Virtual usb emulators for computer. Create a virtual flash drive on your computer. Where can I buy Trioma

Development various devices based on microcontrollers is an activity worthy of a real computer geek. Undoubtedly, a useful feature of any gadget will be a USB interface for connecting to a computer. But what if the AVR chip does not provide hardware support for USB?

V-USB: size matters

When developing your own gadget, the problem of connecting it to a computer often arises. I must say that LPT and COM ports are now exotic on motherboards PCs, not to mention laptops, for which these interfaces disappeared a long time ago. Therefore modern computers There are practically no alternatives to the USB interface.

If the chip's resources are used one hundred percent, then it is better to immediately look towards devices with hardware support for the universal serial bus (such microcontrollers are present in the line of any manufacturer). In other cases, you can use software USB.

For Atmel microcontrollers there is a wonderful V-USB project that offers a software implementation of low-speed USB devices 1.1. The V-USB code will work on any AVR device that has at least 2KB of Flash memory and 128 bytes of RAM, with clock frequency 12; 12.8; 15; 16; 16.8 or 20 MHz.

The product can be used both under the open source GPL license and on a commercial basis. In order to develop your own USB devices, you usually also need to buy some sort of license. But the guys from V-USB took care of this too, purchasing a pair of Vendor ID - Product ID and allowing anyone to use them.

The hardware for connecting the USB bus to the microcontroller is very simple. If the device does not consume too much, then it can be powered directly from the bus (it is considered that the power line USB computer and is capable of delivering current up to 500 mA). Since the information lines (D+ and D–) use a signal level of 3.6 V, in addition to current limiting resistors, zener diodes are needed to match the 5 V logic of the chip. To indicate the type of connection, you need to “pull up” the supply voltage through a 1.5 kOhm resistance to line D–.

An alternative option for pairing via USB is to reduce the controller supply voltage using an appropriate stabilization chip or simply a pair of diodes. The latest diagram can be found on the V-USB project website.

USBtiny programmer

There are many different programmers for AVR microcontrollers. USBtiny is mentioned here in part because it contains a software implementation of USB similar to V-USB. The circuit of this programmer is simple: version 2 contains two microcircuits, and the first version contains only one (the ATtiny2313 chip itself). Thanks to detailed description on the website and with simple components, the device is easy to make even for a beginner. USBtiny is compatible with the popular avrdude program used for programming AVR microcontrollers.

The only problem is uploading the firmware into the programmer chip - for this you need... a programmer. If you have a computer with an LPT port, then you can make one of the options FBPRG aka “five wires”, which is

Preparing the sled

The software tools required to implement the simplest firmware for a USB gadget are extremely ascetic: the gcc-avr compiler, the avr-libc library, the avrdude programmer and the binutils set for AVR. On Debian/Ubuntu, everything you need is installed with one command:

$ sudo apt-get install avrdude binutils-avr gcc-avr avr-libc

On the vast expanses of the Internet it is not difficult to find very detailed guide via V-USB and libusb (in English). According to the manual, to add USB support to the project you will need the usbdrv folder from the archive with latest version V-USB. At the root of this folder there is a configuration template usbconfig-prototype.h. You need to make a copy of this file, calling it usbconfig.h. Next, fix usbconfig.h by specifying the port (D), the lines of which will be used for I/O, the line numbers D+ (2) and D– (3), as well as the frequency (12 MHz) at which the chip operates (ATtiny2313 ):

#define USB_CFG_IOPORTNAME D #define USB_CFG_DMINUS_BIT 3 #define USB_CFG_DPLUS_BIT 2 #define USB_CFG_CLOCK_KHZ 12000

To use a V-USB license for a device, you do not need to change the manufacturer and device numeric IDs. But you can choose symbolic names to your liking (they will allow you to distinguish several V-USB-based devices connected to the same computer):

#define USB_CFG_VENDOR_ID 0xc0, 0x16 #define USB_CFG_DEVICE_ID 0xdc, 0x05 #define USB_CFG_VENDOR_NAME "n","e","t","s","4","g","e","e","k" ,"s",".","c","o","m" #define USB_CFG_VENDOR_NAME_LEN 14 #define USB_CFG_DEVICE_NAME "U","S","B","e","x","a" ,"m","p","l","e" #define USB_CFG_DEVICE_NAME_LEN 10

Various gadgets

Do you have an idea for any device? Don’t rush to solder and code, but look, maybe someone has already done something similar. If you can’t use ready-made diagrams and sources, then at least you won’t have to start everything from scratch.

