(CDC) ON SiM3U1XX MCUS
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I
M P L E M E N T I N G
U S B C
O M M U N I C A T I O N
D
E V I C E
C
L A S S
( C D C )
O N
S i M 3 U 1
X X
M C U
S
1. Introduction
USB 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.
Serial Device
Host PC USB cable SiM3U1xx
RS232 cable
End device
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 none in the terminal program.
RTS/DTR control is not implemented.
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2. Relevant Documentation
Precision32™ Application Notes are listed on the following website: www.silabs.com/32bit-appnotes .
AN667: Getting Started with the Silicon Labs Precision32™ IDE—provides a description of the IDE features and environment.
AN670: Getting Started with the Silicon Labs Precision32™ AppBuilder —provides 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.
Table 1. Abstract Control Model Requests
Request
SET_LINE_CODING
GET_LINE_CODING
SET_CONTROL_LINE_STATE
Code
20h
21h
22h
Description
Configures baud rate, stop-bits, parity, and numberof-character bits.
Requests current DTE rate, stop-bits, parity, and number-of-character bits.
RS232 signal used to tell the DCE device the DTE device is now present.
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.
bmRequestType
00100001b
bRequest
SET_LINE_CODING
wValue
0
wIndex
interface
wLength
size of structure
Data
line coding structure
Table 2 defines the line coding properties.
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Offset
0
4
5
Field
dwDTERate bCharFormat bParityType
Table 2. Line Coding Format
Size
4
1
Value
Number
Number
1
1
Number
Number
Description
Data terminal rate, in bits per second.
0: 1 Stop bit
1: 1.5 Stop bits
2: 2 Stop bits
Parity:
0:None
1: Odd
2: Even
3: Mark
4: Space
Data bits (5, 6, 7, 8 or 16).
6 bDataBits
3.1.2. Get Line Coding
properties.
bmRequestType
10100001b
bRequest
GET_LINE_CODING
wValue
0
wIndex
interface
wLength
size of structure
3.1.3. Set Control Line State
This request generates RS-232/V.24 style control signals. Table 3 defines control signal bitmap.
Data
line coding structure
bmRequestType
00100001b
bRequest
SET_LINE_CON-
TROL_STATE
wValue
control signal bitmap
wIndex
interface
wLength
0
Data
none
Table 3. Control Signal Bitmap
Bit Position Description
15:2
1
0
Reserved (Reset to zero).
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.
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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3.2. Class Notifications
Table 4 shows the class notifications supported by the Abstract Control Model.
Table 4. Abstract Control Model Notifications
Notification
SERIAL_STATE
Code
20h
Description
Returns the current state of the carrier detects, DSR, break, and ring signal.
3.2.1. Serial State
This notification sends an asynchronous message containing the current UART status.
bmRequestType
10100001b
bRequest
SERIAL_STATE
wValue
0
wIndex
interface
wLength
2
Data
UART state bitmap
The data field for this notification is a bitmapped value that contains the current state of detects transmission carrier, break, ring signal, and device overrun error. These signals are typically found on a UART and are used for communication status reporting. A state is considered enabled if its respective bit is set to 1.
Note: The firmware example included with this application does not currently support state change.
Table 5. UART State Bitmap
Bit Position
15:7
6
5
2
1
4
3
0
Field Description
Reserved (future use).
bOverRun Received data has been discarded due to overrun in the device.
bParity A parity error occurred.
bFraming A framing error occurred.
bRingSignal State of ring signal detection of the device.
bBreak State of break detection mechanism of the device.
bTxCarrier State of transmission carrier. This signal corresponds to V.24 signal 106 and
RS232 signal DSR.
bRxCarrier State of receiver carrier detection mechanism of device. This signal corresponds to V.24 signal 109 and RS232 signal DCD.
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3.3. Endpoint Configuration
Table 6 illustrates the endpoint configuration for the Abstract Control Model.
Table 6. UART State Bitmap
Endpoint
EP0
EP1
EP2
EP3
Direction
In/Out
In
In
Out
Type
Control
Interrupt
Bulk
Bulk
Max Packet
Size
Description
64
16
Standard requests, class requests.
