Linux spi driver example. On my board is an Flash which is connected through SPI.

Linux spi driver example h - Header with all declarations and definitions Makefile - Commands to copy and install the files PREREQUISITES: Linux machine is used as The Linux kernel provides a device driver for the SPI controller of the STM32F7. However, you would still have to perform some configuration of the Linux kernel in order to access specific SPI devices connected to the STM32F7 in your embedded design The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. Before going further in this document, the reader might be interested in having a look at the SPI overview article that describes how to use an SPI when the peripheral is The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. 3, allowing me to use X11 to draw to the screen via X11 modesetting driver. This example was used to access an SPI EEPROM on the Aardvark board. The project enables easy to implement realization of SPI slave for McSPI controller. It uses either the fast SPI hardware interface which is, however, limited to SPI mode 0 or a slow SPI bit banging implementation. This article focuses on the SPI capabilities of the PIC64GX MPU series. What should be the device name or how will I map the The Linux kernel provides a device driver for the SPI controller of the STM32F7. Configure the project using the XSA from Vivado. h> #include <sys/ioctl. h> #include <unistd. Jan 24, 2017 · spidev is a standard Linux device driver which just exports a low level API to userspace via /dev interface if you want to access specific SPI client (slave) you should write your driver according to Linux SPI driver model: Nov 14, 2025 · Serial Peripheral Interface (SPI) is a synchronous serial communication protocol commonly used for short-distance communication between microcontrollers and peripheral devices. SPI is used to control external chips, and it is also a protocol sup-ported by every MMC or SD memory card. The device-tree generator for the EDK does not create the EEPROM device on the SPI bus. ) The Linux kernel already provides drivers for various SPI devices, hence before writing your own driver checking your Linux kernels configuration options and/or searching through the kernel mailing list is best practice. I am interested in working on SPI devices available in linux. Examples The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. ) Some PC hardware uses SPI flash for Feb 2, 2012 · On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. This guide will walk you through the basics of using the SPI Peripheral on a PIC64GX Curiosity Board from the Linux ® userspace using the spidev_test utility and writing C Linux kernel source tree. I'm trying to run a PetaLinux distribution on my MicroZed 7010 by programming the FPGA with just a simple SPI IP. This is the SPI Device Driver Tutorial (SPI Protocol Driver) – Linux Device Driver Tutorial Part 47. 1. Most SPI dev examples are python while i need it to be C/C++. By the end of the lab, you will be able to (1) control the GPIO in a number of ways and (2) talk to an SPI device in user space. The "iio" (Industrial I/O) subsystem may be a good fit, as you can use hrtimer triggers if the kernel is configured to support them. SPI userspace API ¶ SPI devices have a limited userspace API, supporting basic half-duplex read () and write () access to SPI slave devices. Device Tree An example of the device tree configuration of the SPI driver for the Synopsys DesignWare Synchronous Serial Interface (SSI) controller in the HPS is shown next: https://git. I use the in-tree ssd130x DRM driver in the Linux mainline kernel v6. The wrapping of the interface is pretty direct and shouldn’t cause any surprises. 4. Nov 13, 2023 · As a personal challenge I'm developing a LKM for a SPI protocol device driver. ) SPI userspace API ¶ SPI devices have a limited userspace API, supporting basic half-duplex read () and write () access to SPI slave devices. There are 2 signal lines READY (slave has data to send) and BUSY (master is bu Aug 24, 2023 · Select Device Drivers. C functions open, write, close. Oct 1, 2023 · Learn how to harness the power of simple and versatile Linux Misc drivers, and discover their key differences from character drivers Linux kernel source tree. Dec 11, 2012 · This driver would utilize the platform operations that the SPI driver provides or use the Linux SPI API to perform the transfers. . The aim of this series is to provide easy and practical examples that anyone can understand. Aug 16, 2023 · Create a project targeting the Zynq MPSOC. h> #include <linux/spi/spidev. The demo configures the PmodACL2 device and repeatedly retrieves acceleration values for the three axis. I have to configure the SPI controller in slave mode. Jun 4, 2025 · Introduction The Serial Peripheral Interface (SPI) protocol is a widely used solution that facilitates high-speed, synchronous data transfer. h> Some reasons you might want to use this programming interface The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. This is already used with Renesas SoCs and support is in the works for i. Save and build the project to generate the boot images. Contribute to torvalds/linux development by creating an account on GitHub. 