For example, the V-USB project, thanks to its licensing policy, has accumulated a decent base of ready-made (including freely distributed) solutions. Here you can find various implementations of keyboards, USB adapters for joysticks, gamepads (including rare ones, for example SNES/NES, Nintendo 64, ZX Spectrum joystick, Sony PlayStation 1/2) and the like. DMX adapters, virtual COM and UART ports, i2c, Servo, DCF77, IR wireless interfaces - everything that will help you connect more new devices to your PC. Loggers, platforms for probes and sensors, adapters for LCD displays, programmers and loaders can also be useful in the household.

The program for the chip is elementary!

When interacting via a USB bus, the computer is the main device that periodically sends control request messages. The controller, accordingly, is a slave and must respond to requests. The control message format is determined by the usbRequest_t structure from the usbdrv.h file:

Typedef struct usbRequest ( uchar bmRequestType; uchar bRequest; usbWord_t wValue; usbWord_t wIndex; usbWord_t wLength; ) usbRequest_t;

Let's create a file main.c at the same level as the usbdrv folder and describe the necessary header files, definitions and variables in it:

#include #include #include #include "usbdrv.h" #define F_CPU 12000000L // MK frequency #include #define DATA_OUT 1 // Send command #define DATA_IN 2 // Receive command // Buffer static uchar replyBuf = "Hello World!"; static uchar dataLength = 0, dataReceived = 0;

In main.c we will override the usbFunctionSetup function, which is called automatically when a new request is received:

USB_PUBLIC uchar usbFunctionSetup(uchar data) ( usbRequest_t *rq = (void *)data; switch(rq->bRequest) ( case DATA_OUT: // Process the command to send data usbMsgPtr = replyBuf; // Specify the buffer return sizeof(replyBuf); / / Return the buffer size case DATA_IN: // Processing the data receiving command dataLength = (uchar)rq->wLength.word; // Get the length dataReceived = 0; // There will be many calls to usbFunctionWrite if(dataLength > sizeof(replyBuf)) // Checking for overflow dataLength = sizeof(replyBuf); return USB_NO_MSG; // Return 255 ) return 0; )

As you can see from the listing, the easiest way to send data to a computer is to set usbFunctionSetup to the value of the usbMsgPtr pointer to the RAM buffer (replyBuf) where the data is located, and then return its length. The buffer size should not exceed 254 bytes. For the ATtiny2313 with its 128 bytes of RAM, this is enough. For more functional devices, there is a second way - overriding the usbFunctionRead function.

To get the data, first, you need to use the usbFunctionSetup function to extract the message length from the wLength field of the request and store it in the dataLength global variable. Secondly, in main.c you need to override the usbFunctionWrite function, which is designed to process the received data and is called automatically (and obviously several times) if usbFunctionSetup returns the value USB_NO_MSG (255):

USB_PUBLIC uchar usbFunctionWrite(uchar *data, uchar len) ( uchar i; // Save the received portion of data to a buffer for(i = 0; dataReceived< dataLength && i < len; i++, dataReceived++) replyBuf = data[i]; return (dataReceived == dataLength); }

Actually, the usbFunctionWrite function fills the replyBuf buffer with the received data.

By the way, for this method to work, you need to make changes to usbconfig.h:

#define USB_CFG_IMPLEMENT_FN_WRITE 1

Well, the last function of the firmware is main:

Int main() ( usbInit(); // Initialize USB usbDeviceConnect(); // Connect the device sei(); // Enable interrupts // Wait for control messages in an infinite loop while(1) usbPoll(); return 0; )

Let's use USART/UART

A good alternative to software/hardware USB is to use the popular USART/UART interface in the chip with a third-party converter of this protocol to USB, which can be made, for example, based on the FT232RL chip.

Libusb: neither clothed nor naked

You may ask: will you have to write a driver for the computer operating system in order to connect a USB device? If you use libusb, you can do without implementing a full-fledged kernel module. Libusb is an open source library that allows you to quickly program, firstly, searching for a device on the bus, and secondly, exchanging data with it.

Under Linux, the library and the necessary header files can be obtained from the source codes. It's better to use the standard repository of your distribution. For Debian/Ubuntu, for example, like this:

$ sudo apt-get install libusb-dev

There is also a libusb port for Windows - libusb-win32. Contrary to the name of the project, 64-bit operating systems from Microsoft are also supported (starting from version 1.2.0.0).

