9.2 HCI Command Packet – Host Buffer Size (Opcode – 0x0C33)

The host MCU uses the host buffer size (opcode – 0x0C33) command to notify the BM70/71 module about the maximum length and the number of messages that the host MCU can receive. There is a large amount memory available for buffer space in the host, and the BM70/71 module can only send the amount of data that is limited to the internal buffer size. This is because the host MCU must not send an HCI command or HCI-ISDAP command packet with an amount of data which exceeds the size of the buffers in the BM70/71 module. For more details about determining values of the buffer size, refer to HCI Command Packet – Read Buffer Size (Opcode – 0x1005). Therefore, the amount of data in the BM70/71 module response is limited to this size.

Command Format – Host MCU to BM70/71 Module

Table 9-4. Host Buffer Size Command Format
	Start	Opcode	Length	Data
Byte Number	0	1	3	4-10
Size (bytes)	1	1-2	1	7
Value	0x01	0x0C33	7	See the following table

Note: The opcode field for the HCI vendor command is formatted as LE. For the opcode (0x0C33), byte[1] is 0x33, byte[2] is 0x0C.

Table 9-5. Data Field Parameters
Byte Number	Value	Parameter Description	Length
4-5	0xXXXX	HCI-ISDAP command packet length. This is maximum acceptance length of the host MCU in bytes of the data portion of an HCI-ISDAP command packet. The BM70/71 module does not send any message that exceeds this length.	2 bytes
6	0xXX	Synchronous data packet length (HCI-ISDAP command) in bytes that the host MCU can accept.	1 byte
7-8	0xXX	Total number of HCI-ISDAP command packets. This is the number of packets, the host MCU can store in the buffer(s). The BM70/71 module does not send multiple packets exceeding this value.	2 bytes
9-10	0xXX	Total number of synchronous data packets the host MCU can store.	2 bytes

Figure 9-2. Message Sequence for Host Buffer Size

Response Format – BM70/71 Module to Host MCU

The BM70/71 module responds to this command with an HCI event response – command complete (opcode – 0x0E) packet with no additional parameters returned. For more details, refer to Command Complete Event (Opcode – 0x0E).