USB Products


smxUSBD™

• Function Driver Layer provides USB functions to an application such as audio, mass storage, serial, and video.
• Device Core Layer provides the common USB device framework.
• Device Controller Driver Layer provides the interface to the selected USB device controller.
• Porting Layer provides service functions related to the hardware, OS, and compiler.

Function Drivers

The following sections describe each function driver and its API. The USB host is a Windows, Mac OS, or Linux system. See the smxUSBD User’s Guide for any limitations and implementation you must do for these.

Audio

The Audio function driver makes your device look like a sound card to the USB host. You can include a speaker and/or microphone in this audio device so you can playback and/or record sound. You can also integrate a MIDI port into your device so it can accept MIDI data. There is no need to install any driver or .inf file in Windows, Mac OS, or Linux to support this device but you may need to implement the sound device driver yourself, according to your system hardware and software environment.

sud_AudioIsConnected(port)
sud_AudioSendAudioData(port, pData, iLen)
sud_AudioGetAudioData(port, pData, iLen)
sud_AudioGetCurSpkSettings(port, pSettings)
sud_AudioGetCurMicSettings(port, *pSettings)
sud_AudioSendMIDIData(port, pData, iLen)
sud_AudioGetMIDIData(port, pData, iLen)
sud_AudioRegisterNotify(port, handler)
sud_AudioPackMIDIEvent(port, pData, pEvent)
sud_AudioUnpackMIDIEvent(port, pData, pEvent)

DFU

The DFU function driver allows updating the firmware in your device. The Windows operating system does not have a built-in driver for it, so you need to use a driver, such as the one provided by MDI or others that are commonly available. The DFU runtime function may be used as part of a composite device with other functions such as serial or mass storage. This is not a full firmware update solution. See the smxUSBD User’s Guide for details.

sud_DFUIsConnected()
sud_DFURegisterInterface (*pIF)
sud_DFUWriteDone (result, condition)
sud_DFUIsRuntimeMode()

Ethernet over USB

The Ethernet over USB function driver makes your device look like a network adapter to a Windows, MacOS, or Linux USB host. The host can communicate with this device via Ethernet data packets. Normally you need a TCP/IP stack on your device and use the APIs provide by this function driver to emulate an Ethernet device and add it to your network stack. This device has been integrated with smxNS, our TCP/IP stack. Then the host and your device can communicate with each other by TCP/IP with a USB cable instead of an Ethernet cable. One use of this is to allow configuring a device from the web browser on a host communicating with a web server on your device. This is especially useful if your processor has only a USB device controller and no Ethernet controller.

This driver supports CDC-ECM, CDC-NCM, and RNDIS for different host OSes. Windows supports RNDIS, and MacOS and Linux support ECM and NCM. RNDIS and either ECM or NCM can be enabled to support all three OSes, and the proper one is used at runtime when the device is plugged in. NCM supports packet aggregation.

int sud_NetIsPortConnected(port)
int sud_NetIsAggregationSupported(port)
int sud_NetWriteData(port, pBuf[], len[], packets)
void sud_NetRegisterPortNotify(port, handler)
void sud_NetSetEthernetAddr(port, pMACAddr)

HID Communication

The HID Communication function driver is useful for transferring small amounts of data. It is an alternative to the Serial function driver that does not require installing a driver or .inf file on Windows. It requires writing a special Windows application to communicate with it; a sample is provided.

sud_HIDIsConnected()
sud_HIDSendInput(*pDataBuf, size)
sud_HIDRegisterOutputNotify(handler)

Keyboard (Included)

The Keyboard function driver makes your device look like an HID keyboard to the USB host. It inputs key events to your PC.

sud_KBDInput(modifier, *key, count)
 
Mass Storage

The Mass Storage function driver makes your device look like a removable disk to the USB host. You can copy files to and from it.

sud_MSRegisterDisk(pDiskOper, lun)
 
Media Transfer Protocol (MTP)

The Media Transfer Protocol (MTP) function driver includes PTP support. It makes your device look like a digital still image device to the USB host. There is no need to install any driver or .inf file in Windows to support this device, but you may need to implement the file system interface (if not using smxFS) and the interface to get the properties of the files your device will support, such as the image width, height, etc.