But libusb is a separate topic of discussion. I think you are familiar with PC programming and can figure it out on your own. So I'll be brief. Create a file usbtest.c and start filling it with content. First the necessary header files and definitions:

#include [...] // For a computer, the meaning of the commands is reversed, // but the designations remain the same #define DATA_OUT 1 #define DATA_IN 2

The usbOpenDevice function to initialize the device:

Usb_init(); // Initialize USB usb_find_busses(); // Find buses usb_find_devices(); // Find devices // Enumerate all buses for(bus=usb_get_busses(); bus; bus=bus->next) ( // Enumerate all devices on the bus for(dev=bus->devices; dev; dev=dev-> next) ( // If the vendor and product IDs do not match... if(dev->descriptor.idVendor != vendor || dev->descriptor.idProduct != product) continue; // ...skip this iteration // Try to get a device handle if(!(handle = usb_open(dev))) ( fprintf(stderr, "%s\n", usb_strerror()); continue; ) return handle; // Return handle ) ) // Device not found return NULL;

As you can see, the usbOpenDevice parameters are the numeric identifiers of the manufacturer and device. If the device is present on the bus, its descriptor is returned. If there are several devices on V-USB, you will have to add a check for the symbolic names of the vendor and product.

And the main function of the usbtest console utility:

Int main(int argc, char **argv) ( // Device descriptor usb_dev_handle *handle = NULL; int nBytes = 0; char buffer; // Looking for the device handle = usbOpenDevice(0x16C0, 0x05DC); if(handle == NULL) ( fprintf(stderr, "Could not find USB device!\n"); exit(1); ) // Argument out - get data from the chip if(strcmp(argv, "out") == 0) ( nBytes = usb_control_msg (handle, USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_ENDPOINT_IN, DATA_OUT, 0, 0, (char *)buffer, sizeof(buffer), 5000); printf("Got %d bytes: %s\n", nBytes, buffer); // Argument in - send string (next argument) ) else if(strcmp(argv, "in") == 0 && argc > 2) ( nBytes = usb_control_msg(handle, USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_ENDPOINT_OUT, DATA_IN, 0, 0, argv, strlen(argv)+1, 5000); ) if(nBytes< 0) fprintf(stderr, "%s\n", usb_strerror()); usb_close(handle); // Закрыть дескриптор return 0; }

The usb_control_msg function, which is declared in the usb.h include file, rules the roost here. It has a bunch of parameters and actually creates those control messages, the processing of which is implemented in the microcontroller firmware.

Proteus is resting

Everyone's favorite electrical circuit simulator, Proteus ISIS, is useless when developing software-based USB devices. Its USB emulator only supports chips with Universal Serial Bus hardware support (such as AT90USB646 or AT90USB1286).

We assemble, flash, test

Below is a small but very useful Makefile, with which you can easily get the firmware for the chip - main.hex and the usbtest utility binary using the make command from main.c and usbtest.c:

CC = avr-gcc OBJCOPY = avr-objcopy CFLAGS = -Wall -Os -Iusbdrv -mmcu=attiny2313 OBJFLAGS = -j .text -j .data -O ihex OBJECTS = usbdrv/usbdrv.o usbdrv/oddebug.o usbdrv/usbdrvasm .o main.o CMDLINE = usbtest # Goal: collect everything all: main.hex $(CMDLINE) # Build a utility for the computer $(CMDLINE): usbtest.c gcc -I ./libusb/include -L ./libusb/lib /gcc -O -Wall usbtest.c -o usbtest -lusb # Clear the project from binary code clean: $(RM) *.o *.hex *.elf usbdrv/*.o # Obtaining the firmware file from the elf file %. hex: %.elf $(OBJCOPY) $(OBJFLAGS) $< $@ # Сборка elf-файла main.elf: $(OBJECTS) $(CC) $(CFLAGS) $(OBJECTS) -o $@ # Сборка файлов библиотеки V-USB $(OBJECTS): usbdrv/usbconfig.h # C в объектный код %.o: %.c $(CC) $(CFLAGS) -c $< -o $@ # asm в объектный код %.o: %.S $(CC) $(CFLAGS) -x assembler-with-cpp -c $< -o $@

To upload the firmware to the microcontroller using the usbtiny programmer, type the command:

$ sudo avrdude -p t2313 -c usbtiny -e -U flash:w:main.hex:i -U lfuse:w:0xef:m

In avrdude, fuse settings are not very clear, but they can be easily calculated in one of the online calculators.

We connect the device to the computer and check how it works (usbtest with the out parameter reads the line, in - writes the specified line to the chip buffer):

$ sudo ./usbtest in all_ok $ sudo ./usbtest out

A spoon of tar

Software USB is not a panacea. Software implementations usually have a number of simplifications, such as the lack of checking the checksum and channel symmetry, which negatively affects noise immunity. Also, software libraries usually use low-speed USB operating modes. And the USB library code eats up the chip’s already small memory.

