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IMPLEMENTINGUSB COMMUNICATIONDEVICECLASS

(CDC) ONS iM3U1XXMCUS

1. IntroductionUSB revolutionized the PC peripheral space by making a very simple plug-and-play interface for users. As a result,

many modern computers no longer support RS-232 serial COM ports, opting for the slimmer USB alternative. This

can be an issue for the developer who needs a COM port for communication between a peripheral and host PC. A

subset of the USB Communication Device Class (CDC) can be used to emulate a serial port providing a virtual

COM port UART interface. This allows developers to use legacy applications with new products using the same

COM port interface as before, with few hardware and software modifications.

Figure 1. USB CDC Virtual COM Port System

This application note describes the USB communications device class driver (or USB CDC) in detail and includes

an implementation example for the Silicon Labs SiM3U1xx MCU.

1.1. Assumptions

This document assumes the following: A working knowledge of the C programming language.

Familiarity with the USB 2.0 specification and terms and abbreviations defined by the USB specification.

Familiarity with Silicon Labs SiM3U1xx development environment.

1.2. Features and Limitations

The CDC firmware implemented with this application note includes the following features:

Emulates a serial COM port on PC that supports the CDC Abstract Control Model (ACM).

Provides an abstract communication interface for data transfers between the host and the device.

Handles standard Chapter 9 USB device requests.

Handles CDC-specific requests from USB host.

Notifies the USB host of status using an interrupt endpoint. Provides data communication with the USB host using a bulk endpoint.

The following baud rates are supported: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400,

460800, and 921600 bps.

The example does not implement the following:

No CTS/RTS control is performed, so flow control must be set to nonein the terminal program.

RTS/DTR control is not implemented.

Serial Device

Host PC USB cable SiM3U1xxRS232

cableEnd device

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2. Relevant Documentation

Precision32 Application Notes are listed on the following website: www.silabs.com/32bit-appnotes.

AN667: Gett ing Started with the Si li con Labs Prec is ion32 IDEprovides a description of the IDE

features and environment.

AN670: Gett ing Started with the Sili con Labs Precision32 AppBui lderprovides a description of the

AppBuilder features.

3. USB CDC Class

The USB communications device class (CDC) is a composite USB device class, and the class may include more

than one interface. The CDC is used primarily for modems, but also for ISDN, fax machines, and telephony

applications for performing regular voice calls.

The Abstract Control Model subclass of CDC and bridges the gap between legacy modem devices and USB

devices, enabling the use of application programs designed for older modems.

3.1. Class Requests

The class requests and class notifications supported are listed in Table 1.

These class-specific requests are used for device and call management.

3.1.1. Set Line Coding

This request allows the host to specify typical asynchronous line-character formatting properties.

Table 2defines the line coding properties.

Table 1. Abst ract Cont rol Model Requests

Request Code Description

SET_LINE_CODING 20h Configures baud rate, stop-bits, parity, and number-

of-character bits.

GET_LINE_CODING 21h Requests current DTE rate, stop-bits, parity, and

number-of-character bits.

SET_CONTROL_LINE_STATE 22h RS232 signal used to tell the DCE device the DTE

device is now present.

bmRequestType bRequest wValue wIndex wLength Data

00100001b SET_LINE_CODING 0 interface size of

structure

line coding

structure

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3.1.2. Get L ine CodingThis request allows the host to find out the currently configured line coding. Table 2 defines the line coding

properties.

3.1.3. Set Control L ine State

This request generates RS-232/V.24 style control signals. Table 3defines control signal bitmap.

Table 2. Line Coding Format

Offset Field Size Value Description

0 dwDTERate 4 Number Data terminal rate, in bits per second.

4 bCharFormat 1 Number 0: 1 Stop bit1: 1.5 Stop bits

2: 2 Stop bits

5 bParityType 1 Number Parity:

0:None

1: Odd

2: Even

3: Mark

4: Space

6 bDataBits 1 Number Data bits (5, 6, 7, 8 or 16).

bmRequestType bRequest wValue wIndex wLength Data

10100001b GET_LINE_CODING 0 interface size of

structure

line coding

structure

bmRequestType bRequest wValue wIndex wLength Data

00100001b SET_LINE_CON-

TROL_STATE

control signal

bitmap

interface 0 none

Table 3. Contro l Signal B itmap

Bit Posit ion Descript ion

15:2 Reserved (Reset to zero).

1 Carrier control for half duplex modems. This signal corresponds to V.24 signal

105 and RS232 signal RTS.0: Deactivate carrier.

1: Activate carrier.