State notification from device to host.
64
64
Data transfer from device to host.
Data transfer from host to device.
Figure 2 shows a standard CDC communication flow.
Figure 2. USB CDC Communication Flow
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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 PCside application layer code.
4.1. File Organization
The files included in the USB CDC example are as follows:
generated—directory containing SiM3U1xx hardware initialization files
VirtualSerial—directory containing the virtual COM demo files
CDC_ACM.inf
—
USB CDC INF file
Descriptors.c
—
Virtual COM USB descriptors
LUFAConfig.h
—
Project configuration
VirtualSerial.c
— primary application file
LUFA—SiM3L1xx USB stack firmware
Common
— common header files
Drivers
—
USB driver files
Misc
— miscellaneous files
USB
—
USB stack files
Class
—
USB class files
Device
—
USB 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
Host
—
USB host class files, not implemented by the SiM3U1xx
Common
— common driver files
Core
—
USB Chapter 9 handler files
SiM3U
—
SiM3U1xx 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.h
—
USB 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, HID
Class, 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\Drivers\USB\Class\Device directory). This file implements the USB CDC device class.
5.1.1. CDC_Device_Process_ControlRequest
Handle USB CDC special class request.
Syntax
void CDC_Device_ProcessControlRequest(USB_ClassInfo_CDC_Device_t* const
CDCInterfaceInfo)
Parameters
CDCInterfaceInfo
: Pointer to CDC Class state structure
Return Value
None
Description
This 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_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface =
{
.Config =
{
.ControlInterfaceNumber = 0,
.DataINEndpoint =
{
.Address = CDC_TX_EPADDR,
.Size = CDC_TXRX_EPSIZE,
.Banks = 1,
},
.DataOUTEndpoint =
{
.Address = CDC_RX_EPADDR,
.Size = CDC_TXRX_EPSIZE,
.Banks = 1,
},
.NotificationEndpoint =
{
.Address = CDC_NOTIFICATION_EPADDR,
.Size = CDC_NOTIFICATION_EPSIZE,
.Banks = 1,
},
},
};
CDC_Device_ProcessControlRequest(&VirtualSerial_CDC_Interface);
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5.1.2. CDC_Device_ConfigureEndpoints
U
SB CDC device endpoint configuration.
Syntax
bool CDC_Device_ConfigureEndpoints(USB_ClassInfo_CDC_Device_t* const
CDCInterfaceInfo)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Return Value
True: if configuration success
False: if configuration failure
Description
This functions set data in/out endpoint as bulk type, and set notification endpoint as interrupt type.
Example
bool ConfigSuccess = true;
ConfigSuccess &= CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface);
5.1.3. CDC_Device_SendData
USB CDC sends data to USB IN FIFO.
Syntax
uint8_t CDC_Device_SendData(USB_ClassInfo_CDC_Device_t* const CDCInter-faceInfo, const char* const Buffer,const uint16_t Length)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Buffer: Pointer to data buffer
Length: Transmit length
Return Value
Error code: definition can be found in EndpointStream.h
ENDPOINT_RWSTREAM_NoError
ENDPOINT_RWSTREAM_EndpointStalled
ENDPOINT_RWSTREAM_DeviceDisconnected
ENDPOINT_RWSTREAM_BusSuspended
ENDPOINT_RWSTREAM_Timeout
ENDPOINT_RWSTREAM_IncompleteTransfer
Description
This function sends data to USB IN FIFO. Transmit data size specified in Length.
Note: Endpoint_ClearIN() must be called to send data to USB host, otherwise, the data will keep in USB device FIFO.
Example
uint32_t recv_count; recv_count = uart_get_data(in_buff); if(recv_count)
{
CDC_Device_SendData(&VirtualSerial_CDC_Interface, (char *)in_buff, recv_count);
Endpoint_ClearIN();
}
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5.1.4. CDC_Device_SendByte
USB CDC sends one byte to USB IN FIFO.