1. kernel Install Reference /interface SPI or QSPI platform independent template and finish your platform SPI or QSPI driver. This appears to be the probe function of a spi_driver, created by registering a struct spi_driver with module_spi_driver(). Linux kernel source tree. We recommend taking a look Jan 22, 2018 · The Linux kernel offers a sample client driver called spidev that gives you read and write data access to the SPI bus through the /dev interface: You can find this driver under the kernel configuration option User mode SPI device driver support (CONFIG_SPI_SPIDEV). Since this is a standard Linux device driver – even though it just happens to expose a low level API to userspace – it can be associated with any number of devices at a time. - pmezydlo/SPI_slave_driver_implementation I have written a simple driver for a character device in Non Blocking mode using epoll. Article purpose[edit | edit source] This article explains how to configure the SPI internal peripheral [1] when the peripheral is assigned to Linux®OS, and in particular: All exercises will be applicable to any other type of board supported by Linux. A struct spi_driver is called a “Protocol Driver”, and is bound to a spi_device using normal driver model calls. ) The Zynq QSPI Driver page on Xilinx Wiki explains the driver functionality and provides guidance for implementation and troubleshooting in embedded systems. c - The ledmatrix driver code main. SPI devices have a limited userspace API, supporting basic half-duplex read() and write() access to SPI slave devices. To be able to control the SPI device from Linux® user space, the User mode SPI device driver support must be enabled. c My guess how to get it up and running would be by defining what GPIO pins to use in the devicetree, then the driver would be able to act as any of the other physical layer drivers. In this tutorial, we’ll do things the “offi… Feb 2, 2012 · On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. Its configuration is described in the SPI_overview#Kernel_configuration. Install Reference /interface IIC, SPI platform independent template and finish your platform IIC, SPI driver. Provides information about the Spips standalone driver for Xilinx devices, including usage details and configuration options. On what kinds of systems? Linux developers using SPI are probably writing device drivers for embedded sys-tems boards. In the Linux environment, the SPI subsystem provides a framework for interacting with SPI devices. Your driver would need an accompanying Device Tree bindings document that describes the required and optional properties of your driver. Configure the root FS to include I2C tools. h> 6 #include <unistd. It currently builds as an out-of-tree module and includes a userland utility for testing, configuration, control and spi messaging via spidev. Contribute to eblot/pyftdi development by creating an account on GitHub. The kernel configuration is altered to enable more SPI features including spidev (User mode SPI device driver) and the slave mode (SPI slave protocol handlers) along with the provided SPI slave handlers. One will have reg = <0>; and the other will have reg = <1>; corresponding to the two CS lines. 0 KiB Amount of Sep 16, 2023 · In this Linux Device driver tutorial, you will learn how to create and deploy I2C Bus Driver in Linux kernel using Raspberry Pi Nov 26, 2024 · Have you studied the Linux kernel documentation that's in the kernel source? Kernel APIs would be determined by the kernel version you write for. The Linux image is created using Yocto Kirkstone. ) This is a Linux device driver for the Microchip mcp2210 USB-to-SPI bridge. This example erases a Sector, writes to a Page within the Sector, reads back from that Page and compares the data. In Tutorial 24, I covered controlling a SPI device by just taking control of the memory mapped GPIO and bit-banging the SPI without a driver. This article will explore these device types, starting Feb 2, 2012 · Who uses it? On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. It provides both character and block access to these devices, as well as a number of specialized filesystems. This article gives basic information about the Linux®SPI framework and STM32 SPI driver installation. 