The device ignores the value of this bit when operating in full duplex mode.

0 Indicates to DCE if DTE is present or not. This signal corresponds to V.24 signal

108/2 and RS232 signal DTR.

0: DTE is not present.

1: DTE is present.

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3.3. Endpoint Configuration

Table 6illustrates the endpoint configuration for the Abstract Control Model.

Figure 2shows a standard CDC communication flow.

Figure 2. USB CDC Communication Flow

Table 6. UART State Bi tmap

Endpoint Direction Type Max Packet

Size

Description

EP0 In/Out Control 64 Standard requests, class requests.

EP1 In Interrupt 16 State notification from device to host.

EP2 In Bulk 64 Data transfer from device to host.

EP3 Out Bulk 64 Data transfer from host to device.

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4. Firmware Example Overview

The firmware example included with this application note contains the driver, USB stack for the SiM3U1xx, and PC-

side application layer code.

4.1. File Organization

The files included in the USB CDC example are as follows: generateddirectory containing SiM3U1xx hardware initialization files

VirtualSerialdirectory containing the virtual COM demo files

CDC_ACM.infUSB CDC INF file

Descriptors.cVirtual COM USB descriptors

LUFAConfig.hProject configuration

VirtualSerial.cprimary application file

LUFASiM3L1xx USB stack firmware

Commoncommon header files

DriversUSB driver files

Miscmiscellaneous files

USBUSB stack files

ClassUSB class files

DeviceUSB device class files

AudioClassDevice.*USB audio class implementation

CDCClassDevice.*USB CDC class implementation

HIDClassDevice.*USB HID class implementation

MassStorageClassDevice.*USB mass storage class implementation

MIDIClassDevice.*USB MIDI class implementation

RNDISClassDevice.*USB RNDIS class implementation

HostUSB host class files, not implemented by the SiM3U1xx

Commoncommon driver files

CoreUSB Chapter 9 handler files

SiM3USiM3U1xx USB hardware control firmware files Device_SIM3U.*USB device definitions

Endpoint_SIM3U.*USB endpoint transition control

EndpointStream_SIM3U.*USB endpoint stream transition control

USBController_SIM3U.*USB controller definitions

USBInterrupt_SIM3U.*USB interrupt handler

USB.hUSB header file

main.c

4.2. LUFA USB Stack

The USB CDC firmware example is based on the LUFA open-source project. LUFA is an open-source complete

USB stack released under the permissive MIT License. It includes support for many USB classes, both for USB

Hosts and USB Devices. For USB Devices, the LUFA stack includes support for Audio Class, CDC Class, HIDClass, Mass Storage Class, MIDI Class, and RNDIS Class.

More information about the LUFA project can be found on the official website: http://www.fourwalledcubicle.com/

LUFA.php.

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5. Detailed List of Functions

This section discusses the detailed function declarations in the CDC USB stack firmware example.

5.1. CDC Functions

This section focuses on the functions found in the CDCClassDevice.c and CDCClassDevice.h files

(AN758_USB_CDC\src\LUFA\Dri vers\USB\Class\Dev icedirectory). This file implements the USB CDC deviceclass.

5.1.1. CDC_Device_Process_ControlRequest

Handle USB CDC special class request.

Syntax

voi d CDC_Devi ce_ProcessCont r ol Request ( USB_Cl assI nf o_CDC_Devi ce_t * const

CDCI nt er f aceI nf o)

Parameters

CDCI nt er f aceI nf o: Pointer to CDC Class state structure

Return Value

None

DescriptionThis function parses the USB control request to handle different USB CDC special class request. Update

CDCInterfaceInfo with data from USB host, or send data in CDCInterfaceInfo to USB host.

Example

USB_Cl assI nf o_CDC_Devi ce_t Vi r t ual Ser i al _CDC_I nt er f ace =

{

. Conf i g =

{

. Cont r ol I nt er f aceNumber = 0,

. DataI NEndpoi nt =

{

. Addr ess = CDC_TX_EPADDR,

. Si ze = CDC_TXRX_EPSI ZE,

. Banks = 1,

},

. Dat aOUTEndpoi nt =

{

. Address = CDC_RX_EPADDR,

. Si ze = CDC_TXRX_EPSI ZE,

. Banks = 1,

},

. Not i f i cat i onEndpoi nt =

{

. Address = CDC_NOTI FI CATI ON_EPADDR,

. Si ze = CDC_NOTI FI CATI ON_EPSI ZE,

. Banks = 1,

},

},

};CDC_Devi ce_Pr ocessCont r ol Request ( &Vi r t ual Ser i al _CDC_I nt er f ace) ;

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5.1.2. CDC_Device_ConfigureEndpoints

USB CDC device endpoint configuration.

