com.embeddedunveiled.serial.usb

Class SerialComUSB

java.lang.Object

com.embeddedunveiled.serial.usb.SerialComUSB

public final class SerialComUSB
extends Object

Encapsulates USB related operations and values.

An end product may be based on dedicated USB-UART bridge IC for providing serial over USB or may use general purpose microcontroller like PIC18F4550 from Microchip technology Inc. and program appropriate firmware (USB CDC) into it to provide UART communication over USB port.

[1] If your USB-UART converter based design is not working, consider not connecting USB connector shield directly to ground. Further, double check if termination resistors in D+/D- lines are really required or not.

Author:

Rishi Gupta

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEV_ADDED The value indicating that a USB device has been added into system.
static int	DEV_ANY The value indicating that the USB device can have any vendor id and product id.
static int	DEV_REMOVED The value indicating that a USB device has been removed from system.
static int	V_ALL Value indicating all vendors (vendor neutral operation).
static int	V_ATML Value indicating vendor - Atmel corporation.
static int	V_CYPRS Value indicating vendor - Cypress semiconductor corporation.
static int	V_EXAR Value indicating vendor - Exar corporation.
static int	V_FTDI Value indicating vendor - Future technology devices international, Ltd.
static int	V_MCHIP Value indicating vendor - Microchip technology Inc.
static int	V_MOSCHP Value indicating vendor - MosChip semiconductor.
static int	V_NXP Value indicating vendor - NXP semiconductors.
static int	V_PL Value indicating vendor - Prolific technology Inc.
static int	V_QHE Value indicating vendor - QinHeng electronics.
static int	V_RNSAS Value indicating vendor - Renesas electronics (NEC electronics).
static int	V_SLABS Value indicating vendor - Silicon Laboratories.
static int	V_TI Value indicating vendor - Texas instruments, Inc.
static int	V_WCH Value indicating vendor - WinChipHead.

Constructor Summary

Constructors

Constructor and Description
SerialComUSB(SerialComPortJNIBridge mComPortJNIBridge) Allocates a new SerialComUSB object.

Method Summary

Methods

Modifier and Type	Method and Description
SerialComUSBPowerInfo	getCDCUSBDevPowerInfo(String comPort) Read all the power management related information about a particular USB device.
String[]	getFirmwareRevisionNumber(int usbvid, int usbpid, String serialNumber) Gets the USB device firmware revision number as reported by USB device descriptor in its device descriptor using bcdDevice field.
int	getLatencyTimer(String comPort) Gets the current latency timer value for FTDI devices.
boolean	rescanUSBDevicesHW() Causes re-scan for USB devices.
boolean	setLatencyTimer(String comPort, byte timerValue) Sets the latency timer value for FTDI devices.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

V_ALL

public static final int V_ALL

Value indicating all vendors (vendor neutral operation).

See Also:

Constant Field Values

V_FTDI

public static final int V_FTDI

Value indicating vendor - Future technology devices international, Ltd. It manufactures FT232 USB-UART bridge IC.

See Also:

Constant Field Values

V_SLABS

public static final int V_SLABS

Value indicating vendor - Silicon Laboratories. It manufactures CP2102 USB-UART bridge IC.

See Also:

Constant Field Values

V_MCHIP

public static final int V_MCHIP

Value indicating vendor - Microchip technology Inc. It manufactures MCP2200 USB-UART bridge IC.

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Constant Field Values

V_PL

public static final int V_PL

Value indicating vendor - Prolific technology Inc. It manufactures PL2303 USB-UART bridge IC.

See Also:

Constant Field Values

V_EXAR

public static final int V_EXAR

Value indicating vendor - Exar corporation. It manufactures XR21V1410 USB-UART bridge IC.

See Also:

Constant Field Values

V_ATML

public static final int V_ATML

Value indicating vendor - Atmel corporation. It manufactures AT90USxxx and other processors which can be used as USB-UART bridge.

See Also:

Constant Field Values

V_MOSCHP

public static final int V_MOSCHP

Value indicating vendor - MosChip semiconductor. It manufactures MCS7810 USB-UART bridge IC.

See Also:

Constant Field Values

V_CYPRS

public static final int V_CYPRS

Value indicating vendor - Cypress semiconductor corporation. It manufactures CY7C65213 USB-UART bridge IC.

See Also:

Constant Field Values

V_TI

public static final int V_TI

Value indicating vendor - Texas instruments, Inc. It manufactures TUSB3410 USB-UART bridge IC.