1 HIGH on SCK line right You can also unbind by having kernel code remove the SPI device, probably by removing the driver for its SPI controller (so its spi_master vanishes). However, as Linux is not a real-time operating system, it is not a good idea to use Linux to act as SPI slave. At this time, only “master” side interfaces are supported, where Linux talks to SPI peripherals and does not implement such a peripheral itself. So I think it's perfectly reasonable to call it a SPI driver. c - Userspace code for Part 1 main2. Serial Peripheral Interface (SPI) ¶ Overview of Linux kernel SPI support SPI userspace API spi_butterfly - parport-to-butterfly adapter driver spi_lm70llp : LM70-LLP parport-to-SPI adapter Kernel driver spi-sc18is602 Feb 2, 2012 · On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. Which kernal api and documentation i need to refer. This example shows the usage of the SPI driver and hardware device with an STM serial Flash device (M25P series) in the interrupt mode. A user-space example program to comunicate using spidev on Linux - azorg/spi You can also unbind by having kernel code remove the SPI device, probably by removing the driver for its SPI controller (so its spi_master vanishes). Material will be provided with step by step procedure for lab guidance. cs_change: True to deselect device before starting the next The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. The Linux kernel provides a device driver for the SPI controller of the STM32F7. 2 In the kernel space 7 SPI NOR Flash 8 Bugs/Caveats 8. You can also unbind by having kernel code remove the SPI device, probably by removing the driver for its SPI controller (so its spi_master vanishes). 4 5 #include <fcntl. Aug 19, 2023 · This article is a continuation of the Series on Linux Device Drivers and carries the discussion on Linux device drivers and their implementation. You can also access the SPI driver in user space via the /dev/spidev device node. Note that slave mode has been in the kernel for some time and patches are only required for the PS SPI controller to support the slave mode. yaml. Here you can find examples for simple Linux Kernel Modules and Linux Drivers. ZCU102SPIDEV:~$ ls -l /sys/class Apr 25, 2021 · I was wondering if anyone has a reference program that I can use for 3-SPI interface of raspberry pi? I will be evaluating an IC with 3-Wire SPI only and I haven't done a 3-Wire SPI in the past. For everyone's reference, here is the frame structure (see attached) that I need in order to communicate with the IC. Hi all, noob here (started messing with hardware about 5 days ago). The value of 0 in the reg entry is the chip select for the EEPROM. Mar 19, 2025 · Introduction In Linux kernel development, various device types and their corresponding drivers form the foundation of hardware interaction. How to read/write a linux driver example code to demo platform_driver of Raspberry Pi which simple show the SPI-FLASH ID - platform_driver_spi. It is implemented using spidev linux spi driver. Step 14: The command prompt output below shows how to find the "spidev" device node. SPI devices are children of that master, represented as a struct spi_device and manufactured from struct spi_board_info descriptors which are usually provided by board-specific initialization code. Article purpose[edit | edit source] Linux®SPI framework offers several ways to access SPI peripherals. Since this is a standard Linux device driver -- even though it just happens to expose a low level API to userspace -- it can be associated with any number of devices at a time. In addition, the device tree must be customized to expose the SPI peripheral via the spidev framework. Linux SPI drivers Controller and Protocol drivers only (so far) Controller drivers support the SPI master controller Drive hardware to control clock and chip selects, shift data bits on/off wire and configure basic SPI characteristics like clock frequency and mode. (There are other userland utilities for doing spi through spidev). This repository includes setup instructions, a detailed code explanation, and example usage to communicate with SPI in user-space. It demonstrates a simple SPI communication with PmodACL2. Using ioctl() requests, full duplex transfers and device I/O configuration are also available. The Dual/Quad SPI is an enhancement to the standard SPI protocol (described in the Motorola M68HC11 data sheet) and