Syntax

bool CDC_Devi ce_Conf i gur eEndpoi nt s( USB_Cl assI nf o_CDC_Devi ce_t * const

CDCI nt er f aceI nf o)

ParametersCDCI nt er f aceI nf o: Poi nt er t o CDC Cl ass st at e st r uct ur e

Return Value

Tr ue: i f conf i gur at i on success

Fal se: i f conf i gurat i on f ai l ure

Description

This functions set data in/out endpoint as bulk type, and set notification endpoint as interrupt type.

Example

bool Conf i gSuccess = t r ue;Conf i gSuccess &= CDC_Devi ce_Conf i gur eEndpoi nts( &Vi r t ual Ser i al _CDC_I nt erf ace) ;

5.1.3. CDC_Device_SendData

USB CDC sends data to USB IN FIFO.

Syntax

ui nt 8_t CDC_Devi ce_SendDat a(USB_Cl assI nf o_CDC_Devi ce_t * const CDCI nter- f aceI nf o,const char * const Buf f er , const ui nt 16_t Lengt h)

Parameters

CDCInterfaceInfo: Pointer to CDC Class state structure

Buffer: Pointer to data buffer

Length: Transmit length

Return Value

Er r or code: def i ni t i on can be f ound i n Endpoi nt St r eam. h

ENDPOI NT_RWSTREAM_NoEr r or

ENDPOI NT_RWSTREAM_Endpoi nt St al l edENDPOI NT_RWSTREAM_Devi ceDi sconnect ed

ENDPOI NT_RWSTREAM_BusSuspended

ENDPOI NT_RWSTREAM_Ti meout

ENDPOI NT_RWSTREAM_I ncompl et eTr ansf er

Description

This function sends data to USB IN FIFO. Transmit data size specified in Length.

Note: Endpoi nt _Cl ear I N( ) must be called to send data to USB host, otherwise, the data will keep in USB device FIFO.

Example

ui nt 32_t r ecv_count ;r ecv_count = uar t _get _dat a( i n_buf f ) ;

i f ( r ecv_count )

{

CDC_Devi ce_SendData( &Vi r t ual Ser i al _CDC_I nt er f ace, ( char *) i n_buf f , r ecv_count ) ;

Endpoi nt _Cl ear I N( ) ;

}

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5.1.4. CDC_Device_SendByte

USB CDC sends one byte to USB IN FIFO.

Syntax

ui nt 8_t CDC_Devi ce_SendByt e(USB_Cl assI nf o_CDC_Devi ce_t * const CDCI nterf aceI nf o,

const ui nt 8_t Dat a)

Parameters

CDCI nt er f aceI nf o: Poi nt er t o CDC Cl ass st at e st r uct ur e

Data: byt e dat a to send

Return Value

Er r or code: def i ni t i on can be f ound i n Endpoi nt St r eam. h

ENDPOI NT_RWSTREAM_NoEr r or

ENDPOI NT_RWSTREAM_Endpoi nt St al l ed

ENDPOI NT_RWSTREAM_Devi ceDi sconnect ed

ENDPOI NT_RWSTREAM_BusSuspended

ENDPOI NT_RWSTREAM_Ti meout

ENDPOI NT_RWSTREAM_I ncompl et eTr ansf er

Description

This function sends one byte to USB IN FIFO.

Note: Endpoi nt _Cl ear I N( ) must be called to send data to USB host, otherwise, the data will keep in USB device FIFO.

Example

CDC_Devi ce_SendByte(&Vi r t ual Ser i al _CDC_I nt erf ace, 0x55) ;Endpoi nt _Cl ear I N( ) ;

5.1.5. CDC_Device_BytesReceived

USB CDC number of bytes received.

Syntax

ui nt 16_t CDC_Devi ce_Byt esRecei ved( USB_Cl assI nf o_CDC_Devi ce_t * const

CDCI nt er f aceI nf o)Parameters

CDCI nt er f aceI nf o: Poi nt er t o CDC Cl ass st at e st r uct ur e

Return Value

Byt es r ecei ved i n USB endpoi nt .

Description

This function check how many bytes received in USB data out endpoint

Example

ui nt 32_t r ecv_count ;r ecv_count = CDC_Devi ce_Byt esRecei ved( &Vi r t ual Ser i al _CDC_I nt erf ace) ;

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5.1.6. CDC_Device_ReceiveByte

USB CDC receive one byte from USB OUT FIFO.

