Atmel AVR4901 Installation and operating instructions

Atmel AVR4901: ASF - USB Vendor Class
Application
Features
• USB 2.0 compliance
- Chapter 9 compliance
- Full Speed (12Mbit/s), High Speed (480Mbit/s) data rates
• Control, Bulk, Isochronous and Interrupt transfer types
• Small stack size frees space for main application
• Remote wakeup support
• USB bus powered support
• Real time (O.S. compliance, interrupt driven)
• Support 8-bit and 32-bit AVR®
1 Introduction
The aim of this document is to provide an easy way to integrate a USB vendor
class application on a new or existing project.
8-/32-bit Atmel
Microcontrollers
Application Note
Rev. 8481A-AVR-01/12

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2 Abbreviations
ASF: AVR Software Framework
CD: Composite Device: a USB device with more than one interface
CDC: Communication Device Class
FS: USB Full Speed
HID: Human Interface Device
HS: USB High Speed
LS: USB Low Speed
MSC: Mass Storage Class
UDC: USB device Controller
UDD: USB device Descriptor
UDI: USB device Interface
USB: Universal Serial Bus
SOF: Start of Frame

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3 Overview
This document includes six sections for all types of requirements when building a
USB device vendor application:
•Vendor class Specification
Provides information to help users with the vendor class specification and when
they need such solution
•Quick start
Describes how to start a ready to use vendor class device example
•Example description
Describes a vendor class device example
•Building a USB device vendor
Describes how to add a USB device vendor interface in a project
•Building a USB vendor class application
Describes how to add a USB vendor class application
•Vendor class in a USB composite device
Describes how to integrate a vendor class interface in a composite device project
For all these sections, it is recommended to know the main modules organization of a
vendor class application:
•User Application
•USB device Interface VENDOR (UDI-VENDOR)
•USB device Controller (UDC)
•USB device Driver (UDD)
For more advanced information concerning the USB stack implementation, please
refer to the Atmel®AVR4900 ASF USB Device stack application note.
Figure 3-1. USB vendor class solution architecture.
NOTE The USB device stack is available in the ASF in the common/services/usb directory.
UDD
UDC UDI – VENDOR
Application
USB Device stack from the ASF

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4 Vendor class specification
The development of a vendor class can be required when the existing class
(http://www.usb.org/developers/defined_class) does not correspond to the user
specification.
Before starting a vendor class specification, check in Table 4-1 that the native USB
classes are not applicable for your USB application.
Table 4-1. Analysis of native classes.
Class PROS. CONS.
HID
•Native driver
•USB Low Speed mode support
•Suitable for controlling or
monitoring an application
•Interrupt endpoint:
olow and full speed
64KB/s
ohigh speed 2.93MB/s
CDC
•High transfer rate
•Simple Host application
(terminal)
•Easy migration for USART based
applications
•Need of *.inf file under Windows®
•Driver not WHQL certified
MSC •Native driver •SCSI protocol adapted only for
mass storage
AUDIO
•Native driver
•Interesting to record or send data
stream
•No handshake data transfer
(isochronous)
When building a vendor class, the main important thing to specify is the transfer
modes used by endpoints.
These can be chosen based on the description given in Table 4-2.
Table 4-2. Endpoint type description.
Endpoint
type
Description Use case
Control
•Low transfer rate
•No need of new endpoint which
can reduce application footprint
•Configuration of the device
Interrupt •Very low transfer
•Frequency guaranteed
•Real time constraints and low
bandwidth transfer
Bulk •High transfer rate
•Transfer guaranteed (ACK)
•Large amount of data transfer
Isochronous •Very High transfer rate
•Transfer not guaranteed
•Streaming application

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5 Quick start
The USB device vendor examples are available in Atmel AVR Studio®5 and ASF.
Hereunder is the procedure to start a USB device vendor class example quickly:
1. Connect the board (for example the Atmel AVR XMEGA®-A3BU Xplained kit)
to the PC using the USB cable.
2. Connect the Atmel debugger (hereafter the JTAGICE3) to program the
device.
Figure 5-1 Board connection.
3. Start AVR Studio 5 and click on “New Example Project from ASF”.
In the New Example Project’s list, select “USB Device Vendor Class Example”
based on the board you are using. The filter list can be used to find the example
quickly.
1
3
2
4

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4. Compile, load and execute.
The project does not require any modification and only needs to be compiled, loaded
and ran. Connect the Atmel debugger supported by the board and press F5.
When running the application for the first time a Found New Hardware Wizard pops
up as showing below, select “No, not this time” and click on “Next”:
5. Load the driver using the inf file.
NOTE Since the USB vendor class is not supported by any native driver, user needs to
provide a proprietary driver or use a third party solution.
For this example, an open source solution “libusb” is used to support this device. An
inf file was generated by the libusb tool. Point to the folder avr4901/driver/ to install
the driver.

