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LPCOpen Platform for NXP LPC Microcontrollers
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USB Interface Management (LPC)

USB Controller definitions for the LPC microcontrollers. More...

Macros

#define USB_STREAM_TIMEOUT_MS   100
 

Enumerations

enum  USB_Modes_t { USB_MODE_None = 0, USB_MODE_Device = 1, USB_MODE_Host = 2, USB_MODE_UID = 3 }
 

Functions

static PRAGMA_ALWAYS_INLINE bool USB_VBUS_GetStatus (void) ATTR_WARN_UNUSED_RESULT ATTR_ALWAYS_INLINE
 Determines if the VBUS line is currently high (i.e. the USB host is supplying power).
 
static PRAGMA_ALWAYS_INLINE void USB_Detach (void) ATTR_ALWAYS_INLINE
 
static PRAGMA_ALWAYS_INLINE void USB_Attach (void) ATTR_ALWAYS_INLINE
 
void USB_Init (void)
 
void USB_Disable (void)
 
void USB_ResetInterface (uint8_t corenum)
 

Variables

volatile uint8_t USB_CurrentMode
 
volatile uint8_t USB_Options
 

USB Controller Option Masks

#define USB_OPT_REG_DISABLED   (1 << 1)
 
#define USB_OPT_REG_ENABLED   (0 << 1)
 
#define USB_OPT_MANUAL_PLL   (1 << 2)
 
#define USB_OPT_AUTO_PLL   (0 << 2)
 

Detailed Description

USB Controller definitions for the LPC microcontrollers.

Functions, macros, variables, enums and types related to the setup and management of the USB interface.

Macro Definition Documentation

#define USB_OPT_AUTO_PLL   (0 << 2)

Automatic PLL control option mask for USB_Init(). This indicates to the library that the library should take full responsibility for controlling the LPC's PLL (used to generate the high frequency clock that the USB controller requires) and ensuring that it is locked at the correct frequency for USB operations.

Definition at line 105 of file USBController_LPC.h.

#define USB_OPT_MANUAL_PLL   (1 << 2)

Manual PLL control option mask for USB_Init(). This indicates to the library that the user application will take full responsibility for controlling the LPC's PLL (used to generate the high frequency clock that the USB controller requires) and ensuring that it is locked at the correct frequency for USB operations.

Definition at line 99 of file USBController_LPC.h.

#define USB_OPT_REG_DISABLED   (1 << 1)

Regulator disable option mask for USB_Init(). This indicates that the internal 3.3V USB data pad regulator should be disabled and the LPC's VCC level used for the data pads.

Note
See USB LPC data sheet for more information on the internal pad regulator.

Definition at line 85 of file USBController_LPC.h.

#define USB_OPT_REG_ENABLED   (0 << 1)

Regulator enable option mask for USB_Init(). This indicates that the internal 3.3V USB data pad regulator should be enabled to regulate the data pin voltages from the VBUS level down to a level within the range allowable by the USB standard.

Note
See USB LPC data sheet for more information on the internal pad regulator.

Definition at line 93 of file USBController_LPC.h.

#define USB_STREAM_TIMEOUT_MS   100

Constant for the maximum software timeout period of the USB data stream transfer functions (both control and standard) when in either device or host mode. If the next packet of a stream is not received or acknowledged within this time period, the stream function will fail.

This value may be overridden in the user project makefile as the value of the USB_STREAM_TIMEOUT_MS token, and passed to the compiler using the -D switch.

Definition at line 116 of file USBController_LPC.h.

Enumeration Type Documentation

Enum for the possible USB controller modes, for initialization via USB_Init() and indication back to the user application via USB_CurrentMode.

Enumerator:
USB_MODE_None 

Indicates that the controller is currently not initialized in any specific USB mode.

USB_MODE_Device 

Indicates that the controller is currently initialized in USB Device mode.

USB_MODE_Host 

Indicates that the controller is currently initialized in USB Host mode.

USB_MODE_UID 

Indicates that the controller should determine the USB mode from the UID pin of the USB connector.

Definition at line 231 of file USBController_LPC.h.

Function Documentation

static void USB_Attach ( void  )
inlinestatic

Attaches the device to the USB bus. This announces the device's presence to any attached USB host, starting the enumeration process. If no host is present, attaching the device will allow for enumeration once a host is connected to the device.

This is inexplicably also required for proper operation while in host mode, to enable the attachment of a device to the host. This is despite the bit being located in the device-mode register and despite the datasheet making no mention of its requirement in host mode.

Definition at line 160 of file USBController_LPC.h.

static void USB_Detach ( void  )
inlinestatic

Detaches the device from the USB bus. This has the effect of removing the device from any attached host, ceasing USB communications. If no host is present, this prevents any host from enumerating the device once attached until USB_Attach() is called.

Definition at line 146 of file USBController_LPC.h.

void USB_Disable ( void  )

Shuts down the USB interface. This turns off the USB interface after deallocating all USB FIFO memory, endpoints and pipes. When turned off, no USB functionality can be used until the interface is restarted with the USB_Init() function.

Definition at line 62 of file USBController_LPC.c.

void USB_Init ( void  )

Main function to initialize and start the USB interface. Once active, the USB interface will allow for device connection to a host when in device mode, or for device enumeration while in host mode.

As the USB library relies on interrupts for the device and host mode enumeration processes, the user must enable global interrupts before or shortly after this function is called. In device mode, interrupts must be enabled within 500ms of this function being called to ensure that the host does not time out whilst enumerating the device. In host mode, interrupts may be enabled at the application's leisure however enumeration will not begin of an attached device until after this has occurred.

Calling this function when the USB interface is already initialized will cause a complete USB interface reset and re-enumeration.

See Also
Device Management for the USB_DEVICE_OPT_* masks.

Definition at line 42 of file USBController_LPC.c.

void USB_ResetInterface ( uint8_t  corenum)

Resets the interface, when already initialized. This will re-enumerate the device if already connected to a host, or re-enumerate an already attached device when in host mode.

Definition at line 89 of file USBController_LPC.c.

static bool USB_VBUS_GetStatus ( void  )
inlinestatic

Determines if the VBUS line is currently high (i.e. the USB host is supplying power).

Note
This function is not available on some AVR models which do not support hardware VBUS monitoring.
Returns
Boolean true if the VBUS line is currently detecting power from a host, false otherwise.

Definition at line 132 of file USBController_LPC.h.

Variable Documentation

volatile uint8_t USB_CurrentMode

Indicates the mode that the USB interface is currently initialized to, a value from the USB_Modes_t enum.

Note
This variable should be treated as read-only in the user application, and never manually changed in value.
When the controller is initialized into UID auto-detection mode, this variable will hold the currently selected USB mode (i.e. USB_MODE_Device or USB_MODE_Host). If the controller is fixed into a specific mode (either through the USB_DEVICE_ONLY or USB_HOST_ONLY compile time options, or a limitation of the USB controller in the chosen device model) this will evaluate to a constant of the appropriate value and will never evaluate to USB_MODE_None even when the USB interface is not initialized.

Definition at line 37 of file USBController_LPC.c.

volatile uint8_t USB_Options

Indicates the current USB options that the USB interface was initialized with when USB_Init() was called. This value will be one of the USB_MODE_* masks defined elsewhere in this module.

Note
This variable should be treated as read-only in the user application, and never manually changed in value.