Syntax

i nt 16_t CDC_Devi ce_Recei veByt e(USB_Cl assI nf o_CDC_Devi ce_t * const CDCI nt er f aceI nf o)

Parameters

CDCI nt er f aceI nf o: Poi nt er t o CDC Cl ass st at e st r uct ur e

Return Value

- 1: i f no dat a r ecei ved

Data: one byt e f r om USB data out FI FO.

Description

This function receives one byte from USB data out FIFO. It returns -1 if no data received.

Example

ui nt 32_t out _buf f ;out _buf f = CDC_Devi ce_Recei veByte( &Vi r t ual Seri al _CDC_I nt er f ace) ;

5.1.7. CDC_Device_SendControlL ineStateChange

USB CDC notification.

Syntax

voi d CDC_Devi ce_SendCont r ol Li neStat eChange(USB_Cl assI nf o_CDC_Devi ce_t * const

CDCI nt er f aceI nf o)

Parameters

CDCI nt er f aceI nf o: Poi nt er t o CDC Cl ass st at e st r uct ur e

Return Value

None

Description

This function sends state data to notification endpoint.

Example

CDC_Devi ce_SendCont r ol Li neSt at eChange(CDCI nt er f aceI nf o) ;

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5.2. UART Functions

This section details the functions found in the gUART0.c file (AN758_USB_CDC\src\generated directory). This

file contains the hardware configuration for the SiM3U1xx device.

5.2.1. UART0_enter_default_mode_from_reset

UART0 hardware default configuration.

Syntaxvoi d UART0_ent er_def aul t _mode_f r om_r eset ( voi d)

Parameters

None

Return Value

None

Description

This function set UART0 TX/RX default configuration as 115200 bps, 8-bit data width, 1 bit stop bit, no-parity

ExampleUART0_ent er_def aul t _mode_f r om_r eset ( ) ;

5.2.2. uart_configuration

UART0 configuration setting.

Syntax

voi d uar t _conf i gur at i on( ui nt 32_t baud_r at e, ui nt 8_t st op_bi t s, ui nt 8_t par i t y, ui nt 8_t

dat a_bi t s)

Parameters

baud_r ate: baud rate

st op_bi t s: 0 - 1 st op bi t ; 1 - 1. 5 st op bi t s; 2 - 2 st op bi t s

par i t y: 0 - none; 1 - odd; 2 - even; 3 - mar k; 4 - space

dat a_bi t s: dat a bi t s( 5, 6, 7, 8 or 16)

Return Value

None

DescriptionThis function set UART0 TX/RX baud rate, stop bits, parity and data bits.

Exampleuar t _conf i gur at i on( 115200, 0, 0, 8) ;

5.2.3. uart_get_data

UART0 get data.

Syntax

ui nt 32_t uar t _get _dat a( ui nt 8_t * dat a)

Parameters

dat a: poi nt er t o r ecei ve dat a buf f er

Return ValueThe number of byt es r ecei ved f r om UART

Description

This function gets data from UART FIFO to data buffer and return number of bytes received.

Example

ui nt 32_t r ecv_count ;

stati c ui nt 8_t i n_buf f [ 64] ;r ecv_count = uar t _get _dat a( i n_buf f ) ;

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5.2.4. uart_send_data

UART0 send data.

Syntax

voi d uart _send_dat a(unsi gned char *dat a, unsi gned i nt count )

Parameters

dat a: poi nt er t o send dat a buf f er

count : Number of byt es t o send

Return Value

None

Description

This function send data from data buffer to UART FIFO, transmit data bytes specified in count.

Example

ui nt32_t send_count = 4;

stati c ui nt 8_t out _buf f [ 64] ;uar t _send_dat a( out _buf f , sendcount ) ;

5.2.5. uart_send_byte

UART0 send one byte.

Syntax

voi d uar t _send_byte( ui nt 8_t dat a)

Parameters

data: Byt e to send

Return Value

None

Description

This function sends one byte data to UART FIFO

Example

ui nt 8_t out _byte = 0x55;

uar t _send_byte( out _byte) ;

5.2.6. uart_get_byte

UART0 get one byte.

Syntax

ui nt 8_t uar t _get _byt e( )

Parameters

None

Return Value

Byte recei ved

Description

This function gets one byte data from UART FIFOExample

ui nt 8_t i n_byte;I n_byte = uar t _get _byte( ) ;

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5.3. Application Layer

The application layer for the USB CDC firmware example can be found in the VirtualSerial.c and Descriptors.c

files in theAN758_USB_CDC\src\Virt ualSerialdirectory.