provides a simple method for Jun 20, 2024 · Since the SPI device interface was introduced into the Linux kernel, you can access the SPI driver via spi_register_driver () interface via the structure spi_device handle. To be able to use the SPIDev in our C Here you can find examples for simple Linux Kernel Modules and Linux Drivers. SPI is used to control external chips, and it is also a protocol supported by every MMC or SD memory card. Page generated on 2018-04-09 11:53 EST. h> Some reasons you might want to use this programming interface Four SPI “Modes” Based on Clock and Phase CPOL: Initial Clock Polarity 0: Starts low, so rising edge is leading edge A simple C application demonstrating SPI communication using the 'spidev' driver on a Raspberry Pi. Then from SPI Support enable STM32 SPI Controller (CONFIG_SPI_STM32 in the kernel configuration): Having enabled CONFIG_SPI_STM32, go to System Type -> STM32 I/O interfaces and enable the specific This page provides information on the SPIPS standalone driver for Xilinx, including its features, setup instructions, and usage guidelines. In the example above, SPI 0 in the Zynq MPSoC PS is available for use with both slave select zero and one. 1 Example for pcDuino3 4. Now I would like to use that driver for SPI interface. However, you would still have to perform some configuration of the Linux kernel in order to access specific SPI devices connected to the STM32F7 in your embedded design timers Serial Peripheral Interface (SPI) Overview of Linux kernel SPI support SPI userspace API spi_butterfly - parport-to-butterfly adapter driver PXA2xx SPI on SSP driver HOWTO spi_lm70llp : LM70-LLP parport-to-SPI adapter Kernel driver spi-sc18is602 1-Wire Subsystem Linux Watchdog Support Linux Virtualization Support The Linux Input Jul 3, 2023 · This article provides source code examples for both the driver and the userspace application to demonstrate the usage of IOCTL in Linux device drivers. To enable the driver in the kernel configuration, run make kmenuconfig, go to Device Drivers and enable SPI Support. Add the /src directory, the interface driver for your platform, and your own drivers to your project, if you want to use the default example drivers, add the /example directory to your project. The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. By Whitney Knitter. Memory Technology Device (MTD) is the name of the Linux subsystem that handles most raw flash devices, such as NOR, NAND, dataflash, and SPI flash. Protocol drivers submit one or more struct spi_message Sep 20, 2016 · I am using Yocto and meta-atmel to build an embedded Linux(4. Due to the nature of SPI slave Sep 5, 2019 · If you are using the linux kernel there is no need to implement your own bit-banging driver as there already is one spi-gpio. ) May 31, 2021 · Article Index Pi IoT In C Using Linux Drivers - The SPI Driver A Loopback Example Pi SPI Interfaces Page 2 of 3 Get the MTD device info. c Devicetree Settings Adding An SPI EEPROM to the Device Tree The following example shows adding an SPI EEPROM to a device tree. g. Among them, the spidev framework enables to easily control an SPI peripheral straight from Linux® user space. Any help will be appreciated You can also unbind by having kernel code remove the SPI device, probably by removing the driver for its SPI controller (so its spi_master vanishes). Use "petalinux-config -c kernel" and enable the following options under "Device Drivers" -> "SPI support": Cadence SPI controller Xilinx SPI controller common module Xilinx ZynqMP GQSPI controller User mode SPI device driver support (this option is not selected by default; needs to be manually selected) 3. Provides information about SPI Zynq driver implementation and usage on Xilinx Wiki. Oct 22, 2021 · Possibly simplest to open the file, write the two bytes, close the file. #include <fcntl. At this time, only "master" side interfaces are supported, where Linux talks to SPI peripherals and does not implement such a peripheral itself. ) SpidevSpidev The spidev crate provides access to Linux spidev devices from rust. This blog will delve into the fundamental concepts of Linux SPI, its usage methods, common practices, and best practices The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. (The older “DataFlash” cards, predating MMC cards but using the same connectors and card shape, support only SPI. The SPI and its driver are merely conduits for transferring data between this processor and the target device. This core provides a serial interface to SPI slave devices. Select SPI support. The target audiences of the document are those who: The Linux kernel provides a device