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How to fix Arduino Uno COM3 error?

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 On Windows, a “COM3 error” with Arduino Uno usually means the PC can’t talk to the board on that serial port . Let’s go step by step from easiest to deeper fixes. I’ll assume you’re on Windows and using the Arduino IDE; if not, tell me your OS and I’ll adapt. 1. Basic checks (do these first) Unplug and replug the USB cable Use a different USB port on the PC. If possible, try a different USB cable (data cable, not a charge-only phone cable). Close anything else using COM ports Serial Monitor from another IDE Terminals like PuTTY, Tera Term, CoolTerm Manufacturer tools (ST-Link Utility, other dev tools) If another program has COM3 open, Arduino can’t use it. Restart the Arduino IDE Close IDE → reconnect Uno → then reopen IDE. 2. Make sure the right port is selected In Arduino IDE : Go to Tools → Port Look for something like: COM3 (Arduino Uno) or COMx (Arduino Uno) if it changed. Select the one that says Arduino Uno . ...
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What is the preferred way to install STM32CubeIDE on Linux?

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 The “normal” / preferred way is to use ST’s own Linux installer script for your distro, not random third-party packages. On Linux ST actually offers three bundles , all installed the same way:  ...rpm_bundle.sh → for Fedora / RHEL / CentOS / openSUSE (RPM-based) ...deb_bundle.sh → for Ubuntu / Debian (Deb-based) plain .sh → generic Linux (good fallback if the distro is too new and the deb/rpm bundle complains about deps) 1. Recommended installation (any distro, using ST installer) Go to the official STM32CubeIDE page and download the Linux installer for your architecture.  Open a terminal in the download folder. Make the installer executable (optional but nice): chmod +x st-stm32cubeide_*_amd64*.sh Run it with root privileges: sudo sh ./st-stm32cubeide_*_amd64*.sh Replace the * with whatever version string you downloaded, e.g. st-stm32cubeide_1.16.0_36100_20240131_1500_amd64.sh Follow the text-mode wizard (license, install ...
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How to practice with FPGA without a physical board?

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 You can get really good with FPGAs without ever touching a dev board, as long as you treat it like “real” hardware design and not just theory. Here’s a practical roadmap. 1. Learn HDL by Writing & Simulating Designs Pick one HDL to start: Verilog / SystemVerilog – very common in industry. VHDL – common in Europe & aerospace. (Later you can learn both; don’t juggle two at once.) Then use a simulator : Vendor tools (free editions): Xilinx Vivado’s built-in simulator (for Verilog/VHDL). Intel Quartus with ModelSim/Questa Starter. Open-source: GHDL (VHDL). Verilator (Verilog/SystemVerilog, very fast, good for bigger projects). Online playgrounds like EDA Playground (no install, great for quick experiments). Practice flow: Write a tiny module (e.g., 4-bit adder, counter, FSM). Write a testbench that: Drives inputs (clk, reset, data). Checks outputs with $display , assertions, or waveforms. Run simulation and i...
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How do i install QJoyPad on Raspberry Pi operating system?

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 You install QJoyPad on Raspberry Pi OS just like any other Debian package – it’s in the standard repos.  Here’s the quick way: 1. Update your package list Open a terminal on your Raspberry Pi and run: sudo apt update (This makes sure you see the latest versions in the repository.)  2. Install QJoyPad Still in the terminal: sudo apt install qjoypad That’s it – this pulls QJoyPad and any needed libraries from the Raspberry Pi OS repo.  QJoyPad is a Qt program that maps joystick/gamepad input to keyboard/mouse events under X11 (the normal Raspberry Pi desktop).  3. Run QJoyPad On Raspberry Pi OS with Desktop: Log into the graphical desktop. Either: Press Ctrl+Alt+T and run: qjoypad & Or find QJoyPad in the main menu (often under Games or Accessories , depending on your setup).  From there you can: Create a new layout . Click each button/axis and assign a key or mouse action. Save the layout (and optionally se...
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What is IAP in microcontroller?

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 In microcontroller context, IAP almost always means In-Application Programming . 1. Basic idea In-Application Programming (IAP) = The MCU can re-program its own Flash while your application code is running , without needing an external programmer (ST-Link, J-Link, etc.) or going into a separate factory programming mode. So instead of: PC → programmer → MCU (ISP / SWD / JTAG) you can do: PC / other device → your firmware → MCU’s Flash (via IAP) Your code acts as its own flash programmer . 2. IAP vs ISP vs bootloader ISP (In-System Programming) Usually means programming via a debug/programmer tool (JTAG/SWD, UART, etc.) Often uses a bootloader mode that runs instead of your application. Bootloader Small piece of code that runs first after reset. It may: Check for a new firmware image, Receive it over UART/USB/CAN/etc., Program it into Flash (using IAP services), Then jump to the main application. IAP The mechanism by whi...
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How to Install Arduino Libraries?

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 You install Arduino libraries in three main ways: via Library Manager, 2) by adding a ZIP, or 3) manually copying a folder. I’ll walk you through all three. 1. Install via Library Manager (easiest & recommended) Works for: Arduino IDE 1.8.x and 2.x Open the Arduino IDE . Go to: IDE 2.x: Sketch → Include Library → Manage Libraries… IDE 1.8.x: Sketch → Include Library → Manage Libraries… In the Library Manager window, type the library name into the search box (e.g. “Adafruit NeoPixel”, “AccelStepper”, “Servo”). Click the library you want, then click Install . Wait until it shows INSTALLED . How to use it after installing In your sketch, add: # include <LibraryName.h> Or go to Sketch → Include Library and select it from the list; the IDE will add the #include line for you. 2. Install from ZIP file Sometimes authors give you a .zip instead of publishing to Library Manager (e.g. GitHub repos). Download the .zip file ...
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What does RCC mean on STM32?

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 On STM32 , RCC stands for Reset and Clock Control . It’s a big central block inside the microcontroller that is responsible for: Clocks (the “C” in RCC) RCC generates and distributes clocks to: The CPU core Buses (AHB, APB1, APB2, etc.) Peripherals (GPIO, USART, SPI, I²C, TIM, ADC, etc.) Typical things RCC does: Select clock sources: HSI (internal), HSE (external crystal), PLL , LSI , LSE , etc. Set prescalers to divide clocks for different buses. Choose the system clock (SYSCLK) and derived clocks like HCLK, PCLK1, PCLK2. Resets (the “R” in RCC) RCC can reset: The entire chip (system reset) Individual peripherals (e.g. reset just USART1, SPI2, etc.) This is used to: Bring peripherals to a known default state Recover a misconfigured peripheral by toggling its reset bit. Enabling / disabling peripheral clocks Before you can use most peripherals on STM32, you must enable their clock in RCC . Examples: // HAL example ...
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