5.3.1. vcp_main

Virtual COM port entry function.

Syntaxvoi d vcp_mai n(voi d)

Parameters

None

Return Value

None

Description

This function initialize USB stack and execute Echo mode or Bridge mode in endless while loop.

Example

ent er _def aul t _mode_f r om_r eset ( ) ;vcp_mai n( ) ;

5.3.2. VCOM_echo

It echo input character to USB virtual COM

Syntax

voi d VCOM_echo( voi d)

Parameters

None

Return Value

None

Description

This function get byte from USB virtual COM port and send back to virtual COM. User will see echo character in

their serial com tool.

ExampleVCOM_echo( ) ;

5.3.3. VCOM_bridge

It transfer data between USB virtual COM port and UART hardware COM port.

Syntax

voi d VCOM_br i dge( voi d)

Parameters

None

Return Value

None

DescriptionThis function acts as USB to UART bridge function.

ExampleVCOM_br i dge( ) ;

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5.3.4. EVENT_USB_Device_ControlRequest

Event handler for control request.

Syntax

voi d EVENT_USB_Devi ce_Cont r ol Request ( voi d)

Parameters

None

Return Value

None

Description

This function is event handler for the library USB Control Request reception event. It handlers USB CDC special

class request from USB host.

Example

i f ( Endpoi nt _I sSETUPRecei ved( ) )

{

ui nt 8_t * Request Header = ( ui nt8_t *) &USB_Cont r ol Request ;

f or ( ui nt8_t Request Header Byt e = 0; Request Header Byt e St at e. Li neEncodi ng. BaudRat eBPS = Endpoi nt _Read_32_LE( ) ;

CDCI nt er f aceI nf o- >St at e. Li neEncodi ng. Char For mat = Endpoi nt _Read_8( ) ;

CDCI nt er f aceI nf o- >St ate. Li neEncodi ng. Par i t yType = Endpoi nt _Read_8( ) ;

CDCI nt er f aceI nf o- >St ate. Li neEncodi ng. DataBi t s = Endpoi nt _Read_8( ) ;

Endpoi nt _Cl ear OUT( ) ;

Endpoi nt _Cl earStatusSt age( ) ;

EVENT_CDC_Devi ce_Li neEncodi ngChanged( CDCI nter f aceI nf o) ;

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5.3.6. EVENT_USB_Device_ConfigurationChanged

Event handler for the library USB Configuration changed event.

Syntax

voi d EVENT_USB_Devi ce_Conf i gur at i onChanged( voi d)

Parameters

None

Return Value

None

Description

This function configures endpoint according USB CDC class interface configuration structure.

ExampleEVENT_USB_Devi ce_Conf i gur at i onChanged( ) ;

5.3.7. CALLBACK_USB_GetDescriptor

Send back descriptor per Get Descriptor request.

Syntax

ui nt 16_t CALLBACK_USB_GetDescr i pt or ( const ui nt 16_t wVal ue,

const ui nt 8_t wI ndex, const voi d** const Descr i pt orAddr ess)

Parameters

None

Return Value

Descr i pt or si ze

Description

When the device receives a Get Descriptor request on the control endpoint, this function is called so that the

descriptor details can be passed back and the appropriate descriptor sent back to the USB host.

Example

const voi d* Descri pt or Poi nt er ;

ui nt 16_t Descri pt or Si ze;

i f ( ( Descr i pt orSi ze = CALLBACK_USB_GetDescr i pt or ( USB_Cont r ol Request . wVal ue,

USB_Cont r ol Request . wI ndex, &Descr i ptorPoi nter ) ) == NO_DESCRI PTOR)

{

return;

}

Endpoi nt _Cl ear SETUP( ) ;

Endpoi nt _Wr i t e_Cont r ol _St r eam_LE( Descr i pt or Poi nt er , Descr i pt or Si ze) ;

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5.3.8. Macros

#def i ne ENDPOI NT_DI R_I N 0x80

#def i ne ENDPOI NT_DI R_OUT 0x00

/ ** Endpoi nt addr ess of t he CDC devi ce- t o- host not i f i cat i on I N endpoi nt . */

#def i ne CDC_NOTI FI CATI ON_EPADDR ( ENDPOI NT_DI R_I N | 1)

/ ** Endpoi nt addr ess of t he CDC devi ce- t o- host data I N endpoi nt . */

#def i ne CDC_TX_EPADDR ( ENDPOI NT_DI R_I N | 2)

/ ** Endpoi nt addr ess of t he CDC host - t o- devi ce dat a OUT endpoi nt . */

#def i ne CDC_RX_EPADDR ( ENDPOI NT_DI R_OUT | 3)