Syntax
uint8_t CDC_Device_SendByte(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo, const uint8_t Data)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Data: byte data to send
Return Value
Error code: definition can be found in EndpointStream.h
ENDPOINT_RWSTREAM_NoError
ENDPOINT_RWSTREAM_EndpointStalled
ENDPOINT_RWSTREAM_DeviceDisconnected
ENDPOINT_RWSTREAM_BusSuspended
ENDPOINT_RWSTREAM_Timeout
ENDPOINT_RWSTREAM_IncompleteTransfer
Description
This function sends one byte to USB IN FIFO.
Note: Endpoint_ClearIN()must be called to send data to USB host, otherwise, the data will keep in USB device FIFO.
Example
CDC_Device_SendByte(&VirtualSerial_CDC_Interface,0x55);
Endpoint_ClearIN();
5.1.5. CDC_Device_BytesReceived
USB CDC number of bytes received.
Syntax
uint16_t CDC_Device_BytesReceived(USB_ClassInfo_CDC_Device_t* const
CDCInterfaceInfo)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Return Value
Bytes received in USB endpoint.
Description
This function check how many bytes received in USB data out endpoint
Example
uint32_t recv_count; recv_count = CDC_Device_BytesReceived(&VirtualSerial_CDC_Interface);
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5.1.6. CDC_Device_ReceiveByte
USB CDC receive one byte from USB OUT FIFO.
Syntax
int16_t CDC_Device_ReceiveByte(USB_ClassInfo_CDC_Device_t* const CDCInterfaceInfo)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Return Value
-1: if no data received
Data: one byte from USB data out FIFO.
Description
This function receives one byte from USB data out FIFO. It returns -1 if no data received.
Example
uint32_t out_buff; out_buff = CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface);
5.1.7. CDC_Device_SendControlLineStateChange
USB CDC notification.
Syntax
void CDC_Device_SendControlLineStateChange(USB_ClassInfo_CDC_Device_t* const
CDCInterfaceInfo)
Parameters
CDCInterfaceInfo: Pointer to CDC Class state structure
Return Value
None
Description
This function sends state data to notification endpoint.
Example
CDC_Device_SendControlLineStateChange(CDCInterfaceInfo);
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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.
Syntax
void UART0_enter_default_mode_from_reset(void)
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
Example
UART0_enter_default_mode_from_reset();
5.2.2. uart_configuration
UART0 configuration setting.
Syntax
void uart_configuration(uint32_t baud_rate,uint8_t stop_bits,uint8_t parity,uint8_t data_bits)
Parameters
baud_rate: baud rate stop_bits: 0 - 1 stop bit; 1 - 1.5 stop bits; 2 - 2 stop bits parity: 0 - none; 1 - odd; 2 - even; 3 - mark; 4 - space data_bits: data bits(5,6,7,8 or 16)
Return Value
None
Description
This function set UART0 TX/RX baud rate, stop bits, parity and data bits.
Example
uart_configuration(115200,0,0,8);
5.2.3. uart_get_data
UART0 get data.
Syntax
uint32_t uart_get_data(uint8_t * data)
Parameters
data: pointer to receive data buffer
Return Value
The number of bytes received from UART
Description
This function gets data from UART FIFO to data buffer and return number of bytes received.
Example
uint32_t recv_count; static uint8_t in_buff[64]; recv_count = uart_get_data(in_buff);
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5.2.4. uart_send_data
UART0 send data.
Syntax
void uart_send_data(unsigned char *data, unsigned int count)
Parameters
data: pointer to send data buffer count: Number of bytes to send
Return Value
None
Description
This function send data from data buffer to UART FIFO, transmit data bytes specified in count.
Example
uint32_t send_count = 4; static uint8_t out_buff[64]; uart_send_data(out_buff,sendcount);
5.2.5. uart_send_byte
UART0 send one byte.
Syntax
void uart_send_byte(uint8_t data)
Parameters
data: Byte to send
Return Value
None
Description
This function sends one byte data to UART FIFO
Example
uint8_t out_byte = 0x55; uart_send_byte(out_byte);
5.2.6. uart_get_byte
UART0 get one byte.