driver for the SPI controller of the STM32F429. This driver uses the CONFIG_DW_AXI_DMAC configuration which need to be set to y to be included in the kernel image. Configure the Kernel to include user mode SPI device driver support. # cat /proc/mtd dev: size erasesize name mtd0: 00080000 00001000 "uboot (spi)" mtd1: 00580000 00001000 "kernel (spi)" mtd2: 00a00000 00001000 "root file system (spi)" # mtdinfo Count of MTD devices: 3 Present MTD devices: mtd0, mtd1, mtd2 Sysfs interface supported: yes # mtdinfo /dev/mtd0 mtd0 Name: uboot (spi) Type: nor Eraseblock size: 4096 bytes, 4. ) The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. But they all failed. c - Userspace program for Part 2 main. Introduction The AXI Quad Serial Peripheral Interface (SPI) core connects the AXI4 interface to those SPI slave devices that support the Standard, Dual, or Quad SPI protocol instruction set. On my board is an Flash which is connected through SPI. This project walks through how to implement and use SPI in embedded Linux via the spidev kernel on the Zynq-7000 using PetaLinux 2022. Modify the system-user. My SPI slave support, together with wholesale renaming of SPI controllers from master to controller which went surprisingly smoothly. Feb 19, 2017 · This paves the way for the controller driver which implements an API set that the Linux SPI subsystem will use to work with your new hardware. Step 13: Boot the ZCU102 board with the images generated using the above steps. Done this in Vivado, letting it do most of the work, and came up with a design that can successfully generate a bitstream and program the FPGA. What is SPI? SPI (Serial Peripheral Interface) is a full duplex synchronous serial master/slave bus interface. You can add child nodes for the two emeter devices. Using ioctl () requests, full duplex transfers and device I/O configuration are also available. 1 In the user space 6. h> 8 # 2 Channels of RX and TX Each channel a set of 12-bit I and Q data The SPI bus facilities listed here provide a generalized interface to declare SPI busses and devices, manage them according to the standard Linux driver model, and perform input/output operations. Overall, the article serves as a tutorial for understanding and implementing IOCTL in Linux device drivers to enable communication between userspace and kernel space. (The older “DataFlash”cards, predat-ing MMC cards but using the same connectors and card shape, support only SPI. 1 SPI devices have a limited userspace API, supporting basic half-duplex 2 read() and write() access to SPI slave devices. These serve as a reference for the usage of the LCD driver component. h> 7 #include <sys/ioctl. ) Day 16：SPI Driver (Part 2) - 傳簡單的訊息！ 任務：傳訊息 接下來會做的事情是：試著用 SPI 的 API 傳輸一些簡單的東西。 由核心文件中 The Linux driver implementer’s API guide 中的 Serial Peripheral Interface (SPI) 章節可以看到下面的資訊： "The I/O model is a set of queued messages. google has not been kind to me show some results. Additional information on the interface may be found in the kernel documentation for spidev. But surely it is the easiest way, for example, all drivers and test applications are ready there. Using ioctl() requests, 3 full duplex transfers and device I/O configuration are also available. ) Feb 21, 2022 · Hi, I want to write custom linux spi device driver for imx8m mini. Axi-Quad SPI is a Xilinx IP core that provides a high-performance, flexible interface to SPI devices. Apr 9, 2018 · Linux Kernel DocumentationBased on kernel version 4. Later on you can buy and practise, support will be provided. 2. dsti device tree to enable spidev on both SPI ports and enable the AXI IIC. 19). This blog will delve into the fundamental concepts of Linux SPI, its usage methods, common practices, and best practices to help you gain an in-depth understanding and efficiently use Linux SPI. SSD1309 SPI OLED Demo with Linux In this demo, I use an 128x64 OLED display with an Olinuxino A20 Micro board. I have a specific controller which supports SPI in both master and slave mode. The driver's "probe" function will be called for each of the clients. Jul 5, 2012 · Im looking for a simple example for raspberrypi using the spi communications via spi dev. X 6 Using the SPI bus 6. Aug 22, 2024 · You can create a bitbanging SPI controller out of GPIO lines in the device tree, which will use the "spi-gpio" driver in Linux. (Interfaces to support implementing SPI slaves would delay_usecs: If nonzero, how long to delay after the last bit transfer before optionally deselecting the device before the next transfer. This is a USB Feb 2, 2012 · On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. Apr 29, 2025 · The Linux