/ * Si ze i n bytes of t he CDC devi ce- t o- host not i f i cat i on I N endpoi nt */

#def i ne CDC_NOTI FI CATI ON_EPSI ZE 16

/ ** Si ze i n byt es of t he CDC data I N and OUT endpoi nt s. */#def i ne CDC_TXRX_EPSI ZE 64

5.3.9. USB CDC Class In terface Structu re

USB_Cl assI nf o_CDC_Devi ce_t Vi r t ual Ser i al _CDC_I nt er f ace =

{

. Conf i g =

{

. Cont r ol I nt er f aceNumber = 0,

. DataI NEndpoi nt =

{

. Addr ess = CDC_TX_EPADDR,

. Si ze = CDC_TXRX_EPSI ZE,

. Banks = 1,

},

. Dat aOUTEndpoi nt =

{. Address = CDC_RX_EPADDR,

. Si ze = CDC_TXRX_EPSI ZE,

. Banks = 1,

},

. Not i f i cat i onEndpoi nt =

{

. Address = CDC_NOTI FI CATI ON_EPADDR,

. Si ze = CDC_NOTI FI CATI ON_EPSI ZE,

. Banks = 1,

},

},};

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5.3.10. USB CDC Descripto rs

Device descriptor structure, this descriptor, located in flash memory, describes the overall device characteristics,

including the supported USB version, control endpoint size and the number of device configurations. The

descriptor is read out by the USB host when the enumeration process begins.

const USB_Descr i ptor_Devi ce_t PROGMEM Devi ceDescr i pt or =

{

. Header = {. Si ze = si zeof ( USB_Descr i pt or_Devi ce_t ) , . Type =

DTYPE_Devi ce},

. USBSpeci f i cat i on = VERSI ON_BCD( 01. 10) ,

. Cl ass = CDC_CSCP_CDCCl ass ,

. SubCl ass = CDC_CSCP_NoSpeci f i cSubcl ass,

. Protocol = CDC_CSCP_NoSpeci f i cProtocol ,

. Endpoi nt 0Si ze = ENDPOI NT_CONTROLEP_DEFAULT_ SI ZE,

. Vendor I D = 0x10C4,

. Product I D = 0xA003,

. Rel easeNumber = VERSI ON_BCD( 00. 01) ,

. Manuf act ur erSt r I ndex = 0x01,

. Product St r I ndex = 0x02,

. Ser i al NumSt r I ndex = USE_I NTERNAL_SERI AL,

. Number Of Conf i gur at i ons = 1

};

Type defines for the device configuration descriptor structure. As the configuration descriptor contains several sub-

descriptors which vary between devices, and which describe the device's usage to the host. Detail definition can be

found in Descriptors.c.

t ypedef st r uct

{

USB_Descr i pt or_Conf i gur at i on_Header_ t Conf i g;

/ / CDC Cont r ol I nt er f ace

USB_Descr i pt or_ I nt er f ace_t CDC_CCI _I nt er f ace;

USB_CDC_Descr i ptor _Funct i onal Header _t CDC_Funct i onal _Header ;

USB_CDC_Descr i ptor _Funct i onal ACM_t CDC_Funct i onal _ACM;

USB_CDC_Descr i pt or_Funct i onal Uni on_t CDC_Funct i onal _Uni on;

USB_Descr i pt or_Endpoi nt _t CDC_Not i f i cat i onEndpoi nt ;

/ / CDC Dat a I nt er f ace

USB_Descr i pt or_I nt er f ace_t CDC_DCI _I nt er f ace;

USB_Descr i ptor _Endpoi nt _t CDC_Dat aOutEndpoi nt ;

USB_Descr i pt or_Endpoi nt_t CDC_DataI nEndpoi nt ;

} USB_Descr i pt or _Conf i gur at i on_t ;

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Example:

const USB_Descr i pt or _Conf i gur at i on_t Conf i gur ati onDescr i pt or ;

String Descriptors

#def i ne STR0LEN 4

st at i c ui nt 8_t const St r i ng0Desc[ STR0LEN] =

{

STR0LEN, DTYPE_St r i ng, 0x09, 0x04

};

#def i ne STR1LEN si zeof ( "SI LI CON LABORATORI ES I NC. " ) *2

st at i c ui nt 8_t const St r i ng1Desc[ STR1LEN] ={. . . }

#def i ne STR2LEN si zeof ( "Si M3U1xx CDC Cl ass" ) *2

st at i c ui nt 8_t const St r i ng2Desc[ STR2LEN] ={. . . }

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5.4.3. USB_Device_SetFullSpeed

Set USB device as full speed.