Syntax
uint8_t uart_get_byte()
Parameters
None
Return Value
Byte received
Description
This function gets one byte data from UART FIFO
Example
uint8_t in_byte;
In_byte = uart_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 the AN758_USB_CDC\src\VirtualSerial directory.
5.3.1. vcp_main
Virtual COM port entry function.
Syntax
void vcp_main(void)
Parameters
None
Return Value
None
Description
This function initialize USB stack and execute Echo mode or Bridge mode in endless while loop.
Example
enter_default_mode_from_reset(); vcp_main();
5.3.2. VCOM_echo
It echo input character to USB virtual COM
Syntax
void VCOM_echo(void)
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.
Example
VCOM_echo();
5.3.3. VCOM_bridge
It transfer data between USB virtual COM port and UART hardware COM port.
Syntax
void VCOM_bridge(void)
Parameters
None
Return Value
None
Description
This function acts as USB to UART bridge function.
Example
VCOM_bridge();
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5.3.4. EVENT_USB_Device_ControlRequest
Event handler for control request.
Syntax
void EVENT_USB_Device_ControlRequest(void)
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
if(Endpoint_IsSETUPReceived())
{ uint8_t* RequestHeader = (uint8_t*)&USB_ControlRequest; for (uint8_t RequestHeaderByte = 0; RequestHeaderByte < sizeof(USB_Request_Header_t); RequestHeaderByte++)
*(RequestHeader++) = Endpoint_Read_8();
}
EVENT_USB_Device_ControlRequest();
5.3.5. EVENT_CDC_Device_LineEncodingChanged
Event handler for the CDC Class driver Line Encoding Changed event.
Syntax
void EVENT_CDC_Device_LineEncodingChanged(USB_ClassInfo_CDC_Device_t* const
CDCInterfaceInfo)
Parameters
CDCInterfaceInfo:Pointer to the CDC class interface configuration structure
Return Value
None
Description
This function change UART configuration according CDC class interface configuration.
Example
CDCInterfaceInfo->State.LineEncoding.BaudRateBPS = Endpoint_Read_32_LE();
CDCInterfaceInfo->State.LineEncoding.CharFormat = Endpoint_Read_8();
CDCInterfaceInfo->State.LineEncoding.ParityType = Endpoint_Read_8();
CDCInterfaceInfo->State.LineEncoding.DataBits = Endpoint_Read_8();
Endpoint_ClearOUT();
Endpoint_ClearStatusStage();
EVENT_CDC_Device_LineEncodingChanged(CDCInterfaceInfo);
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5.3.6. EVENT_USB_Device_ConfigurationChanged
Event handler for the library USB Configuration changed event.
Syntax
void EVENT_USB_Device_ConfigurationChanged(void)
Parameters
None
Return Value
None
Description
This function configures endpoint according USB CDC class interface configuration structure.
Example
EVENT_USB_Device_ConfigurationChanged();
5.3.7. CALLBACK_USB_GetDescriptor
Send back descriptor per Get Descriptor request.