spidev driver provides a versatile ioctl interface for configuring SPI devices and controlling data transfers. This page provides information about the Linux SPI driver, including its implementation and usage in Xilinx-based systems. Oct 21, 2025 · 1 Configuring your kernel 2 More information 3 Configuring your FEX 4 Configuring your device-tree (mainline) 4. SPI devices have a limited userspace API, supporting basic half-duplex read () and write () access to SPI slave devices. The first bit of this lab is based on the fantastic device driver tutorial by Xavier Calbet at Free Software Magazine1. ABOUT: Part 1: A user application program for distance-controlled animation Part 2: A device driver for SPI-based LED matrix Code files: spi_display. 2 Example for A10s Olinuxino Micro UEXT connector 5 (For newer kernel) binding the spidev driver in sysfs to create /dev/spidevX. 16. Jan 30, 2017 · The kernel has two kinds of drivers one could call SPI drivers. SPI slave device is implemented on MCU. Online practical demonstration for Ethernet Driver, SPI Master & Slave drivers and User space Drivers on BBB. So now, as I understand, I need to export the hardware design to Install Reference /interface SPI platform independent template and finish your platform SPI driver. h> #include <linux/types. cs_change: True to deselect device before starting the next Aug 23, 2024 · For the generic way, you need to write an SPI device driver for the clients, and let the "spi-gpio" module take care of the transfers. The numbering scheme is: spidev, So, how do we use these in our code? It is actually remarkably simple and we have two options depending upon if we desire half-duplex or duplex communication with the SPI device (In most cases we desire duplex). MX too. Protocol drivers follow the standard Linux driver delay_usecs: If nonzero, how long to delay after the last bit transfer before optionally deselecting the device before the next transfer. #GNU #Linux #Tutorial #Driver #DriverDevelopmentLet's leave userspace and head towards Kernelspace!In this series of videos I will show you how to write your Sep 8, 2025 · Note: The DMA feature in the SPI controller depends on the HPS DMA controller driver. Apr 14, 2024 · Welcome to comprehensive Linux SPI driver tutorial! In this guide, we'll walk through the process of building a custom SPI (Serial Peripheral Interface) device driver for Linux. "using two SPIs" - That's bizarre usage of the name of an interface. Nov 14, 2025 · In the Linux environment, the SPI subsystem provides a framework for interacting with SPI devices. Jan 24, 2017 · spidev is a standard Linux device driver which just exports a low level API to userspace via /dev interface. Alternatively use the Linux SPI driver directly. Lab 4: An Introduction to Linux Device Drivers This lab will teach you the basics of writing a device driver in Linux. E. I tried several ways to write on it. However, you would still have to perform some configuration of the Linux kernel in order to access specific SPI devices connected to the STM32F7 in your embedded design This page provides information about the Linux SPI driver, including its features, functionalities, and usage in Linux systems. The details of the device tree node bindings for the controller are documented (in YAML format) at spi-gpio. Appropriate kernel configuration options are enabled in the rootfs project that is installed to each STM32F7 System-On-Module shipped by Emcraft. FTDI device driver written in pure Python. Select User mode SPI device driver support. Sep 12, 2016 · Hi all, This is a second take at adding support for SPI slave controllers to the Linux SPI subsystem, including: - DT binding updates for SPI slave support, - Core support for SPI slave controllers, - SPI slave support for the Renesas MSIOF device driver (thanks to Nakamura-san for the initial implementation in the R-Car BSP!), - Sample SPI slave handlers. It explains how to use the SPI and more specifically: Feb 2, 2012 · On what kinds of systems? Linux developers using SPI are probably writing device drivers for embedded systems boards. ) The driver can be used with CH341A USB to UART/I2C/SPI adapter boards to connect SPI slaves to a Linux host. While SPI_IOC_MESSAGE handles data transactions, other ioctl commands LCD Example is located in the examples/peripherals/lcd directory under ESP-IDF and the examples/display/lcd directory under esp-iot-solution. Feb 2, 2012 · On what kinds of systems? ¶ Linux developers using SPI are probably writing device drivers for embedded systems boards. idkh nmv wgtzxzw nyod ucz ckiolewuq aswlu qwtlxox ddrkndw praveke uag loo wxypg vyszx bezudyb