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docs: can send now

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This commit is contained in:
Matthias Ringwald 2016-03-31 15:48:41 +02:00
parent a060793b1c
commit 63759308b7
1 changed files with 36 additions and 20 deletions
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56
doc/manual/docs/protocols.md
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@ -80,7 +80,7 @@ Listing [below](#lst:hciOGFs) shows the OGFs provided by BTstack in file [src/hc
#define OGF_LE_CONTROLLER 0x08
#define OGF_BTSTACK 0x3d
#define OGF_VENDOR 0x3f
~~~~
~~~~
For all existing Bluetooth
commands and their OCFs see [Bluetooth Specification](https://www.bluetooth.org/Technical/Specifications/adopted.htm) -
@ -241,9 +241,11 @@ outgoing packet buffer, or if the ACL buffers in the Bluetooth module
become full, i.e., if the application is sending faster than the packets
can be transferred over the air.
Instead of directly calling *l2cap_send*, it is recommended to first call
*l2cap_can_send_packet_now*. If true, then sending will not fail. If false,
BTstack will emit an L2CAP_EVENT_CAN_SEND_NOW when it is possible to send again.
Instead of directly calling *l2cap_send*, it is recommended to call
*l2cap_request_can_send_now_event* which will trigger an L2CAP_EVENT_CAN_SEND_NOW
as soon as possible. This might be even be immediately from inside the
*l2cap_request_can_send_now_event*. On L2CAP_EVENT_CAN_SEND_NOW, sending to the
channel indicated in the event is guaranteed to succedd.
Listing [below](#lst:L2CAPService)
provides L2CAP service example code.
@ -285,7 +287,7 @@ provides L2CAP service example code.
}
break;
case L2CAP_EVENT_CAN_SEND_NOW:
tryToSend();
send_now();
break;
case L2CAP_EVENT_CHANNEL_CLOSED:
break;
@ -388,11 +390,9 @@ call.
Sending of RFCOMM data packets may fail due to a full internal BTstack
outgoing packet buffer, or if the ACL buffers in the Bluetooth module
become full, i.e., if the application is sending faster than the packets
can be transferred over the air. In such case, the application can try
sending again upon reception of DAEMON_EVENT_HCI_PACKET_SENT or
RFCOMM_EVENT_CREDITS event. The first event signals that the internal
BTstack outgoing buffer became free again, the second one signals that
the remote side allowed to send another packet. Listing [below](#lst:RFCOMMService)
can be transferred over the air.
Listing [below](#lst:RFCOMMService)
provides the RFCOMM service example code.
@ -404,13 +404,13 @@ provides the RFCOMM service example code.
rfcomm_register_service(NULL, rfcomm_channel_nr, mtu);
}
void packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
void packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
if (packet_type == RFCOMM_DATA_PACKET){
// handle RFCOMM data packets
return;
}
...
switch (event) {
switch (packet[0]) {
...
case RFCOMM_EVENT_INCOMING_CONNECTION:
//data: event(8), len(8), address(48), channel(8), rfcomm_cid(16)
@ -456,24 +456,40 @@ assumption, the single output buffer design does not impose additional
restrictions. In the following, we show how this is used for adapting
the RFCOMM send rate.
When there's a need to send a packet, call *rcomm_request_can_send_now*
directly and send the packet when the RFCOMM_EVENT_CAN_SEND_NOW event
gets received.
Before sending data packets, check if RFCOMM can send them by calling
*rfcomm_can_send_packet_now*, as shown in Listing [below](#lst:SingleOutputBufferTryToSend).
~~~~ {#lst:SingleOutputBufferTryToSend .c caption="{Preparing and sending data.}"}
void prepareData(void){
void prepare_data(void){
...
rfcomm_request_can_send_now_event(rfcom_channel_id);
}
void tryToSend(void){
if (!dataLen) return;
if (!rfcomm_channel_id) return;
if (!rfcomm_can_send_packet_now(rfcomm_channel_id)) return;
void send_data(void){
rfcomm_send(rfcomm_channel_id, dataBuffer, dataLen);
// packet is sent prepare next one
prepareData();
prepare_data();
}
void packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
switch (packet_type){
case HCI_EVENT_PACKET:
switch (packet[0]){
...
case RFCOMM_CAN_SEND_NOW:
send_data(;
break;
...
}
...
}
}
}
~~~~
RFCOMM’s mandatory credit-based flow-control imposes an additional