Syntax
uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
const uint8_t wIndex,
const void** const DescriptorAddress)
Parameters
None
Return Value
Descriptor size
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 void* DescriptorPointer; uint16_t DescriptorSize; if ((DescriptorSize = CALLBACK_USB_GetDescriptor(USB_ControlRequest.wValue,
USB_ControlRequest.wIndex,&DescriptorPointer )) == NO_DESCRIPTOR)
{ return;
}
Endpoint_ClearSETUP();
Endpoint_Write_Control_Stream_LE(DescriptorPointer, DescriptorSize);
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5.3.8. Macros
#define ENDPOINT_DIR_IN 0x80
#define ENDPOINT_DIR_OUT 0x00
/** Endpoint address of the CDC device-to-host notification IN endpoint. */
#define CDC_NOTIFICATION_EPADDR (ENDPOINT_DIR_IN | 1)
/** Endpoint address of the CDC device-to-host data IN endpoint. */
#define CDC_TX_EPADDR (ENDPOINT_DIR_IN | 2)
/** Endpoint address of the CDC host-to-device data OUT endpoint. */
#define CDC_RX_EPADDR (ENDPOINT_DIR_OUT | 3)
/* Size in bytes of the CDC device-to-host notification IN endpoint*/
#define CDC_NOTIFICATION_EPSIZE 16
/** Size in bytes of the CDC data IN and OUT endpoints. */
#define CDC_TXRX_EPSIZE 64
5.3.9. USB CDC Class Interface Structure
USB_ClassInfo_CDC_Device_t VirtualSerial_CDC_Interface =
{
.Config =
{
.ControlInterfaceNumber = 0,
.DataINEndpoint =
{
.Address = CDC_TX_EPADDR,
.Size = CDC_TXRX_EPSIZE,
.Banks = 1,
},
.DataOUTEndpoint =
{
.Address = CDC_RX_EPADDR,
.Size = CDC_TXRX_EPSIZE,
.Banks = 1,
},
.NotificationEndpoint =
{
.Address = CDC_NOTIFICATION_EPADDR,
.Size = CDC_NOTIFICATION_EPSIZE,
.Banks = 1,
},
},
};
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5.3.10. USB CDC Descriptors
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_Descriptor_Device_t PROGMEM DeviceDescriptor =
{
.Header = {.Size = sizeof(USB_Descriptor_Device_t), .Type =
DTYPE_Device},
.USBSpecification = VERSION_BCD(01.10),
.Class = CDC_CSCP_CDCClass,
.SubClass = CDC_CSCP_NoSpecificSubclass,
.Protocol = CDC_CSCP_NoSpecificProtocol,
.Endpoint0Size = ENDPOINT_CONTROLEP_DEFAULT_SIZE,
.VendorID = 0x10C4,
.ProductID = 0xA003,
.ReleaseNumber = VERSION_BCD(00.01),
.ManufacturerStrIndex = 0x01,
.ProductStrIndex = 0x02,
.SerialNumStrIndex = USE_INTERNAL_SERIAL,
.NumberOfConfigurations = 1
};
Type defines for the device configuration descriptor structure. As the configuration descriptor contains several subdescriptors which vary between devices, and which describe the device's usage to the host. Detail definition can be found in Descriptors.c. typedef struct
{
USB_Descriptor_Configuration_Header_t Config;
// CDC Control Interface
USB_Descriptor_Interface_t CDC_CCI_Interface;
USB_CDC_Descriptor_FunctionalHeader_t CDC_Functional_Header;
USB_CDC_Descriptor_FunctionalACM_t CDC_Functional_ACM;
USB_CDC_Descriptor_FunctionalUnion_t CDC_Functional_Union;
USB_Descriptor_Endpoint_t CDC_NotificationEndpoint;
// CDC Data Interface
USB_Descriptor_Interface_t CDC_DCI_Interface;
USB_Descriptor_Endpoint_t CDC_DataOutEndpoint;
USB_Descriptor_Endpoint_t CDC_DataInEndpoint;
} USB_Descriptor_Configuration_t;
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Example:
const USB_Descriptor_Configuration_t ConfigurationDescriptor;
String Descriptors
#define STR0LEN 4 static uint8_t const String0Desc[STR0LEN] =
{
STR0LEN, DTYPE_String, 0x09, 0x04
};
#define STR1LEN sizeof("SILICON LABORATORIES INC.")*2 static uint8_t const String1Desc[STR1LEN] ={...}
#define STR2LEN sizeof("SiM3U1xx CDC Class")*2 static uint8_t const String2Desc[STR2LEN] ={...}
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5.4. USB Low-Level Functions
The USB hardware access layer functions are in the AN758_USB_CDC\src\LUFA\Drivers\USB\Core\SIM3U directory.
5.4.1. USB_Device_GetFrameNumber
Returns the current USB frame number.
Syntax
static inline uint16_t USB_Device_GetFrameNumber(void)
Parameters
None
Return Value
Current USB frame number from the USB controller
Description
This function returns the current USB frame number, when in device mode. Every millisecond the USB bus is active.
Example
uint16_t PreviousFrameNumber = USB_Device_GetFrameNumber();
5.4.2. USB_Device_SetLowSpeed
Set USB device as low speed.
