Atmel Software Framework

Quick start guide for USB device generic module (UDI generic)

This is the quick start guide for the USB device generic module (UDI generic) with step-by-step instructions on how to configure and use the modules in a selection of use cases.

The use cases contain several code fragments. The code fragments in the steps for setup can be copied into a custom initialization function, while the steps for usage can be copied into, e.g., the main application function.

Also, you can refer to application note AVR4905: ASF - USB Device HID Generic Application.

Basic use case

In this basic use case, the "USB HID Generic (Single Interface Device)" module is used. The "USB HID Generic (Composite Device)" module usage is described in Advanced use cases.

Setup steps

Prerequisites

This module is based on USB device stack full interrupt driven, and supporting Sleep manager sleepmgr. For AVR and SAM3/4 devices the Clock Management clock services is supported. For SAMD devices the asfdoc_sam0_system_clock_group clock driver is supported.

The following procedure must be executed to setup the project correctly:

  • Specify the clock configuration:
    • XMEGA USB devices need 48MHz clock input.
      XMEGA USB devices need CPU frequency higher than 12MHz.
      You can use either an internal RC48MHz auto calibrated by Start of Frames or an external OSC.
    • UC3 and SAM3/4 devices without USB high speed support need 48MHz clock input.
      You must use a PLL and an external OSC.
    • UC3 and SAM3/4 devices with USB high speed support need 12MHz clock input.
      You must use an external OSC.
    • UC3 devices with USBC hardware need CPU frequency higher than 25MHz.
    • SAMD devices without USB high speed support need 48MHz clock input.
      You should use DFLL with USBCRM.
  • In conf_board.h, the define CONF_BOARD_USB_PORT must be added to enable USB lines. (Not mandatory for all boards)
  • Enable interrupts
  • Initialize the clock service

The usage of Sleep manager sleepmgr service is optional, but recommended to reduce power consumption:

  • Initialize the sleep manager service
  • Activate sleep mode when the application is in IDLE state

conf_clock.h examples with USB support.

for AVR and SAM3/4 devices, add to the initialization code:

For SAMD devices, add to the initialization code:

system_init();
sleepmgr_init(); // Optional

Add to the main IDLE loop:

sleepmgr_enter_sleep(); // Optional

Example code

Content of conf_usb.h:

#define USB_DEVICE_VENDOR_ID 0x03EB
#define USB_DEVICE_PRODUCT_ID 0xXXXX
#define USB_DEVICE_MAJOR_VERSION 1
#define USB_DEVICE_MINOR_VERSION 0
#define USB_DEVICE_POWER 100
#define USB_DEVICE_ATTR USB_CONFIG_ATTR_BUS_POWERED

Add to application C-file:

void usb_init(void)
{
}

Workflow

  1. Ensure that conf_usb.h is available and contains the following configuration which is the main USB device configuration:
// Vendor ID provided by USB org (ATMEL 0x03EB)
#define USB_DEVICE_VENDOR_ID 0x03EB // Type Word
// Product ID (Atmel PID referenced in usb_atmel.h)
#define USB_DEVICE_PRODUCT_ID 0xXXXX // Type Word
// Major version of the device
#define USB_DEVICE_MAJOR_VERSION 1 // Type Byte
// Minor version of the device
#define USB_DEVICE_MINOR_VERSION 0 // Type Byte
// Maximum device power (mA)
#define USB_DEVICE_POWER 100 // Type 9-bits
// USB attributes to enable features
#define USB_DEVICE_ATTR USB_CONFIG_ATTR_BUS_POWERED // Flags
  1. Call the USB device stack start function to enable stack and start USB:
    • Note
      In case of USB dual roles (Device and Host) managed through USB OTG connector (USB ID pin), the call of udc_start() must be removed and replaced by uhc_start(). SeRefer to "AVR4950 section 6.1 Dual roles" for further information about dual roles.

Usage steps

Example code

Content of conf_usb.h:

#define UDI_HID_GENERIC_ENABLE_EXT() my_callback_generic_enable()
extern bool my_callback_generic_enable(void);
#define UDI_HID_GENERIC_DISABLE_EXT() my_callback_generic_disable()
extern void my_callback_generic_disable(void);
#define UDI_HID_GENERIC_REPORT_OUT(ptr) my_callback_generic_report_out(ptr)
extern void my_callback_generic_report_out(uint8_t *report);
#define UDI_HID_GENERIC_SET_FEATURE(f) my_callback_generic_set_feature(f)
extern void my_callback_generic_set_feature(uint8_t *report_feature);
#define UDI_HID_REPORT_IN_SIZE 64
#define UDI_HID_REPORT_OUT_SIZE 64
#define UDI_HID_REPORT_FEATURE_SIZE 4
#define UDI_HID_GENERIC_EP_SIZE 64
#include "udi_hid_generic_conf.h" // At the end of conf_usb.h file

Add to application C-file:

static bool my_flag_autorize_generic_events = false;
bool my_callback_generic_enable(void)
{
my_flag_autorize_generic_events = true;
return true;
}
void my_callback_generic_disable(void)
{
my_flag_autorize_generic_events = false;
}
void my_button_press_event(void)
{
if (!my_flag_autorize_generic_events) {
return;
}
uint8_t report[] = {0x00,0x01,0x02...};
}
void my_callback_generic_report_out(uint8_t *report)
{
if ((report[0] == MY_VALUE_0)
(report[1] == MY_VALUE_1)) {
// The report is correct
}
}
void my_callback_generic_set_feature(uint8_t *report_feature)
{
if ((report_feature[0] == MY_VALUE_0)
(report_feature[1] == MY_VALUE_1)) {
// The report feature is correct
}
}

Workflow

  1. Ensure that conf_usb.h is available and contains the following configuration which is the USB device generic configuration:
    • #define UDI_HID_GENERIC_ENABLE_EXT() my_callback_generic_enable()
      extern bool my_callback_generic_enable(void);
      Note
      After the device enumeration (detecting and identifying USB devices), the USB host starts the device configuration. When the USB generic interface from the device is accepted by the host, the USB host enables this interface and the UDI_HID_GENERIC_ENABLE_EXT() callback function is called and return true. Thus, it is recommended to enable sensors used by the generic in this function.
    • #define UDI_HID_GENERIC_DISABLE_EXT() my_callback_generic_disable()
      extern void my_callback_generic_disable(void);
      Note
      When the USB device is unplugged or is reset by the USB host, the USB interface is disabled and the UDI_HID_GENERIC_DISABLE_EXT() callback function is called. Thus, it is recommended to disable sensors used by the HID generic interface in this function.
    • #define UDI_HID_GENERIC_REPORT_OUT(ptr) my_callback_generic_report_out(ptr)
      extern void my_callback_generic_report_out(uint8_t *report);
      Note
      Callback used to receive the OUT report.
    • #define UDI_HID_GENERIC_SET_FEATURE(f) my_callback_generic_set_feature(f)
      extern void my_callback_generic_set_feature(uint8_t *report_feature);
      Note
      Callback used to receive the SET FEATURE report.
    • #define UDI_HID_REPORT_IN_SIZE 64
      #define UDI_HID_REPORT_OUT_SIZE 64
      #define UDI_HID_REPORT_FEATURE_SIZE 4
      Note
      The report size are defined by the final application.
    • #define UDI_HID_GENERIC_EP_SIZE 64
      Note
      The interrupt endpoint size is defined by the final application.
  2. Send a IN report:

Advanced use cases

For more advanced use of the UDI HID generic module, see the following use cases: