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EZConfig is a feature of Si4355/4455 that enables the customer to easily configure the radio by writing a single
configuration array into the chip upon power up, using the EZCONFIG_SETUP command of the API. Generation of
the configuration array content is automated with the Wireless Development Suite (WDS) that is provided free of
charge by Silicon Labs. The WDS saves the user from modifying hundreds of different parameters, which makes
the configuration process easy and straightforward. Based on the parameters entered into the radio configuration
application, the WDS creates the configuration data. If the Launch IDE option is selected, the WDS generates a
radio_config.h header file that contains the configuration data. This header file contains all the information needed
by the application to configure the radio properly. These are the parameters of the RF link such as the modulation
type, channel bandwidth, data rate, center frequency, crystal tolerance, crystal capacitor bank value, modulation
source, CRC calculation and sync word setting. For more information on WDS and EZConfig usage, refer to the
application notes “AN796: Wireless Development Suite General Description” and “AN797: WDS User’s Guide for
EZRadio Devices.”
After the radio chip has been woken up according to the description in the previous chapter, it needs to be
configured with the RF parameters. Using the Radio Control Application, all of the radio related parameters can be
set. On the RF parameters tab, the center carrier frequency, tolerance and frequency of the used crystal, channel
spacing, and the level of the power amplifier can be configured. On the advanced packet handler tab, the length of
the preamble and the pattern of the synchron word can be configured. Manchester coding and the CRC calculation
can be enabled or disabled. The used packet length also can be customized. In addition, the radio can provide a
clock signal through its GPIOs. On the interrupt tab, the interrupt sources of the internal modem of the chip and the
packet handler can be enabled. On the GPIO settings, the four GPIOs, the NIRQ, and the SDO pin can be
configured to one of the 19 available functions including valid preamble output or sync word detect output. Having
configured all the radio parameters, the generated "radio_config.h" header file can be exported from WDS.
Numerous built-in example projects can be opened in Silabs IDE including the newly created header file. All the
example codes can initialize the radio chip by the vRadio_Init( ) function. The header file contains a configuration
array called EZConfig Array and the initialized API properties. The radio chip cannot be used before the EZConfig
array is written into it. Note that using the same radio settings for generating the EZConfig Array does not provide
the same array contents due to the internal encryption method. These values are sent to the radio chip through the
SPI bus by the si4455_write_ezconfig_array( ) function. Since the array is bigger than the total size of the TX and
RX FIFOs, it is divided into parts. Since the EZCONFIG_SETUP command has no any reply, not even CTS, it is
necessary to send a NOP command after each EZCONFIG_SETUP command to be able to check CTS to know
that the chip is ready to receive the next command. The command defined as RF_EZCONFIG_CHECK verifies if
the EZConfig Array was downloaded correctly. The array is secured by a 16-bit CRC to avoid errors during
download. In the event of a CRC mismatch, the radio will drop the configuration array and remains in the
configuration state. The API properties are then configured one by one by the si4455_set_property( ) function.
Finally, the radio gets into ready state and the example code can start to run.
4.6. Radio Configuration File
The configuration file contains API commands to configure the radio and other settings of an example project. It is
interpreted as a C header file called "radio_config.h" that is generated by the "Radio Control Application" of the
WDS for the selected example project. The file consists of several sections.
The head section contains file and copyright info.
The "INPUT DATA" section contains as comments the RF parameter values to be set by the commands defined in
this config file. These RF parameters are derived from the requirements entered by the user in the WDS.
The "CONFIGURATION PARAMETERS" section contains value definitions to be used to set some variables of the
demo project.
The "CONFIGURATION COMMANDS" section contains the definitions of the API commands that will configure the
radio. Also, comments are added that describe the API command in detail.
Next, the "RADIO_CONFIGURATION_DATA_ARRAY" is composed from the previously defined commands
prefixed with command length bytes. Finally, a "RADIO_CONFIGURATION_DATA" structure is composed from the
"RADIO_CONFIGURATION_DATA_ARRAY" and the "CONFIGURATION PARAMETERS". This final structure will
hold all configuration information necessary for the example project.
It is recommended to change the parameters through WDS and not to edit the radio_config.h file directly.
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 ...
