doc: add ENABLE_ATT_DELAYED_READ_RESPONSE

doc/manual/docs/how_to.md

@@ -68,22 +68,23 @@ LE_DEVICE_DB_PATH                  | Path to stored LE device information
 BTstack properties:
 
 \#define                         | Description
---------------------------------|---------------------------------------------
+---------------------------------|---------------------------------------------
-ENABLE_CLASSIC                  | Enable Classic related code in HCI and L2CAP
+ENABLE_CLASSIC                   | Enable Classic related code in HCI and L2CAP
-ENABLE_BLE                      | Enable BLE related code in HCI and L2CAP
+ENABLE_BLE                       | Enable BLE related code in HCI and L2CAP
-ENABLE_EHCILL                   | Enable eHCILL low power mode on TI CC256x/WL18xx chipsets
+ENABLE_EHCILL                    | Enable eHCILL low power mode on TI CC256x/WL18xx chipsets
-ENABLE_LOG_DEBUG                | Enable log_debug messages
+ENABLE_LOG_DEBUG                 | Enable log_debug messages
-ENABLE_LOG_ERROR                | Enable log_error messages
+ENABLE_LOG_ERROR                 | Enable log_error messages
-ENABLE_LOG_INFO                 | Enable log_info messages
+ENABLE_LOG_INFO                  | Enable log_info messages
-ENABLE_SCO_OVER_HCI             | Enable SCO over HCI for chipsets (only TI CC256x/WL18xx, CSR + Broadcom H2/USB))
+ENABLE_SCO_OVER_HCI              | Enable SCO over HCI for chipsets (only TI CC256x/WL18xx, CSR + Broadcom H2/USB))
-ENABLE_HFP_WIDE_BAND_SPEECH     | Enable support for mSBC codec used in HFP profile for Wide-Band Speech
+ENABLE_HFP_WIDE_BAND_SPEECH      | Enable support for mSBC codec used in HFP profile for Wide-Band Speech
-ENBALE_LE_PERIPHERAL            | Enable support for LE Peripheral Role in HCI and Security Manager
+ENBALE_LE_PERIPHERAL             | Enable support for LE Peripheral Role in HCI and Security Manager
-ENBALE_LE_CENTRAL               | Enable support for LE Central Role in HCI and Security Manager
+ENBALE_LE_CENTRAL                | Enable support for LE Central Role in HCI and Security Manager
-ENABLE_LE_SECURE_CONNECTIONS    | Enable LE Secure Connections
+ENABLE_LE_SECURE_CONNECTIONS     | Enable LE Secure Connections
 ENABLE_MICRO_ECC_FOR_LE_SECURE_CONNECTIONS | Use [micro-ecc library](https://github.com/kmackay/micro-ecc) for ECC operations
-ENABLE_LE_DATA_CHANNELS         | Enable LE Data Channels in credit-based flow control mode
+ENABLE_LE_DATA_CHANNELS          | Enable LE Data Channels in credit-based flow control mode
-ENABLE_LE_DATA_LENGTH_EXTENSION | Enable LE Data Length Extension support
+ENABLE_LE_DATA_LENGTH_EXTENSION  | Enable LE Data Length Extension support
-ENABLE_LE_SIGNED_WRITE          | Enable LE Signed Writes in ATT/GATT
+ENABLE_LE_SIGNED_WRITE           | Enable LE Signed Writes in ATT/GATT
+ENABLE_ATT_DELAYED_READ_RESPONSE | Enable support for delayed ATT Read operations, see [GATT Server](profiles/#sec:GATTServerProfile)
 ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE | Enable L2CAP Enhanced Retransmission Mode. Mandatory for AVRCP Browsing
 ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL | Enable HCI Controller to Host Flow Control, see below
 ENABLE_CC256X_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND | Enable workaround for bug in CC256x Flow Control during baud rate change, see chipset docs.

doc/manual/docs/profiles.md

@@ -438,7 +438,7 @@ Adding NOTIFY and/or INDICATE automatically creates an addition Client
 Configuration Characteristic.
 
 To require encryption or authentication before a Characteristic can be
-accessed, you can add ENCRYPTION_KEY_SIZE_X - with $X \in [7..16]$ -
+accessed, you can add ENCRYPTION_KEY_SIZE_X - with X in 7..16 -
 or AUTHENTICATION_REQUIRED.
 
 To use already implemented GATT Services, you can import it
@@ -454,6 +454,19 @@ Similar to other protocols, it might be not possible to send any time.
 To send a Notification, you can call *att_server_request_can_send_now*
 to receive a ATT_EVENT_CAN_SEND_NOW event.
 
+If your application cannot handle an ATT Read Request in the *att_read_callback*
+in some situations, you can enable support for this by adding ENABLE_ATT_DELAYED_READ_RESPONSE
+to *btstack_config.h*. Now, you can store the requested attribute handle and return
+*ATT_READ_RESPONSE_PENDING* instead of the length of the provided data when you don't have the data ready. 
+For ATT operations that read more than one attribute, your *att_read_callback*
+might get called multiple times as well. To let you know that all necessary
+attribute handles have been 'requested' by the *att_server*, you'll get a final
+*att_read_callback* with the attribute handle of *ATT_READ_RESPONSE_PENDING*.
+When you've got the data for all requested attributes ready, you can call
+*att_server_read_response_ready*, which will trigger processing of the current request.
+Please keep in mind that there is only one active ATT operation and that it has a 30 second
+timeout after which the ATT server is considered defunct by the GATT Client.
+
 ### Implementing Standard GATT Services {#sec:GATTStandardServices}
 
 Implementation of a standard GATT Service consists of the following 4 steps:

doc/manual/docs/protocols.md

@@ -771,7 +771,7 @@ implementation. The constant data are automatically served by the ATT server upo
 request. To receive the dynamic data, such is characteristic value, the
 application needs to register read and/or write callback. In addition,
 notifications and indications can be sent. Please see Section on 
-[GATT server](section:profiles/#sec:GATTServerProfile) for more.
+[GATT server](profiles/#sec:GATTServerProfile) for more.
 
 ## SMP - Security Manager Protocol {#sec:smpProtocols}