Let's peek...

At the logic level, the USB protocol is essentially multi-level packet data transfer. It’s easy to verify this (and at the same time learn a lot of interesting things about USB) by using the Wireshark network protocol analyzer. You must first download the USB monitor driver:

$ sudo modprobe usbmon

You can now select USB buses from the Wireshark interface list. You can view the device bus number, for example, in the logs.

Conclusion

I hope that after you have learned how to transfer data between your computer and the AVR microcontroller, your passion for electronics will flare up with renewed vigor, giving rise to many original and useful devices. All that remains is to wish you success in this difficult but interesting field.

Sometimes a situation arises when you need a flash drive, but you don’t have it at hand. For example, some accounting and reporting programs require an external drive. In such a situation, you can create a virtual storage device.

Using special software, this can be done in several ways. Let's look at each of them step by step.

Method 1: OSFmount

This small program is very helpful when you don’t have a flash drive at hand. It works on any version of Windows.

After you have downloaded the program, do this:

Additional features may be required to use this program. To do this, you need to enter the item in the main window "Drive Actions". Then it will be possible to use the following options:

• Dismount – unmount the volume;
• Format—volume formatting;
• Set media read-only – prohibits recording;
• Extendsize – expands the size of the virtual device;
• Savetoimagefile – used to save in the required format.

Method 2: Virtual Flash Drive

A good alternative to the method described above. When creating a virtual flash drive, this program allows you to protect the information on it using a password. The advantage of this is that it works in older versions of Windows. Therefore, if you have a version of Windows XP or lower on your computer, this utility will help you quickly prepare a virtual storage device on your computer.

Instructions for using this program look like this:

1. Download and install Virtual Flash Drive.
2. In the main window, click the button "Mount new".
3. A window will appear "Create new volume", specify the path to create virtual media in it and click "OK".

As you can see, the program is very easy to use.

Method 3: ImDisk

This is one of the most popular programs to create a virtual floppy disk. Using an image file or computer memory, it creates virtual disks. When using special keys when loading it, the flash drive will appear as a virtual removable disk.

Method 4: Cloud storage

The development of technology makes it possible to create virtual flash drives and store information on them on the Internet. This method is a folder with files that is accessible to a specific user from any computer connected to the Internet.

Such data storages include Yandex.Disk, Google Drive and Mail.ru Cloud. The principle of using these services is the same.

Let's look at how to work with Yandex Disk. This resource allows you to store information on it up to 10 GB for free.

Working with such a virtual storage medium allows you to fully manage your data: group it into folders, delete unnecessary data, and even share links to it with other users.

What is it and why is it needed?
If the radio in your car has an input for a CD changer, you can connect a similar adapter to it, it will fool the radio and it will think that a changer is connected to it, and instead of discs, a regular flash drive with music is used. The adapter can be controlled by standard means, including control from the steering wheel.

There have already been several reviews of similar adapters on Muska, the most famous being the Chinese Yatour.

I decided to go an unconventional route, I decided to try the Russian Trioma Flipper 2.
Overall rating - excellent, satisfied with the purchase, recommend.

For details please see below

Preface

If your car has a regular radio that is not connected to controlling any functions of the car, the easiest way is to just buy a new radio. Branded radio with USB input can be bought within a hundred euros. Another amount will have to be spent so that it understands steering wheel controls.

You can hack it and attach an AUX (audio) input, but you will still need a sound source, and you will have to forget about steering wheel controls.

I abandoned the options with FM transmitters a long time ago - I tried a couple of different transmitters, the sound quality was not very good.

There is another way: connect an adapter to the radio at the input of the CD changer, which will allow you to listen to music from flash drives, controlling the adapter using the standard means of the radio, including from the steering wheel. You can find similar adapters from different manufacturers with different parameters and differing in quality, reliability, convenience or price.
The most famous adapter is Yatour. The coolest, perhaps, is the American Grom Audio, which plays, among other things, FLAC. Well, there are a few more devices - Audiolink, Xcarlink, DMC, Dension.

First of all, I started looking at yatour. On Ali it costs from $50. But reviews on the Internet dampened the enthusiasm a little. The adapter has a linear output with a fixed level, so on many radios the volume level is noticeably lower than from the radio. Sometimes unstable operation, freezes, criticality to the presence of foreign files on the flash drive. Number of supported directories - how many disks the radio supports, in my case it is 6.

