>>Create a USB Virtual COM Port Create a USB Virtual COM Port This article originally appeared in. COM ports have long provided a convenient way for PCs and embedded systems to exchange information. The traditional COM port on a PC is an RS-232 serial port on a motherboard or expansion card.

Implementing USB communication device. (CDC) can be used to emulate a serial port providing a. Awr Microwave Office Crack Free Download. Provides a description of the EFM32 USB Device stack.

Recent PCs often skip RS-232 in favor of USB. But with the right firmware, a USB device can appear as a virtual COM port that applications can access using.NET's SerialPort class or other COM-port APIs or libraries. This article will show how to design and program a USB virtual COM-port device using a general-purpose microcontroller with an embedded or external USB controller. The device uses standard USB class drivers included with Windows and other OSes. Options for Devices The COM-port software interface provides a way for PCs to exchange data with devices for any purpose.

A classic example is a modem that enables a PC to send and receive data over phone lines and responds to AT (Hayes modem) commands from the PC. Other COM-port devices support vendor-specific command sets for data acquisition, motor control, or other uses. To communicate with a COM port, an application first reserves the resource by opening the port.

For many devices, an application can also get and set port parameters such as bit rate, number of data bits per word, and flow-control method. The application reads and writes to the port as needed and when finished communicating, closes the port to allow other applications access to it. A USB virtual COM port is a software interface that enables applications to access a USB device as if it were a built-in serial port. Many USB virtual COM-port devices function as bridges that convert between USB and RS-232 or other asynchronous serial interfaces. But a virtual COM port doesn’t have to have a serial interface at all. Some virtual COM-port devices convert between USB and a parallel interface. Or a device might just read and store sensor data from an on-chip analog port and send the data to a PC via USB.

One way to create a virtual COM-port device is to use a dedicated chip such as FTDI’s FT232R USB UART. The chip handles all USB-specific communications in hardware and has an asynchronous serial port that can interface to a port on a microcontroller. FTDI provides drivers for Windows and other OSes. A similar chip is FTDI’s FT245R USB FIFO, which has a parallel interface instead of the serial port. Download Saint Seiya Movie 5 Sub Indo.

These chips are a quick way to add a USB port to a design. Many existing devices with asynchronous serial ports can use a USB UART to convert to USB with no firmware changes. Other companies with UART bridge chips include MosChip Semiconductor Technology Ltd., Prolific Technology, and Silicon Laboratories. The device I’ll describe takes a different approach. Install Cracked Steam 2009. The design doesn’t require a specific vendor’s USB controller or driver. The device can use a general-purpose microcontroller with an embedded USB controller or a CPU that interfaces to an external USB controller. The USB port can be full or high speed.

Device firmware manages USB communications and whatever other tasks the device is responsible for. Instead of a vendor-specific driver, the PC uses the USB communication devices class (CDC) driver included with Windows and other OSes. For Windows, an INF file matches the driver to the device. Several microcontroller vendors provide example firmware for USB virtual COM ports. The chips include Atmel Corporation’s AT89C5131, Microchip Technology’s PIC18F4550, and NXP Semiconductors’ LPX214x.

These examples are good starting points for projects. If you don’t have CDC example code for your CPU, you can base your firmware on other example code that transfers data using bulk or interrupt transfers. Any complete example firmware includes code for returning descriptors and responding to other control transfers and events on the bus. At the device, bulk and interrupt transfers are identical. The only difference is in how the host schedules the transfers.