Syntax
static inline void USB_Device_SetLowSpeed(void)
Parameters
None
Return Value
None
Description
This function set USB device as low speed.
Example
if (USB_Options & USB_DEVICE_OPT_LOWSPEED)
{
USB_Device_SetLowSpeed();
} else
{
USB_Device_SetFullSpeed();
}
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5.4.3. USB_Device_SetFullSpeed
Set USB device as full speed.
Syntax
static inline void USB_Device_SetFullSpeed(void)
Parameters
None
Return Value
None
Description
This function set USB device as Full speed.
Example
if (USB_Options & USB_DEVICE_OPT_LOWSPEED)
{
USB_Device_SetLowSpeed();
} else
{
USB_Device_SetFullSpeed();
}
5.4.4. USB_Device_SetDeviceAddress
Set USB device address.
Syntax
static inline void USB_Device_SetDeviceAddress(const uint8_t Address)
Parameters
Address: USB address
Return Value
None
Description
This function set USB device address assigned from USB host .
Example
uint8_t DeviceAddress = (USB_ControlRequest.wValue & 0x7F);
USB_Device_SetDeviceAddress(DeviceAddress);
5.4.5. USB_Device_IsAddressSet
Check USB device address assigned or not.
Syntax
static inline bool USB_Device_IsAddressSet(void)
Parameters
None
Return Value
USB device address
Description
This function USB device address assigned or not.
Example
USB_DeviceState = (USB_Device_IsAddressSet()) ? DEVICE_STATE_Configured :
DEVICE_STATE_Powered;
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5.4.6. USB_Init
USB hardware initialization.
Syntax
void USB_Init(const uint8_t Options)
Parameters
Options: USB Device Mode Option
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.
Example
USB_Init(USB_DEVICE_OPT_FULLSPEED);
5.4.7. USB0_IRQHandler
USB interrupt handler.
Syntax
void USB0_IRQHandler(void)
Parameters
None
Return Value
None
Description
This function handles all enabled USB device interrupt. Clear interrupt flag. Execute handler function.
Example
When 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
void USB0_ep0_handler(void)
Parameters
None
Return Value
None
Description
This function handles all endpoint 0 request.
Example
if (usbEpInterruptMask & SI32_USB_A_IOINT_EP0I_MASK)
{
USB0_ep0_handler(); return;
}
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5.4.9. USB0_epn_handler
Handle endpoint n request.
Syntax
void USB0_epn_handler(void)
Parameters
None
Return Value
None
Description
This function handles all endpoint n request.
Example
if (usbEpInterruptMask & (SI32_USB_A_IOINT_IN1I_MASK | SI32_USB_A_IOINT_OUT1I_MASK))
{
} if (usbEpInterruptMask & (SI32_USB_A_IOINT_IN2I_MASK | SI32_USB_A_IOINT_OUT2I_MASK))
{
Endpoint_SelectEndpoint(1);
USB0_epn_handler();
Endpoint_SelectEndpoint(2);
USB0_epn_handler();
}
5.4.10. Endpoint_WaitUntilReady
Wait for endpoint ready.
Syntax
uint8_t Endpoint_WaitUntilReady(void)
Parameters
None
Return Value
ENDPOINT_READYWAIT_NoError,
ENDPOINT_READYWAIT_EndpointStalled,
ENDPOINT_READYWAIT_DeviceDisconnected,
ENDPOINT_READYWAIT_BusSuspended,
ENDPOINT_READYWAIT_Timeout
Description
This function will check endpoint ready status. It set 100ms timeout with counting frame number.
Example
if ((ErrorCode = Endpoint_WaitUntilReady()) != ENDPOINT_READYWAIT_NoError)
return ErrorCode;
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5.4.11. Endpoint_ConfigureEndpointTable
Configure endpoint.
Syntax
bool Endpoint_ConfigureEndpointTable( const USB_Endpoint_Table_t* const Table,
const uint8_t Entries)
Parameters
Table: pointer to endpoint table
Entries: no use in this software
Return Value
True: if configure successful.