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Constant Field Values

V_WCH

public static final int V_WCH

Value indicating vendor - WinChipHead. It manufactures CH340 USB-UART bridge IC.

See Also:

Constant Field Values

V_QHE

public static final int V_QHE

Value indicating vendor - QinHeng electronics. It manufactures HL-340 converter product.

See Also:

Constant Field Values

V_NXP

public static final int V_NXP

Value indicating vendor - NXP semiconductors. It manufactures LPC134x series of microcontrollers.

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Constant Field Values

V_RNSAS

public static final int V_RNSAS

Value indicating vendor - Renesas electronics (NEC electronics). It manufactures μPD78F0730 microcontroller which can be used as USB-UART converter.

See Also:

Constant Field Values

DEV_ANY

public static final int DEV_ANY

The value indicating that the USB device can have any vendor id and product id.

See Also:

Constant Field Values

DEV_ADDED

public static final int DEV_ADDED

The value indicating that a USB device has been added into system.

See Also:

Constant Field Values

DEV_REMOVED

public static final int DEV_REMOVED

The value indicating that a USB device has been removed from system.

See Also:

Constant Field Values

Constructor Detail

SerialComUSB

public SerialComUSB(SerialComPortJNIBridge mComPortJNIBridge)

Allocates a new SerialComUSB object.

Parameters:

mComPortJNIBridge - interface to native library for serial port communication.

Method Detail

getFirmwareRevisionNumber

public String[] getFirmwareRevisionNumber(int usbvid,
                                 int usbpid,
                                 String serialNumber)
                                   throws SerialComException

Gets the USB device firmware revision number as reported by USB device descriptor in its device descriptor using bcdDevice field.

Application can get this firmware revision number and can self adopt to a particular hardware device. For example if a particular feature is present in firmware version 1.00 than application create a button in GUI, however for revision 1.11 it creates a different button in GUI window.

Embedded system device vendors sometimes use bcdDevice value to indicate the 'embedded bootloader' version so that the firmware image flash loader program can identify the bootloader in use and use the appropriate protocol to flash firmware in flash memory. Typically, USB Device Firmware Upgrade (DFU) which is an official USB device class specification of the USB Implementers Forum is used.

On custom hardware the RTS and DTR pins of USB-UART device can be used to control GPIO or boot mode pins to enter a particular boot mode. For example, open the host serial port, make DTR low and RTS high and then reset microcontroller board. The microcontroller will see levels at its boot pins and will enter into a particular boot mode.

Parameters:

usbvid - USB vendor ID to match.

usbpid - USB product ID to match.

serialNumber - serial number of USB device (case insensitive, optional) to match.

Returns:

firmware number revision string on success.

Throws:

SerialComException - if an I/O error occurs.

getCDCUSBDevPowerInfo

public SerialComUSBPowerInfo getCDCUSBDevPowerInfo(String comPort)
                                            throws SerialComException

Read all the power management related information about a particular USB device. The returned instance of SerialComUSBPowerInfo class contains information about auto suspend, selective suspend, current power status etc.

Parameters:

comPort - serial port name/path (COMxx, /dev/ttyUSBx) which is associated with a particular USB CDC/ACM interface in the USB device to be analyzed for power management.

Returns:

an instance of SerialComUSBPowerInfo class containing operating system and device specific information about power management or null if given COM port does not belong to a USB device.

Throws:

SerialComException - if an I/O error occurs.

rescanUSBDevicesHW

public boolean rescanUSBDevicesHW()
                           throws SerialComException

Causes re-scan for USB devices. It is equivalent to clicking the "Scan for hardware changes" button in the Device Manager. Only USB hardware is checked for new devices. This can be of use when trying to recover devices programmatically.

This is applicable to Windows operating system only.

Returns:

true on success.

Throws:

SerialComException - if an I/O error occurs.

setLatencyTimer

public boolean setLatencyTimer(String comPort,
                      byte timerValue)
                        throws SerialComException

Sets the latency timer value for FTDI devices. When using FTDI USB-UART devices, optimal values of latency timer and read/write block size may be required to obtain optimal data throughput.

Note that built-in drivers in Linux kernel image may not allow changing timer values as it may have been hard-coded. Drivers supplied by FTDI at their website should be used if changing latency timer values is required by application.

Returns:

true on success.

Throws:

SerialComException - if an I/O error occurs.

getLatencyTimer

public int getLatencyTimer(String comPort)
                    throws SerialComException

Gets the current latency timer value for FTDI devices.

Returns:

current latency timer value.

Throws:

SerialComException - if an I/O error occurs.