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Android Open Accessory Class Host Mode Driver

Data Structures

struct  USB_ClassInfo_AOA_Host_t
 Android Open Accessory Class Host Mode Configuration and State Structure. More...
 

Macros

#define AOA_ERROR_LOGICAL_CMD_FAILED   0x80
 

Enumerations

enum  AOA_Host_EnumerationFailure_ErrorCodes_t {
  AOA_ENUMERROR_NoError = 0,
  AOA_ENUMERROR_InvalidConfigDescriptor = 1,
  AOA_ENUMERROR_NoCompatibleInterfaceFound = 2,
  AOA_ENUMERROR_PipeConfigurationFailed = 3
}
 

Functions

uint16_t AOA_Host_BytesReceived (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
 
uint8_t AOA_Host_ConfigurePipes (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, uint16_t ConfigDescriptorSize, void *ConfigDescriptorData) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(3)
 
void AOA_Host_CreateBlockingStream (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, FILE *const Stream) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
 
void AOA_Host_CreateStream (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, FILE *const Stream) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
 
uint8_t AOA_Host_Flush (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
 
int16_t AOA_Host_ReceiveByte (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
 
uint8_t AOA_Host_SendByte (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, const uint8_t Data) ATTR_NON_NULL_PTR_ARG(1)
 
uint8_t AOA_Host_SendData (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, const void *const Buffer, const uint16_t Length) ATTR_NON_NULL_PTR_ARG(1)
 
uint8_t AOA_Host_SendString (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, const char *const String) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2)
 
uint8_t AOA_Host_StartAccessoryMode (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
 
void AOA_Host_USBTask (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo) ATTR_NON_NULL_PTR_ARG(1)
 
bool AOA_Host_ValidateAccessoryDevice (USB_ClassInfo_AOA_Host_t *const AOAInterfaceInfo, const USB_Descriptor_Device_t *const DeviceDescriptor, bool *const NeedModeSwitch) ATTR_NON_NULL_PTR_ARG(1) ATTR_NON_NULL_PTR_ARG(2) ATTR_NON_NULL_PTR_ARG(3)
 

Detailed Description

Module Source Dependencies

The following files must be built with any user project that uses this module:

Module Description

Host Mode USB Class driver framework interface, for the Android Open Accessory USB Class driver.

Macro Definition Documentation

#define AOA_ERROR_LOGICAL_CMD_FAILED   0x80

Error code for some Android Open Accessory Host functions, indicating a logical (and not hardware) error.

Enumeration Type Documentation

Enum for the possible error codes returned by the AOA_Host_ConfigurePipes() function.

Enumerator
AOA_ENUMERROR_NoError 

Configuration Descriptor was processed successfully.

AOA_ENUMERROR_InvalidConfigDescriptor 

The device returned an invalid Configuration Descriptor.

AOA_ENUMERROR_NoCompatibleInterfaceFound 

A compatible Android Open Accessory interface was not found in the device's Configuration Descriptor.

AOA_ENUMERROR_PipeConfigurationFailed 

One or more pipes for the specified interface could not be configured correctly.

Function Documentation

uint16_t AOA_Host_BytesReceived ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo)

Determines the number of bytes received by the AOA interface from the device, waiting to be read. This indicates the number of bytes in the IN pipe bank only, and thus the number of calls to AOA_Host_ReceiveByte() which are guaranteed to succeed immediately. If multiple bytes are to be received, they should be buffered by the user application, as the pipe bank will not be released back to the USB controller until all bytes are read.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
Returns
Total number of buffered bytes received from the device.
uint8_t AOA_Host_ConfigurePipes ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
uint16_t  ConfigDescriptorSize,
void *  ConfigDescriptorData 
)

Host interface configuration routine, to configure a given Android Open Accessory host interface instance using the Configuration Descriptor read from an attached USB device. This function automatically updates the given Android Open Accessory Host instance's state values and configures the pipes required to communicate with the interface if it is found within the device. This should be called once after the stack has enumerated the attached device, while the host state machine is in the Addressed state.

Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing an AOA Class host configuration and state.
[in]ConfigDescriptorSizeLength of the attached device's Configuration Descriptor.
[in]ConfigDescriptorDataPointer to a buffer containing the attached device's Configuration Descriptor.
Returns
A value from the AOA_Host_EnumerationFailure_ErrorCodes_t enum.
void AOA_Host_CreateBlockingStream ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
FILE *const  Stream 
)

Identical to AOA_Host_CreateStream(), except that reads are blocking until the calling stream function terminates the transfer. While blocking, the USB and AOA service tasks are called repeatedly to maintain USB communications.