False: if configure failure.
Description
This function configures endpoint.
Example
if (!(Endpoint_ConfigureEndpointTable(&CDCInterfaceInfo->Config.DataINEndpoint, 1)))
return false;
5.4.12. Endpoint_Write_Control_Stream_LE
Write stream data to control endpoint
Syntax
uint8_t Endpoint_Write_Control_Stream_LE(const void* const Buffer, uint16_t Length)
Parameters
Buffer: pointer to data buffer
Length: Transmit length
Return Value
ENDPOINT_RWCSTREAM_NoError
Description
This function writes stream data to control endpoint.
Example
Endpoint_Write_Control_Stream_LE(DescriptorPointer, DescriptorSize);
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5.4.13. Endpoint_Write_Stream_LE
Write stream data to correspond endpoint.
Syntax
uint8_t Endpoint_Write_Stream_LE(const void* const Buffer, uint16_t Length, uint16_t* const BytesProcessed)
Parameters
Buffer: pointer to data buffer
Length: Transmit length
Return Value
ENDPOINT_RWSTREAM_NoError,
ENDPOINT_READYWAIT_EndpointStalled,
ENDPOINT_READYWAIT_DeviceDisconnected,
ENDPOINT_READYWAIT_BusSuspended,
ENDPOINT_READYWAIT_Timeout
Description
This function writes stream data to correspond endpoint according usb_ep_selected.
Example
Endpoint_SelectEndpoint(CDCInterfaceInfo->Config.DataINEndpoint.Address); return Endpoint_Write_Stream_LE(Buffer, Length, NULL);
5.4.14. Endpoint_ClearIN
Sends an IN packet to the host on the currently selected endpoint.
Syntax
static inline void Endpoint_ClearIN(void)
Parameters
None
Return Value
None
Description
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_Device_SendData(&VirtualSerial_CDC_Interface, (char *)in_buff, recv_count);
Endpoint_ClearIN();
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5.4.15. Endpoint_ClearOUT
Acknowledges an OUT packet to the host on the currently selected endpoint
Syntax
static inline void Endpoint_ClearOUT(void)
Parameters
None
Return Value
None
Description
This function acknowledges an OUT packet to the host on the currently selected endpoint.
Example
CDCInterfaceInfo->State.LineEncoding.BaudRateBPS = Endpoint_Read_32_LE();
CDCInterfaceInfo->State.LineEncoding.CharFormat = Endpoint_Read_8();
CDCInterfaceInfo->State.LineEncoding.ParityType = Endpoint_Read_8();
CDCInterfaceInfo->State.LineEncoding.DataBits = Endpoint_Read_8();
Endpoint_ClearOUT();
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6. CDC Driver
The CDC class is implemented in all releases of Windows, and the operating system needs an INF file for the CDC driver. This INF file contains the Vendor ID and Product ID. If the VID/PID of the USB devices matches the INF file,
Windows will load the driver described in the file. The CDC_ACM INF file can be found in the
AN758_USB_CDC\src\VirtualSerial directory.
6.1. Installing the Driver
To install the driver on Windows 7:
1. Build the project and download firmware to the SiM3U1xx MCU card.
2. Connect the USB cable between the Device USB connector (J13) and the PC.
3. Open Device Manager. The device will appear under Other devices as the SiM3U1xx CDC Class device.
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4. Right-click on the SiM3U1xx CDC Class device and select Update Driver Software.
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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.inf file (AN758_USB_CDC\src\VirtualSerial directory). If the
Include subfolders option is checked, entering the main sim3u1xx_USB_CDC directory in the workspace is sufficient.
7. Windows will display a warning. Select Install this driver software anyway.
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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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Simplicity Studio
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Disclaimer
Silicon Labs intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Labs products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and "Typical" parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Labs reserves the right to make changes without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included information. Silicon Labs shall have no liability for the consequences of use of the information supplied herein. This document does not imply or express copyright licenses granted hereunder to design or fabricate any integrated circuits. The products are not designed or authorized to be used within any Life Support System without the specific written consent of
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