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Once the device is correctly installed, lunch the avr_vendor_class_example.exe from
the folder avr4901/tool/. This program will perform a loopback in all endpoints. A
status is displayed to show the correct execution of the application:
5.1 Hardware behavior
During the application execution the hardware (used board) should behave as below:
•A LED is on when USB device is in active mode and is off in SUSPEND mode
•A LED blinks showing that vendor class interface is enabled by the USB Host
•A LED is on when the loopback is running
Figure 5-2. Example with the Atmel XMEGA-A3BU Xplained board.
LED on when
USB is active
LED blinks showing
Vendor interface is
enabled
LED blinks showing
loopback is running

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The user interface description (specific to the board) is defined at the end of ui.c
source file. This file is available within the “Solution Explorer” under
“common/services/usb/class/vendor/device/example/part_number_board/”.
Figure 5-3 ui.c file location.

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6 Example description
6.1 Example content
The ASF provides a USB device vendor class example for various Atmel AVR
products. All these examples share common files and implement the same
application.
The Table 6-1 introduces a summary of the main files included in the USB device
vendor example. These files are associated to the modules described in Figure 3-1.
Table 6-1. USB device VENDOR example files.
Modules Files ASF paths Description
Application main.c
ui.c
conf_usb.h
Examples folder
Main loop.
Set up hardware switches and LEDs to show
operations.
USB device configuration.
udi_vendor.c/h common/services/usb/class/vendor/device/ Vendor class implementation
UDI VENDOR
udi_vendor_desc.c
udi_vendor_conf.h common/services/usb/class/vendor/device/
USB Descriptors for an USB device with
vendor interface (not applicable for USB
composite device)
udc.c/h
udc_desc.h
udi.h
udd.h
common/services/usb/udc/ USB device Core
UDC
usb_protocol.h
usb_atmel.h common/services/usb/ USB Protocol constants
UDD usbb_device.c/h
usbc_device.c/h
usb_device.c/h
avr32/drivers/usbb/
avr32/drivers/usbc/
xmega/drivers/usb/
USB Drivers
6.2 Example behavior
The main.c and ui.c files implement the user interface vendor application. It is
based on three steps:
1. Start USB device:
udc_start();
udc_attach(); // Must be called when the USB cable is plugged
// Cable plugged is detected via VBus events
2. Wait the enable of vendor interface via call-back and enable the loopback
process:
UDI_VENDOR_ENABLE_EXT() // Interface enabled callback
The callback calls:
- udi_vendor_bulk_out_run()// Enable transfer on interrupt OUT endpoint
- udi_vendor_interrupt_out_run()//Enable transfer on interrupt OUT endpoint
- udi_vendor_iso_out_run() //Enable transfer on isochronous OUT endpoint

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3. Perform loopback in all endpoints (Control, Interrupt, Bulk and Isochronous):
// When a OUT data is received, then send this data on IN
void main_vendor_int_out_received(udd_ep_status_t status,
iram_size_t nb_transfered)
{
if (UDD_EP_TRANSFER_OK != status) {
return; // Tranfert aborted, then stop loopback
}
ui_loop_back_state(true);
// Send on IN endpoint the data received on endpoint OUT
udi_vendor_interrupt_in_run(
main_buf_loopback,
nb_transfered,
main_vendor_int_in_received);
}
// When a IN data has been sent, then the OUT transfer is enabled again
void main_vendor_int_in_received(udd_ep_status_t status,
iram_size_t nb_transfered)
{
if (UDD_EP_TRANSFER_OK != status) {
return; // Tranfert aborted, then stop loopback
}
ui_loop_back_state(false);
// Wait a full buffer
udi_vendor_interrupt_out_run(
main_buf_loopback,
sizeof(main_buf_loopback),
main_vendor_int_out_received);
}

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Figure 6-1. Example behavior sequence.
Application
udc
_
start
()
UDC / UDI / UDD
udc
_
attach
()
VBus hi
g
h
UDI_VENDOR_ENABLE_EXT()
Data rece
p
tion
Startup
main_vendor_int_out_received()
Enable loopback process
Reception of OUT data and
send it in IN end
p
oint
Enumeration
Step 1 - Started USB device
Step 2 - Wait the vendor interface enable
Step 3 – Loopback process
udi_vendor_interrupt_in_run()
udi_vendor_interrupt_out_run()
udi_vendor_bulk_out_run()
udi_vendor_iso_out_run()
Data received
by the host
main_vendor_int_in_received()
Sent of IN data and enable
OUT end
p
oint udi_vendor_interrupt_out_run()

