A N 6 9 2
36
Rev 0.4
5.2.4. Reception of a Simple Packet in Packet Handler Mode
This example project demonstrates the usage of the radio chip for reception in fixed packet length mode and
utilizes the advantages of the Packet Handler feature. This project uses the Human Machine Interface software
module that is used in the transmitter side project as well. The handler functions for the push buttons, LEDs, and
buzzer are also scheduled on a 1 ms time base.
The
DemoApp_Pollhandler()
function also runs outside the scheduled tasks in order to provide fast response if a
radio interrupt occurs. The difference between the transmitter and receiver project scheduled tasks is that the
receiver project uses the Buzzer handler function. This is required as the receiver side beeps when a valid packet
is received. The packet validity has been already verified by the Packet Handler as the CRC calculation is enabled
on the packet payload. The radio interrupt occurs only when a packet with valid CRC is received. The radio won’t
generate interrupt on a packet with a CRC error because this interrupt source is disabled. According to the StartRX
condition in
vRadio_StartRX()
function, the chip remains in RX state in these cases.
The
DemoApp_Pollhandler()
function checks if a valid packet has been received and if it contains the expected
information regarding which button was pressed on the transmitter side. If the information is correct, it blinks the
same LED. The payload has its pre-defined content, namely "BUTTONx" where x can be 1, 2, 3, or 4.
This packet is generally used in different example codes for EZRadio transceivers.
Preamble
Sync Word
Payload
CRC
32-40 bits
2 byte
7+N byte
byte
Number of Bytes
Field Name
Description
4-5
Preamble
0xAA
2
Sync
0x2D, 0xD4
7
Payload
“BUTTONx”
2
CRC-16
Generator X16+X15+X2+1, start value 0xFFFF
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 ...
