蓝牙BLE ATT剖析（二）-- PDU

一.Error Handling

Error Response

The Error Responseis used to state that a given request cannot be performed, and to provide the reason.
Note: The Write Command does notgenerate an Error Response

二.MTU Exchange

1.Exchange MTU Request

The Exchange MTU Requestis used by the client toinform the server of the client’s maximum receive MTU size and requestthe server to respond with its maximum receive MTU size.

2.Exchange MTU Response

The Exchange MTU Responseis sent in reply to a received Exchange MTU Request.

三.Find Information

1.Find Information Request

The Find Information Requestis used to obtain the mapping of attribute handles with their associated types. This allows a client to discover the list of attributes and their types on a server

2. Find Information Response

The Find Information Responseis sent in reply to a received Find Information Requestand contains information about this server

3.Find By Type Value Request

The Find By Type Value Requestis used to obtain the handles of attributes that have a 16-bit UUID attribute type and attribute value.This allows the range of handles associated with a given attribute to be discovered when the attribute type determines the grouping of a set of attributes. Note: Generic Attribute Profile defines grouping of attributes by attribute type.
4.Find By Type Value Response
The Find By Type Value Responseis sent in reply to a received Find By Type Value Requestand contains information about this server

四.Reading Attributes

1.Read By Type Request

The Read By Type Requestis used to obtain the values of attributes where the attribute type is known butthe handle is not known

2.Read ByType Response

The Read By Type Responseis sent in reply to a received Read By Type Requestand contains the handles and values of the attributesthat have been read

3.Read Request

The Read Requestis used to request the serverto read the value of an attribute and returnits value in a Read Response

4.Read Response

The read response is sent in reply toa received Read Requestand contains the value of the attribute that has been read

例：

5.Read Blob Request

The Read Blob Requestis used to request the server to read part of the value of an attribute at a given offset and return a specific part of the value in a Read Blob Response.

6.ReadBlob Response

The Read Blob Responseis sent in reply to a received Read Blob Requestand contains part of the value of the attribute that has been read.

7.Read Multiple Request

The Read Multiple Requestis used to request the server to read two or more values of a set of attributesand return their values in a Read Multiple Response. Only values that have a known fixed size can be read, with the exception of the last value that can have a variable length. The knowledge of whether attributes have a known fixed size is defined in a higher layer specification.

8.Read Multiple Response

The read response is sent in reply toa received Read Multiple Requestand contains the values of the attributes that have been read

9.Read by Group Type Request

The Read By Group Type Requestis used to obtain the values of attributes where the attribute type is known, the type of a grouping attribute as defined by a higher layer specification,but the handle is not known.

10.Read by Group Type Response

The Read By Group Type Responseis sent in reply to a received Read By Group Type Requestand contains the handles and values of the attributes that have been read

五.Writing Attributes

1.Write Request

The Write Requestis used to request the server to write the value of an attribute and acknowledge thatthis has been achieved in a Write Response

2.Write Response

The Write Responseis sent in reply to a valid Write Requestand acknowledges that the attribute has been successfully written

例：

3.Write Command

The Write Command is used to request the server to write the value of an attribute, typically into a control-pointattribute.

例：

4.Signed Write Command

The Signed Write Commandis used to request the serverto write the value of an attribute with an authentication signature, typically into a control-point attribute

六.Signed Write Command

The Signed Write Commandis used to request the serverto write the value of an attribute with an authentication signature, typically into a control-point attribute

七.ServerInitiated

1.Handle Value Notification

A server can send a notification of an attribute’s value at any time

例:

2.Handle Value Indication

A server can send an indication of an attribute’s value

3.Handle Value Confirmation

The Handle Value Confirmationis sent in response to a received Handle Value Indicationand confirms that the client has received an indication of the given attribute.