Note
This function is not available on all microcontroller architectures.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class configuration and state.
[in,out]StreamPointer to a FILE structure where the created stream should be placed.
void AOA_Host_CreateStream ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
FILE *const  Stream 
)

Creates a standard character stream for the given AOA Device instance so that it can be used with all the regular functions in the standard <stdio.h> library that accept a FILE stream as a destination (e.g. fprintf). The created stream is bidirectional and can be used for both input and output functions.

Reading data from this stream is non-blocking, i.e. in most instances, complete strings cannot be read in by a single fetch, as the endpoint will not be ready at some point in the transmission, aborting the transfer. However, this may be used when the read data is processed byte-per-bye (via getc()) or when the user application will implement its own line buffering.

Note
The created stream can be given as stdout if desired to direct the standard output from all <stdio.h> functions to the given AOA interface.

This function is not available on all microcontroller architectures.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class configuration and state.
[in,out]StreamPointer to a FILE structure where the created stream should be placed.
uint8_t AOA_Host_Flush ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo)

Flushes any data waiting to be sent, ensuring that the send buffer is cleared.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
Returns
A value from the Pipe_WaitUntilReady_ErrorCodes_t enum.
int16_t AOA_Host_ReceiveByte ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo)

Reads a byte of data from the device. If no data is waiting to be read of if a USB device is not connected, the function returns a negative value. The AOA_Host_BytesReceived() function may be queried in advance to determine how many bytes are currently buffered in the AOA interface's data receive pipe.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
Returns
Next received byte from the device, or a negative value if no data received.
uint8_t AOA_Host_SendByte ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
const uint8_t  Data 
)

Sends a given byte to the attached USB device, if connected. If a device is not connected when the function is called, the byte is discarded. Bytes will be queued for transmission to the device until either the pipe bank becomes full, or the AOA_Host_Flush() function is called to flush the pending data to the host. This allows for multiple bytes to be packed into a single pipe packet, increasing data throughput.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
[in]DataByte of data to send to the device.
Returns
A value from the Pipe_WaitUntilReady_ErrorCodes_t enum.
uint8_t AOA_Host_SendData ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
const void *const  Buffer,
const uint16_t  Length 
)

Sends a given data buffer to the attached USB device, if connected. If a device is not connected when the function is called, the data will be discarded. Bytes will be queued for transmission to the device until either the pipe bank becomes full, or the AOA_Host_Flush() function is called to flush the pending data to the device. This allows for multiple bytes to be packed into a single pipe packet, increasing data throughput.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
[in]BufferPointer to a buffer containing the data to send to the device.
[in]LengthLength of the data to send to the device.
Returns
A value from the Pipe_Stream_RW_ErrorCodes_t enum.
uint8_t AOA_Host_SendString ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
const char *const  String 
)

Sends a given null-terminated string to the attached USB device, if connected. If a device is not connected when the function is called, the string is discarded. Bytes will be queued for transmission to the device until either the pipe bank becomes full, or the AOA_Host_Flush() function is called to flush the pending data to the device. This allows for multiple bytes to be packed into a single pipe packet, increasing data throughput.

Precondition
This function must only be called when the Host state machine is in the HOST_STATE_Configured state or the call will fail.
Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing a AOA Class host configuration and state.
[in]StringPointer to the null terminated string to send to the device.
Returns
A value from the Pipe_Stream_RW_ErrorCodes_t enum.
uint8_t AOA_Host_StartAccessoryMode ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo)

Starts Accessory Mode in the attached Android device. This function will validate the device's Android Open Accessory protocol version, send the configured property strings, and request a switch to Android Open Accessory mode.

Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing an AOA Class host configuration and state.
Returns
A value from the USB_Host_SendControlErrorCodes_t enum, or AOA_ERROR_LOGICAL_CMD_FAILED if a logical error occurred..
void AOA_Host_USBTask ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo)

General management task for a given Android Open Accessory host class interface, required for the correct operation of the interface. This should be called frequently in the main program loop, before the master USB management task USB_USBTask().

Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing an Android Open Accessory Class host configuration and state.
bool AOA_Host_ValidateAccessoryDevice ( USB_ClassInfo_AOA_Host_t *const  AOAInterfaceInfo,
const USB_Descriptor_Device_t *const  DeviceDescriptor,
bool *const  NeedModeSwitch 
)

Validates a device descriptor, to check if the device is a valid Android device, and if it is currently in Android Open Accessory mode.

Parameters
[in,out]AOAInterfaceInfoPointer to a structure containing an AOA Class host configuration and state.
[in]DeviceDescriptorPointer a buffer containing the attached device's Device Descriptor.
[out]NeedModeSwitchPointer to a boolean where the mode switch requirement of the attached device is to be stored.
Returns
Boolean true if the attached device is a valid Android device, false otherwise.