Texas Instruments Chipcon CC2400DBK, Руководство пользователя, Страница: 28 / 31

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Utility.c
Configure output profile
The CC2400 Development Environment “build process” generates an executable file
according to the settings specified in the make file provided with the application examples
and by using the macros configured in the text editor. To support the processor target the
output file must be in the correct format.
With CC2400DB an RF link example is provided in the application code section of the
processor flash. The example is called rfBlinkLed. The application program is controlled by
the same push button as the bootloader, S2. See schematic layout for location of the button
on the PCB. Instead of powering up the board with the bootloader the board should be
powered up with the application code. The CC2400 is configured with default settings,
buffered mode, and a data rate of 1 Mbps.
Use the S2 push button to start the application. You will see that if you have no receiver up
and running the red LED will start to toggle. This means that you are not receiving
acknowledge form the receiver and thus have no link.
Data packet description
The data packet consists of a preamble, synchronization word, length byte, flag byte and a
data field. The length byte, flag byte and a fixed 10-byte payload are inserted by the
application.
The preamble, synchronization word and CRC is generated and inserted in the package by
CC2400. The data packet is shown in the figure 18.
LENGTH Preamble SOF FLAGS PAYLOAD CRC
Inserted by CC2400
Figure 18 The data packet used in the rfBlinkLed example
Data transmission protocol
The data transmission protocol is very simple, only using packet acknowledgement (ACK).
When the receiver receives a data package, the packet type is checked for CRC. If the
message is OK, it is shown on the green receiver LED, and an acknowledgement is sent as a
reply. However, if an acknowledgement packet that is received by the transceiver originally
transmitting, receival of the ACK is indicated on the yellow LED without any further reply. If no
acknowledgement is received the red LED will toggle.
DEVICE 1
DEVICE 2
Receiver polling
Initial
trans -
mission
LED (ACK)
RX LED TX ACK
TX RX
Ack.
trans -
mission Acknowledge
shown on
Transceiver LED
DEVICE 1
DEVICE 2
Receiver polling
Initial
trans -
mission
LED (ACK)
RX
LED
TX ACK
TX RX
Ack.
trans -
mission Acknowledge
shown on
LED
Device is active as
long as S2 push
button is held down
Message
shown on
receiver LED Message
shown on
receiver LED
Figure 19 Data Transmission Protocol