Syntax

st at i c i nl i ne voi d USB_Devi ce_Set Ful l Speed( voi d)

Parameters

None

Return Value

None

Description

This function set USB device as Full speed.

Example

i f ( USB_Opt i ons & USB_DEVI CE_OPT_LOWSPEED)

{

USB_Devi ce_Set LowSpeed( ) ;

}

el se

{

USB_Devi ce_SetFul l Speed( ) ;}

5.4.4. USB_Device_SetDeviceAddress

Set USB device address.

Syntax

st at i c i nl i ne voi d USB_Devi ce_Set Devi ceAddr ess( const ui nt 8_t Addr ess)

Parameters

Addr ess: USB address

Return Value

None

DescriptionThis function set USB device address assigned from USB host .

Example

ui nt8_t Devi ceAddr ess = ( USB_Contr ol Request . wVal ue & 0x7F) ;USB_Devi ce_Set Devi ceAddr ess( Devi ceAddr ess) ;

5.4.5. USB_Device_IsAddressSet

Check USB device address assigned or not.

Syntax

st at i c i nl i ne bool USB_Devi ce_I sAddr essSet ( voi d)

Parameters

NoneReturn ValueUSB devi ce addr ess

Description

This function USB device address assigned or not.

ExampleUSB_Devi ceSt at e = ( USB_Devi ce_I sAddr essSet ( ) ) ? DEVI CE_STATE_Conf i gur ed :DEVI CE_STATE_Power ed;

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5.4.6. USB_Init

USB hardware initialization.

Syntax

voi d USB_I ni t ( const ui nt 8_t Opt i ons)

Parameters

Opt i ons: USB Devi ce Mode Opt i on

Return Value

None

Description

This function initializes USB hardware. Set full or low speed. Turn on USB 48 MHz oscillators. Enable USB

interrupt. Configure Endpoint to default state. Enable internal pull up resistor to attach USB device.

ExampleUSB_I ni t ( USB_DEVI CE_OPT_FULLSPEED) ;

5.4.7. USB0_IRQHandler

USB interrupt handler.

Syntax

voi d USB0_I RQHandl er( voi d)

Parameters

None

Return Value

None

Description

This function handles all enabled USB device interrupt. Clear interrupt flag. Execute handler function.

ExampleWhen USB interrupt happened, PC will jump to vector table and then jump into this function.

5.4.8. USB0_ep0_handler

Handle endpoint 0 request.Syntax

voi d USB0_ep0_handl er( voi d)

Parameters

None

Return Value

None

Description

This function handles all endpoint 0 request.

Example

i f ( usbEpI nter r upt Mask & SI 32_USB_A_I OI NT_EP0I _MASK)

{

USB0_ep0_handl er ( ) ;

return;}

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5.4.9. USB0_epn_handler

Handle endpoint n request.

Syntax

voi d USB0_epn_handl er( voi d)

Parameters

None

Return Value

None

Description

This function handles all endpoint n request.

Example

i f ( usbEpI nter r upt Mask & ( SI 32_USB_A_I OI NT_I N1I _MASK | SI 32_USB_A_I OI NT_OUT1I _MASK) )

{

Endpoi nt _Sel ect Endpoi nt ( 1) ;

USB0_epn_handl er ( ) ;

}

i f ( usbEpI nter r upt Mask & ( SI 32_USB_A_I OI NT_I N2I _MASK | SI 32_USB_A_I OI NT_OUT2I _MASK) )

{Endpoi nt _Sel ect Endpoi nt ( 2) ;

USB0_epn_handl er ( ) ;}

5.4.10. Endpoint_WaitUnt ilReady

Wait for endpoint ready.

Syntax

ui nt 8_t Endpoi nt _Wai t Unt i l Ready(voi d)

Parameters

None

Return ValueENDPOI NT_READYWAI T_NoEr r or ,

ENDPOI NT_READYWAI T_Endpoi ntSt al l ed,

ENDPOI NT_READYWAI T_Devi ceDi sconnect ed,

ENDPOI NT_READYWAI T_BusSuspended,

ENDPOI NT_READYWAI T_Ti meout

Description

This function will check endpoint ready status. It set 100ms timeout with counting frame number.

Example

i f ( ( Err orCode = Endpoi nt_Wai t Unt i l Ready( ) ) ! = ENDPOI NT_READYWAI T_NoEr r or ) r et ur n Er r orCode;

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5.4.11. Endpoint_ConfigureEndpointTable

Configure endpoint.