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7 Building a USB device vendor
The USB device vendor modules provide a USB vendor interface which can be used
to build a USB vendor class application.
These modules are available in Atmel AVR Studio 5 and can be imported in an AVR
Studio 5 project. This section describes how to add a USB device vendor in a project:
1. Import USB vendor module.
2. Configure personal USB parameters.
3. Call USB routines to run USB device.
7.1 Import USB module
To import the USB vendor module, follow the instructions below:
1. Open or create your project:
2. From project menu, choose “Select Drivers from AVR Software Framework”.
3. Select Services (1), choose USB vendor class (Single Interface Device) (2), and
click on the “Add to selection” button (3).
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2
3

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7.2 USB configuration
All USB stack configurations are stored in the conf_usb.h file in the application
module. These configurations are simple and do not require any specific USB
knowledge.
There is one configuration section for each USB modules: UDC, UDI and UDD.
The UDC configuration possibilities are described in the Atmel AVR4900: ASF – USB
Device Stack application note in the Section 7.1.1: USB device configuration”.
The UDD configuration possibilities are described in the Atmel AVR4900: ASF – USB
Device Stack application note in the Section 7.1.3: USB drivers’ configuration”.
The UDI which is the vendor interface require some configuration described in Table
7-1.
Table 7-1. UDI vendor – configuration.
Define name Type Description
UDI_VENDOR_ENABLE_EXT Call-back function
Call-back function called when vendor interface is enabled
UDI_VENDOR_DISABLE_EXT Call-back function Call-back function called when vendor interface is disabled
UDI_VENDOR_SETUP_OUT_RECEIVED Call-back function Call-back function called when OUT setup request is received
UDI_VENDOR_SETUP_IN_RECEIVED Call-back function Call-back function called when IN setup request is received
UDI_VENDOR_EPS_SIZE_INT_FS
UDI_VENDOR_EPS_SIZE_BULK_FS
UDI_VENDOR_EPS_SIZE_ISO_FS
constant
Interrupt endpoints size for full speed (up to 64)
Bulk endpoints size for full speed (8, 16, 32 or 64)
Isochronous size for full speed (up to 1023)
UDI_VENDOR_EPS_SIZE_INT_HS
UDI_VENDOR_EPS_SIZE_BULK_HS
UDI_VENDOR_EPS_SIZE_ISO_HS
constant
Interrupt endpoints size for full speed (up to 1024)
Bulk endpoints size for full speed (8, 16, 32,..,512)
Isochronous size for full speed (up to 1024)
NOTE It is important to verify the configuration defined in conf_clock.h file, because the
USB hardware requires a specific clock frequency (see comment in conf_clock.h
file).
7.3 USB implementation
This section describes source code to add to run a USB device vendor application.
The implementation is made of three steps:
1. Start USB device.
2. Wait the enable of vendor interface by the Host.
3. Transfer data on USB bus.
7.3.1 USB device control
Only two function calls are needed to start a USB device application, see Figure 7-1.

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Figure 7-1. USB device application sequence.
NOTE In case of a new project, the USB stack requires to enable interrupts and to initialize
the clock and sleepmgr services.
Example:
<conf_usb.h>
#define UDC_VBUS_EVENT(b_vbus_high) \
vbus_event(b_vbus_high)
<main C file>:
main() {
// Authorize interrupts
irq_initialize_vectors();
cpu_irq_enable();
// Initialize the sleep manager service
sleepmgr_init();
// Initialize the clock service
sysclk_init();
// Enable USB Stack device
udc_start();
if (!udc_include_vbus_monitoring()) {
// VBUS monitoring is not available on this product
To start a USB device application
udc_start()
VBus monitoring available
udc_include_vbus_monitoring()
Wait for VBUS power
UDC_VBUS_EVENT()
Enable D+ pull-up resistors
udc_attach()
Bus enumeration
no
no
yes
yes

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// thereby VBUS has to be considered as present
vbus_event (true);
}
}
vbus_event(b_vbus_high) {
if (b_vbus_high) {
// Connect USB device
udc_attach();
}else{
// Disconnect USB device
udc_detach();
}
}
7.3.2 USB interface control
After the device enumeration (detecting and identifying USB devices), the USB Host
starts the device configuration. When the USB vendor class interface is accepted, the
USB host enables this interface and the UDI_VENDOR_ENABLE_EXT() callback
function is called.
When the USB device is unplugged or is reset by USB Host, the USB interface is
disabled and the UDI_VENDOR_DISABLE_EXT() callback function is called.
Example:
<conf_usb.h>
#define UDI_VENDOR_ENABLE_EXT() \
vendor_enable()
#define UDI_VENDOR_DISABLE_EXT() \
vendor_disable()
<user C file>:
vendor_enable() {
// Start an ADC conversion
…
return true;
}
vendor_disable() {
// Stop the ADC conversion
…
}

