pkt structs definition for better understanding :)
bt_stack:
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struct bt_hci_pkt_acl: |type| header |payload|
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1 HCI_ACL_DATA_PKT_HDR 1
bt_acl_com_stack:
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bt_acl_com_pkt_t : | 1 |HCI_ACL_DATA_PKT_HDR|BT_ACL_COM_HEADER_LEN|BT_MAX_ACL_COM_PAYLOAD|
(array of u_char) ------------------------------------------------------------------------
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bt_acl_com_t : | len | service nr. | payload |
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2 2 BT_MAX_ACL_COM_PAYLOAD
#include <sys/types.h>
#include <bt/bt_defs.h>
| #define BT_ACL_COM_HEADER_LEN 4 |
defines the length of the acl communication header
| #define BT_ERR_ACL_COM_TIMEOUT -2 |
acl pkt error: timeout occured, no pkt with given service number arrived in given time.
| #define BT_ERR_ACL_PAYLOAD_OVERFLOW -3 |
acl pkt error: playload to large
| #define BT_ERR_BUFFER_OVERFLOW 8 |
ack pkt arriving error: internal buffer for ack pkt overflow (due to error pkts that arrived)
| #define BT_ERR_FRAGMENTED_ACL_PKT 4 |
acl pkt arriving error: pkt fragmentation (due to wrong pkt type, use HCI_PACKET_TYPE!)
| #define BT_ERR_INVALID_HANDLE 2 |
acl pkt arriving error: invalid connection handle (due to communication problems)
| #define BT_ERR_INVALID_SERV_NR 1 |
acl pkt arriving error: invalid service number (due to communication problems)
| #define BT_ERR_SERV_NR_OUT_OF_BOUNDS -1 |
acl pkt error: service number out of bounds
| #define BT_MAX_ACL_COM_PAYLOAD 117 |
for not having fragmented pkts we limit the payload of acl for packet type DM3 to 117!! because DM3 acl payload limited to 4+117=121 bytes
| #define HCI_PACKET_TYPE BT_HCI_PACKET_TYPE_DM3 |
Use this packet type to send pkts with a payload up to BT_MAX_ACL_COM_PAYLOAD.
DM3 means three slots are used for one pkt. Smaller amount of slots can lead to fragmented pkts
| #define MAX_SERVICE_NR 8 |
defines the maximal service nr 0 - (MAX_SERVICE_NR-1) that can be given the acl pkts
| typedef struct _bt_acl_com_buffer_entry bt_acl_com_buffer_entry_t |
struct starts with the acl pkt. the con handle holds the handle where the pkt arrived. the state tells about the usage of this buffer entry and the next value points to next entry with same service nr
| typedef u_char bt_acl_com_pkt_t[1+HCI_ACL_DATA_PKT_HDR+BT_ACL_COM_HEADER_LEN+BT_MAX_ACL_COM_PAYLOAD] |
this typedef allocates just enough memory for a acl com pkt with all the header space needed
| typedef struct _bt_acl_com_service bt_acl_com_service_t |
struct to hold for every service (max MAX_SERVICE_NR) a registered event handle to notify a thread and a list of pointer to packets waiting for this thread. service nr equal to the position in the services array!
| typedef struct _bt_acl_com_stack bt_acl_com_stack_t |
holds all the data needed by the acl communication driver
| long bt_acl_com_free_packet | ( | bt_acl_com_stack_t * | _bt_acl_com_stack, | |
| bt_acl_com_pkt_t * | pkt | |||
| ) |
To free the buffer of a acl communication pkt.
It is important to free the receive buffer again after usage!
| _bt_acl_com_stack | Pointer to the acl communication stack | |
| pkt | Packet to be freed |
| char bt_acl_com_get_packet | ( | bt_acl_com_stack_t * | _bt_acl_com_stack, | |
| u_char | service_nr, | |||
| bt_acl_com_pkt_t ** | p_p_pkt, | |||
| bt_hci_con_handle_t * | con_handle, | |||
| u_short * | len, | |||
| u_long | timeout_ms | |||
| ) |
To access the packet this function will return a pointer to the buffer of the packet with service number nr via the argument pointer.
After usage of the packet it is important to call the bt_acl_com_free_packet to avoid acl packet-buffer overflow!
Use bt_acl_com_get_data_pointer to get to the payload data pointer!
| _bt_acl_com_stack | Pointer to the acl communication stack | |
| service_nr | Requested service number (0 - (MAX_SERVICE_NR - 1)) | |
| p_p_pkt | Pass the address of the pointer to a acl com pkt | |
| con_handle | The connection handle where the pkt arrived on | |
| len | length of payload of this pkt | |
| timeout_ms | timeout in milliseconds. Use NUT_WAIT_INFINITE or 0 for no timeout or 1 to check the availability of packets |
| u_char bt_acl_com_get_status | ( | bt_acl_com_stack_t * | _bt_acl_com_stack | ) |
Errors that occure during receiving an acl pkt can be accessed with this function.
After the call the internal error status will be set to 0 again.
Possible errors:
| bt_acl_com_stack_t* bt_acl_com_init | ( | struct btstack * | bt_stack, | |
| u_char | nr_buffer | |||
| ) |
to initialize the acl com stack.
| bt_stack | Pointer to btstack | |
| nr_buffer | Number of receive-buffer for acl com packets |
| void bt_acl_com_print_bt_addr | ( | bt_addr_t | addr | ) |
prints the bt_addr with format: 00:00:00:00:00:00 using normal DEBUGT() call
| void bt_acl_com_print_bt_addr_m | ( | bt_addr_t | addr | ) |
prints the bt_addr with format: 00:00:00:00:00:00 using special DEBUGT_M() call
| long bt_acl_com_send_packet | ( | bt_acl_com_stack_t * | _bt_acl_com_stack, | |
| bt_acl_com_pkt_t * | pkt, | |||
| bt_hci_con_handle_t | con_handle, | |||
| u_short | service_nr, | |||
| u_short | len | |||
| ) |
Function to send a acl communication packet.
Alloc new bt_acl_com_pkt_t and use bt_acl_com_get_data_pointer to access the acl com data area. Send the packet to the connection with con_handle passing the pointer to the bt_acl_com_pkt_t the service number and the length of the acl-com-payload!
e.g.:
bt_acl_com_pkt_t acl_com_pkt; u_char* data = bt_acl_com_get_data_pointer(&acl_com_pkt); strcpy(data, "hello world"); bt_acl_com_send_packet(&acl_com_pkt, <con_handle>, <serv_nr>, 12);
| _bt_acl_com_stack | Pointer to the acl communication stack | |
| pkt | ACL communication packet to be sent | |
| con_handle | Handle of the connection for sending | |
| service_nr | service number (0 - (MAX_SERVICE_NR-1)) | |
| len | length of the acl pkt payload |
1.5.1