MTP can also be used for general file transfer as an alternative to Mass Storage. Advantages are the ability to limit which files are accessed and that it is unnecessary to have two modes of operation to switch between local and USB access to the disk, to protect the file structure.

sud_MTPIsConnected(port)
sud_MTPRegisterInterface(pObjOper)
sud_MTPSendEvent(EventCode, iNumPar, *Par)

Mouse (Included)

The Mouse function driver makes your device look like an HID mouse to the USB host. It moves the mouse pointer on your PC.

sud_MouseInput(button, x, y, wheel)

Serial

The Serial function driver makes your device look like one or more COM ports to a Windows, Mac OS, or Linux USB host. You can use standard Win32 functions to communicate with the device, just like if it were connected to a real RS232 port. For the multi-port option, we provide a custom Windows USB serial driver, since the built-in Windows driver supports only one port. Our driver also allows using only 1/2 the number of endpoints, saving them for other uses.

sud_SerialIsPortConnected(port)
sud_SerialWriteData(port, pBuf, len)
sud_SerialDataLen(port)
sud_SerialReadData(port, pBuf, len)
sud_SerialSetLineState(port, iState)
sud_SerialGetLineState(port, piState)
sud_SerialGetLineCoding(port, pdwDTERate, pbParityType, pbDataBits, pbStopBits)
sud_SerialRegisterPortNotify(port, handler)

Video

The Video function driver makes your device look like a web camera to a Windows, Mac OS, or Linux USB host. There is no need to install any driver or .inf file in Windows to support this device but you may need to implement the camera sensor driver, and you may also need to customize the configuration of the driver for your real hardware features, such as the set of features your camera sensor will support.

sud_VideoIsConnected(port)
sud_VideoSendVideoData(port, pData, len)
sud_VideoGetVideoDataLen(port, len)
sud_VideoRegisterNotify(port, handler)


Composite Devices

smxUSBD allows creating a composite device. Such a device has multiple interfaces that are active at the same time using a single controller chip. For example, a composite device might combine serial and mass storage. See the smxUSBD User's Guide for more discussion of this.


Writing New Drivers

Contact us first to make sure we are not already working on the driver you need.

smxUSBD provides a function driver template and a section in the manual to help you write a new function driver, if needed.

smxUSBD provides a USB device controller driver template and a section in the manual, to help you write a new driver in case it does not support yours.
 

Porting

Little or no porting is necessary when smxUSBD is used with SMX®. It is designed to also work with other RTOSs and to run standalone, but it works best in a multitasking environment. The RTOS porting layer is handled by smxBase.

The hardware porting layer consists of two files, udport.h and udport.c. These files contain definitions, macros, and functions to port to a new processor. In addition, if the USB device controller is not among those already supported, a new driver will need to be written.


16-Bit Addressing Support

smxUSBD supports processors that can only do 16-bit memory addressing  (not byte addressing) such as the TI TMS320C55xx DSPs. These processors are difficult to support for typical communication protocols because of byte data and byte fields in standard protocol data structures. This support is enabled by a configuration option in smxUSBD.


Testing

We test smxUSBD with USBCheck Version 5.1 on a Windows PC to verify that it passes the Chapter 9 USB compliance tests for full speed and high speed. We also test with USBCV v1.3 and it passes the Chapter 9, HID, and MSC tests.

  
Code Size

Code size can vary greatly depending upon the processor, compiler, and optimization level.

All RAM used by smxUSBD for data is pre-allocated from the heap during initialization. Following is a table of RAM usage:

smxUSBD has one internal task in the device controller driver that uses about 1KB stack (or 2KB for MTP). Application tasks typically use 0.5 to 1.5KB depending on the function driver

Performance

Mass Storage
The following table shows mass storage performance using a RAM disk in the device.

Ethernet over USB
The following table shows Ethernet over USB performance for the indicated packet size and controller.

Serial
The following table shows the transfer rate for sending and receiving serial data for different application packet sizes and controllers.