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7.3.3 USB vendor functions
The USB vendor class functions described in Table 7-2 allow to send or to receive
data.
Table 7-2. UDI vendor class – data functions.
Declaration Description
udi_vendor_interrupt_in_run () Start transfer in an IN interrupt endpoint
udi_vendor_interrupt_out_run () Start transfer in an OUT interrupt endpoint
udi_vendor_bulk_in_run () Start transfer in an IN bulk endpoint
udi_vendor_bulk_out_run () Start transfer in an OUT bulk endpoint
udi_vendor_iso_in_run () Start transfer in an IN isochronous endpoint
udi_vendor_iso_out_run () Start transfer in an OUT isochronous endpoint
7.4 Vendor class and USB Host support
Since the USB vendor class is specified by the user, there is no native support with
any operating system. The user has to build an own driver and host application.
However some solutions exist to help to build a fast solution. The most popular and
free of charge are:
oLibusb: This solution has the advantage to support multi-operating system
platforms (Windows, Linux®, Mac OS®) and offers an open source solution.
Atmel provide an example using this solution available within the Atmel
AVR4901 application note. For further information regarding libusb, please
refer to http://www.libusb.org/
oWinUSB: This solution is provided by and dedicated to Windows platforms
(native form Windows Vista®). WinUSB does not support isochronous transfer
mode. For further information please refer to http://msdn.microsoft.com/en-
us/library/windows/hardware/ff540196(v=vs.85).aspx

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8 Vendor class in a USB composite device
The information required to build a composite device is available in the Atmel
AVR4902 ASF - USB Composite Device application note. A familiarity with this
application note is mandatory.
This section introduced only the specific information required to build a composite
device with a vendor class interface.
8.1 USB configuration
In addition to the USB configuration described in Section 7.2, the following values
must be defined in the conf_usb.h file:
USB_DEVICE_EP_CTRL_SIZE
Endpoint control size.
This must be:
•8, 16, 32, or 64 for full speed device (8 is recommended to save RAM)
•64 for a high speed device
UDI_VENDOR_EP_INTERRUPT_IN
IN interrupt endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_INT_FS is 0).
UDI_VENDOR_EP_INTERRUPT_OUT
OUT interrupt endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_INT_FS is 0).
UDI_VENDOR_EP_BULK_IN
IN bulk endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_BULK_FS is 0).
UDI_VENDOR_EP_ BULK_OUT
OUT bulk endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_BULK_FS is 0).
UDI_VENDOR_EP_ISO_IN
IN isochronous endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_ISO_FS is 0).
UDI_VENDOR_EP_ ISO_OUT
OUT isochronous endpoint number used by the vendor interface (ignored if
UDI_VENDOR_EPS_SIZE_ISO_FS is 0).
UDI_VENDOR_IFACE_NUMBER
Interface number of the vendor interface.
USB_DEVICE_MAX_EP
Total number of endpoints in the application. This must include the number of
endpoints used by vendor interface (0 to 6 depend on UDI_VENDOR_EPS_SIZE_X
defines).

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8.2 USB descriptor
The USB device Descriptor of composite device, defined in conf_usb.h file, must
include a vendor interface:
//! Define structure of composite interfaces descriptor
#define UDI_COMPOSITE_DESC_T \
udi_vendor_desc_t udi_vendor; \
...
//! Fill composite interfaces descriptor for Full Speed
#define UDI_COMPOSITE_DESC_FS \
.udi_vendor = UDI_VENDOR_DESC_FS, \
...
//! Fill composite interfaces descriptor for High Speed
#define UDI_COMPOSITE_DESC_HS \
.udi_vendor = UDI_VENDOR_DESC_HS, \
...
//! Fill Interface APIs corresponding at interfaces descriptor
#define UDI_COMPOSITE_API \
&udi_api_vendor, \
...

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9 Table of contents
Atmel AVR4901: ASF - USB Vendor Class Application ................... 1
Features............................................................................................... 1
1 Introduction ...................................................................................... 1
2 Abbreviations ................................................................................... 2
3 Overview ........................................................................................... 3
4 Vendor class specification.............................................................. 4
5 Quick start ........................................................................................ 5
5.1 Hardware behavior .............................................................................................. 7
6 Example description........................................................................ 9
6.1 Example content.................................................................................................. 9
6.2 Example behavior................................................................................................ 9
7 Building a USB device vendor ...................................................... 12
7.1 Import USB module ........................................................................................... 12
7.2 USB configuration ............................................................................................. 13
7.3 USB implementation.......................................................................................... 13
7.3.1 USB device control.................................................................................................. 13
7.3.2 USB interface control............................................................................................... 15
7.3.3 USB vendor functions.............................................................................................. 16
7.4 Vendor class and USB Host support................................................................. 16
8 Vendor class in a USB composite device.................................... 17
8.1 USB configuration ............................................................................................. 17
8.2 USB descriptor .................................................................................................. 18
9 Table of contents ........................................................................... 19

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