Yatour does not have an official website; Yatour's websites on the Internet are sellers' websites. And the information has to be collected bit by bit in different places, mostly those who installed it themselves write back, but their experience is not always suitable for your radio.
But I was lucky, I came across a Belarusian seller yatour Sergei aka SSD, who answered all my questions, including the features of working with my radio.
In general, it works, but there may be problems with volume and unstable operation. It was from Sergei that I first heard about Grom Audio and Triome, which he also sells.

Grom Audio on Android, supports FLAC, but there is no model for my car.

But Trioma Flipper 2 interested me. First of all, the ability to adjust the output level (volume). In addition, it has a much more convenient organization of folders and there can be many more of them. And it's much less buggy.
By borrowed good table comparisons between Yator and Trioma


Clarification on Yaturs:
1. Extraneous files do not interfere with playback. At least on some firmwares.

So, I made my choice. Trioma!!!
When purchasing such an adapter, be sure to choose a model for your car. More precisely, under the car radio of your car. Different radios may have different connectors for the changer that are not compatible with each other.

Where can I buy Trioma?

I started looking for friends who could bring me an adapter from Russia or Belarus. Found!!! I found a friend from Russia who ordered and already brought me an adapter at the beginning of February! Oleg, thank you!

And here is the adapter at my home!

A few more photos

Connector for connecting additional devices, AUX cable or bluetooth adapter


Mom on adapter


Dad on cable


Connector for radio RD4


Do not open, guarantee

Installation

There are two suitable connectors at the back, one of them will not work - checked;)
The photo shows the required connector. It already has wiring for connecting the changer, so we pull out the installed connector and turn on ours.


We connect the cable with the adapter, turn on the ignition and miracle - everything worked immediately!!! Moreover, the volume level is approximately the same as from the built-in CD.

But then we begin to think about where to connect the USB cable. The easiest way in my case turned out to be to route the cable under the steering wheel into the small glove compartment to the left of the driver.


The adapter itself was put into a niche behind the left of the radio. There is not much space there; after installing the radio in place, the adapter was clamped there with cables, so there was no need to secure the adapter additionally.

On all forums they write that the radio requires activation of the changer in the service. For me, everything turned out to be much simpler. After turning on, the radio itself determined that a changer was connected to it and it became possible to select it through the input switch (radio/CD/changer).
As it turned out, activation is needed not for the radio, but for the display so that it can reflect information for the changer.
But six months ago I and the Chinese, well done, sent a display with all the activated functions. So everything worked for me without additional activation.

Adapter operation

The adapter understands 32 directories, which can have 32 subdirectories, each of which can contain up to 99 files. But I soon realized that my disc switch only switches the first six discs. Although in Random mode the adapter sees all directories.

I asked a question on the Trioma forum, support responded very quickly and offered options for organizing directories. The problem turned out to be that on the RD4 the buttons, although they perform the Disc+/Disk- function, in reality they send commands to directly select disk 1-6 to the adapter. So these buttons can only switch 6 root directories or 6 subdirectories.
And it’s not possible to manage 1024 directories on my radio. You can manage only 32*6=192 directories;)

The description says that the FF/FR buttons perform a dual function - changing directories/subdirectories and rewinding.
But on the RD4 Track+/Track- are combined with FF/FR and for the adapter these buttons have a triple purpose:
1. Short press - Track+/Track-
2. Press for 2-3 seconds, release when the sound will disappear from the current track - switch directory
3. Long press >3 seconds, there is an accelerated muffled sound - rewind
The time is approximate, you need to focus on the sound

Even before the purchase, I assumed that I would store one large megaflash drive with hundreds of catalogs. But now I see that it is more convenient to have several flash drives with different selections.
I have this now:
1. Russian pop music 80-90s
2. Foreign pop music 80-90s
3. Instrumentals

Total. For relatively little money, I got a glitch-free adapter with good sound quality and simple, intuitive controls. I am very pleased with the purchase, Trioma - well done!!!

Additional links

Mini FAQ

• What needs to be done to ensure that the names (file names, tags, or anything at all) are shown on the display?
• Triom adapters certainly “see” tags, file names, and folder names. Where possible, they display text strings on the standard displays of radios: BMW and all cars with an optical MOST bus. Perhaps soon text output will be implemented for some Toyota/Lexus devices.
• CD changers do the job without any problems.
• I'm afraid you are mistaken: we do not know any external changers other than the models listed above that cope with this task. Changers built into the head unit are a different matter, where the text is output directly to the display controller - this is a completely different mechanism.
• Is it possible to connect additional devices to the Trioma Flipper 2 adapter?
• You can connect either an AUX-minijack 3.5 male adapter cable to the adapter