Murata Electronics North America CCT24 用户手册
Page 39 of 90
CCT24
4.0 Protocol Messages
4.1 Protocol Message Formats
The CCT24 is configured and controlled through a series of protocol mode messages. All protocol mode
messages have a common header format:
messages have a common header format:
0
1
2
3 …
SOP
Length
PktType
variable number of arguments …
Figure 4.1.1
The scale above is in bytes.
The Start-of-Packet (SOP) character, 0xFB, is used to distinguish the beginning of a message and to
assure synchronization in the event of a glitch on the serial port at startup.
assure synchronization in the event of a glitch on the serial port at startup.
The Length byte is defined as the length of the remainder of the message following the length byte itself
(or the length of the entire message - 2).
(or the length of the entire message - 2).
The Packet Type (PktType) byte specifies the type of message. It is a bitfield-oriented specifier, decoded
as follows:
as follows:
Bits 7-6
Reserved for future use
Bit 5
Event - set to indicate this message is an event
Bit
4
Reply - set to indicates this message is a reply
Bits 3-0
Type - indicates the message type/command
As indicated, the lower 4 bits (3-0) specify a message type. Bit 4 is a modifier indicating that the message
is a command or a reply. A reply message has the original command type in bits 3:0, with bit 4 set to one.
is a command or a reply. A reply message has the original command type in bits 3:0, with bit 4 set to one.
Arguments vary in size and number depending on the type of message and whether it is a message sent
from the host or is a reply from the radio; see Table 4.1.2.1 below. Messages that are generated on the
serial interface by the user are referred to as host messages. Messages that are generated by the radio
are referred to as reply messages. For many message types, there is a reply message that corresponds
to a host message. For example, when the host sends a TxData message, the radio will reply to indicate
the status of the transmission, whether it succeeded or failed. Some message types are host-only or
reply-only; refer to Table 4.1.2.1 for specifics.
from the host or is a reply from the radio; see Table 4.1.2.1 below. Messages that are generated on the
serial interface by the user are referred to as host messages. Messages that are generated by the radio
are referred to as reply messages. For many message types, there is a reply message that corresponds
to a host message. For example, when the host sends a TxData message, the radio will reply to indicate
the status of the transmission, whether it succeeded or failed. Some message types are host-only or
reply-only; refer to Table 4.1.2.1 for specifics.
4.1.1 Message Types
Each message generally has two forms, a command from the host and a reply from the radio. Depending
on the direction, they have different arguments as shown in Table 4.1.2.1. Event messages from the radio
such as received data packets or status announcements make up a third category of messages. To assist
in interpreting the command-reply data flow, the direction is indicated by the high nibble in the message
type. For example, an EnterProtocolMode command from the host is a message type 0x00, and the
EnterProtocolModeReply from the radio is a message type 0x10. Event messages, including RxData,
RxEvent and Announce packets are indicated by 0x20 in the high nibble of the type byte. If multiple
arguments are to be provided, they are to be concatenated in the order shown. Little-Endian byte format
on the direction, they have different arguments as shown in Table 4.1.2.1. Event messages from the radio
such as received data packets or status announcements make up a third category of messages. To assist
in interpreting the command-reply data flow, the direction is indicated by the high nibble in the message
type. For example, an EnterProtocolMode command from the host is a message type 0x00, and the
EnterProtocolModeReply from the radio is a message type 0x10. Event messages, including RxData,
RxEvent and Announce packets are indicated by 0x20 in the high nibble of the type byte. If multiple
arguments are to be provided, they are to be concatenated in the order shown. Little-Endian byte format