Syntax

bool Endpoi nt _Conf i gur eEndpoi nt Tabl e(

const USB_Endpoi nt _Tabl e_t * const Tabl e,

const ui nt 8_t Ent r i es)

Parameters

Tabl e: poi nt er t o endpoi nt t abl e

Ent r i es: no use i n t hi s sof t war e

Return Value

Tr ue: i f conf i gur e successf ul .

Fal se: i f conf i gure f ai l ure.

Description

This function configures endpoint.

Example

i f ( ! ( Endpoi nt _Conf i gur eEndpoi nt Tabl e( &CDCI nt er f aceI nf o- >Conf i g. Dat aI NEndpoi nt , 1) ) ) r et ur n f al se;

5.4.12. Endpoint_Write_Control_Stream_LE

Write stream data to control endpoint

Syntax

ui nt 8_t Endpoi nt _Wr i t e_Cont r ol _St r eam_LE( const voi d* const Buf f er ,

ui nt 16_t Lengt h)

Parameters

Buf f er : poi nt er t o dat a buf f er

Lengt h: Transmi t l engt h

Return Value

ENDPOI NT_RWCSTREAM_NoEr r or

DescriptionThis function writes stream data to control endpoint.

ExampleEndpoi nt _Wr i t e_Cont r ol _St r eam_LE( Descr i pt or Poi nt er , Descr i pt or Si ze) ;

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5.4.13. Endpoint_Write_Stream_LE

Write stream data to correspond endpoint.

Syntax

ui nt 8_t Endpoi nt _Wr i t e_St r eam_LE(const voi d* const Buf f er ,

ui nt 16_t Lengt h,

ui nt 16_t * const Byt esProcessed)

Parameters

Buf f er : poi nt er t o dat a buf f er

Lengt h: Transmi t l engt h

Return Value

ENDPOI NT_RWSTREAM_NoEr r or ,

ENDPOI NT_READYWAI T_Endpoi ntSt al l ed,

ENDPOI NT_READYWAI T_Devi ceDi sconnect ed,

ENDPOI NT_READYWAI T_BusSuspended,

ENDPOI NT_READYWAI T_Ti meout

Description

This function writes stream data to correspond endpoint according usb_ep_selected.

ExampleEndpoi nt _Sel ect Endpoi nt ( CDCI nt er f aceI nf o- >Conf i g. DataI NEndpoi nt . Addr ess) ;

r et ur n Endpoi nt _Wr i t e_St r eam_LE(Buf f er , Lengt h, NULL) ;

5.4.14. Endpoint_ClearIN

Sends an IN packet to the host on the currently selected endpoint.

Syntax

st at i c i nl i ne voi d Endpoi nt _Cl ear I N( voi d)

Parameters

None

Return Value

NoneDescription

This function Sends an IN packet to the host on the currently selected endpoint. It set IPRDYI = 1 to start USB IN

transmits.

Example

CDC_Devi ce_SendData( &Vi r t ual Ser i al _CDC_I nt er f ace, ( char *) i n_buf f , r ecv_count ) ;Endpoi nt _Cl ear I N( ) ;

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5.4.15. Endpoint_ClearOUT

Acknowledges an OUT packet to the host on the currently selected endpoint

Syntax

st at i c i nl i ne voi d Endpoi nt _Cl ear OUT( voi d)

Parameters

None

Return Value

None

Description

This function acknowledges an OUT packet to the host on the currently selected endpoint.

Example

CDCI nt er f aceI nf o- >St at e. Li neEncodi ng. BaudRat eBPS = Endpoi nt _Read_32_LE( ) ;

CDCI nt er f aceI nf o- >St at e. Li neEncodi ng. Char For mat = Endpoi nt _Read_8( ) ;

CDCI nt er f aceI nf o- >St ate. Li neEncodi ng. Par i t yType = Endpoi nt _Read_8( ) ;

CDCI nt er f aceI nf o- >St ate. Li neEncodi ng. DataBi t s = Endpoi nt _Read_8( ) ;

Endpoi nt _Cl ear OUT( ) ;

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5. Select Browse my computer for driver software.

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6. Enter the directory path of the CDC_ACM.inffile (AN758_USB_CDC\src\VirtualSerialdirectory). If the

Include subfoldersoption is checked, entering the main sim3u1xx_USB_CDCdirectory in the

workspace is sufficient.

7. Windows will display a warning. Select Install this dri ver software anyway.

8. When the driver finishes installing, Windows will report the installation results.

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9. Open Device Manager and observe the device. It will now appear under Ports (COM & LPT) with an

assigned COM port number.

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