure FT4232H directly on a system running GNU/Linux. We will do this using the ftdi_eeprom.

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Total votes 2: ↑2 and ↓0 +2
Comments 0

How to make your home ‘smart’ without going crazy

Reading time 10 min
Views 1.9K
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Smart furniture, which keeps your house in order, is a must for almost any futuristic set. In fact, an auto-regulating climate, automatic lights and voice control over household devices — all this can be done and configured now. But it will take a little experience, basic knowledge of technology and sometimes programming, as well as a whole sea of ​​fantasy. In my case, I did in the way that just fantasy will be enough, but first things first…
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Total votes 2: ↑2 and ↓0 +2
Comments 1

About embedded again: searching for bugs in the Embox project

Reading time 11 min
Views 521

Рисунок 2


Embox is a cross-platform, multi-tasking real-time operating system for embedded systems. It is designed to work with limited computing resources and allows you to run Linux-based applications on microcontrollers without using Linux itself. Certainly, the same as other applications, Embox couldn't escape from bugs. This article is devoted to the analysis of errors found in the code of the Embox project.
Total votes 3: ↑3 and ↓0 +3
Comments 0

Checking the Code of Zephyr Operating System

Reading time 13 min
Views 1.9K

PVS-Studio and Zephyr

Some time ago we announced PVS-Studio's new feature that enabled it to integrate into PlatformIO. Naturally, our team kept in touch with the PlatformIO team while working on that feature, and they suggested that we check the real-time operating system Zephyr to see if we could find any interesting bugs in its code. We thought it was a good idea, and so here's this article about the check results.
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Total votes 4: ↑3 and ↓1 +2
Comments 0

What Is MISRA and how to Cook It

Reading time 11 min
Views 1.1K

Рисунок 2

Perhaps every microcontroller software developer has heard about special coding standards to help improve the code security and portability. One of such standards is MISRA. In this article, we'll take a closer look at what this standard is, its concept and how to use it in your projects.
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Total votes 4: ↑2 and ↓2 0
Comments 0

On request of Embedded Developers: Detecting Errors in Amazon FreeRTOS

Reading time 15 min
Views 1.3K
Anyone who programs microcontrollers probably knows about FreeRTOS, or at least heard of this operating system. Amazon developers decided to enhance the abilities of this operating system to work with AWS Internet of Things services. This is how Amazon FreeRTOS appeared. We, developers of the PVS-Studio static code analyzer, were asked by mail and in comments to check these projects. Well, now get what you asked for. Keep reading to find out what came out of it.


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Total votes 27: ↑27 and ↓0 +27
Comments 0

Building a Bare-Metal Application on Intel Cyclone V for Absolute Beginners

Reading time 7 min
Views 8.8K
Setting up Linux on the development board like SocKit with a double-core ARM Cortex A9 is not rocket science. A manufacturer of the board supports the ready-to-use image, appropriate for installing on SD card or another media. But what if you are craving to touch bare metal, approaching a neck-breaking speed of code not restrained by an OS core? Well, it is possible, but not so easy and obvious. In this short essay, I'll give you step-by-step instruction, how to build and run you first bare-metal application on Cyclone V SoC, that uses ARM Cortex A9 core of the HPS subsystem of the SoC.

You need to have the development board with Intel (Altera) Cyclone V SoC. I used SoCKit board:


Ready? Let's go!
Total votes 13: ↑11 and ↓2 +9
Comments 2

Using PVS-Studio Static Analyzer in C and C++ Development for Embedded Systems

Reading time 4 min
Views 1.2K

This article will tell you how to launch analysis of an embedded project and how to work with the analyzer's report. The PVS-Studio analyzer supports a number of compilers for embedded systems. The current version allows checking projects built with one of the following compilers under Window, Linux, and macOS:

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Total votes 29: ↑27 and ↓2 +25
Comments 0

NodeMCU simple driver model (SDM) showcase: dynamic user interface

Reading time 8 min
Views 2.4K

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NodeMCU is an interactive firmware, which allows running Lua interpreter on the ESP8266 microcontroller (ESP32 support is in development). Alongside with all the regular hardware interfaces, it has WiFi module and SPIFFS file system.


This article describes the new module for the NodeMCU — sdm. SDM stands for simple driver model and it provides device-driver model abstraction for the system. In the first part of this article we will discuss the model itself and in the second part will be a showcase of dynamically created web user interface using sdm with some commentaries.

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Total votes 18: ↑17 and ↓1 +16
Comments 0

Stack-based calculator on the Cyclone IV FPGA board

Reading time 12 min
Views 9.7K

Introduction


As first-year students of Innopolis University, we had an opportunity to make our own project in computer architecture. University suggested us several projects and we have chosen to make a stack-based calculator with reverse polish notation. One of the requirements for the project is to use FPGA board provided by the university.



As our board, we have chosen Cyclon IV. Therefore, we had to write code on hardware description language. In the course we have studied Verilog, so we have chosen it. Also, the university has additional modules for FPGA, such as numpad, thus we decided to use it in our project.

In this article, we want to share our knowledge about FPGA and Verilog, also provide you with a tutorial to repeat our project.
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Total votes 75: ↑58 and ↓17 +41
Comments 27
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