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34
Rev 0.4
5.2.3. Transmission of a Simple Packet in Packet Handler Mode
This example project demonstrates the usage of the radio chip in fixed packet length mode and utilizes the
advantages of the Packet Handler feature.
This example project uses the radio to transmit the “BUTTONx” packets, where “x” value can be “1–4” depending
on which button was pressed. Once the packet is sent to the radio, it blinks the corresponding LED on the board.
The transmitter part of this example project configures the radio parameters such as frequency, data rate, and
modulation using the EZConfig Array generated by WDS. It also sets the Packet Handler properties to use fixed
packet length with CRC check.
These custom properties enable the Packet Handler interrupts and the packet sent interrupt source.
The application code uses the Human Machine Interface software module in order to handle the push button
events and blink LEDs. Both handler functions are scheduled to run once in every 1 ms.
The
Demo_App_Pollhandler()
function is outside of the scheduled tasks to guarantee the fast response if a radio
interrupt occurs. These timing intervals are generated by the Timer2 peripheral overflow interrupt. The Interrupt
Service Routine (ISR) for this interrupt can be found in
isr.c
source file.
The
DemoApp_Pollhandler()
function continuously checks if the packet has been sent by checking the Packet
Handler interrupt of the radio. When a packet is successfully sent, the function blinks the LED corresponding to the
pressed button.
In order to limit the packet resending frequency, there is a
PACKET_SEND_INTERVAL
macro defined. After a
packet starts to transmit, the next packet transmission can be started only after the defined time interval elapsed.
The return value of the
vSampleCode_SendFixPacket()
function is TRUE when a button pressed event has
occurred. This also means that a packet has been written to the radio FIFO and is waiting for transmission. The
used packet structure is shown in the following table:
Preamble
Sync Word
Payload
CRC
32–40 bits
2 byte
7 byte
byte
Summary of Contents for Si4455 Series
Page 8: ...AN692 8 Rev 0 4 Figure 6 Device Configuration Options ...
Page 22: ...AN692 22 Rev 0 4 Figure 21 Supply Current versus Time Diagram from Shutdown to RX State ...
Page 23: ...AN692 Rev 0 4 23 4 4 Radio Chip Waking Up Figure 22 Radio Wake Up Process ...
Page 35: ...AN692 Rev 0 4 35 Figure 32 Transmission Flowchart ...
Page 39: ...AN692 Rev 0 4 39 Figure 33 Reception Flowchart ...
Page 41: ...AN692 Rev 0 4 41 Figure 34 Bidirectional Variable Packet Example Project Flowchart ...
Page 47: ...AN692 Rev 0 4 47 Figure 41 Long Packet Transmission Flowchart ...
Page 48: ...AN692 48 Rev 0 4 Figure 42 Long Packet RX Flowchart ...
