Commands And Responses - Silicon Laboratories Si47 Series Programming Manual

AN332

4. Commands and Responses

Commands control actions, such as power up, power down, or tune to a frequency, and are one byte in size.
Arguments are specific to a given command and are used to modify the command. For example, after the
TX_TUNE_FREQ command, arguments are required to set the tune frequency. Arguments are one byte in size,
and each command may require up to seven arguments. Responses provide the system controller status
information and are returned after a command and its associated arguments are issued. All commands return a
one byte status indicating interrupt state and clear-to-send the next command. Commands may return up to 15
additional response bytes. A complete list of commands is available in "5. Commands and Properties".
Table 2 shows an example of tuning to a frequency using the TX_TUNE_FREQ command. This command requires
that a command and three arguments be sent and returns one status byte. The table is broken into three columns.
The first column lists the action taking place: command (CMD), argument (ARG), status (STATUS), or response
(RESP). The second column lists the data byte or bytes in hexadecimal that are being sent or received. An arrow
preceding the data indicates data being sent from the device to the system controller. The third column describes
the action.
Action
CMD
ARG1
ARG2
ARG3
STATUS
Properties are special command arguments used to modify the default device operation and are generally
configured immediately after power-up. Examples of properties are TX _PREEMPHASIS and REFCLK_FREQ. A
complete list of properties is available in "5. Commands and Properties".
Table 3 shows an example of setting the REFCLK frequency using the REFCLK_FREQ property by sending the
SET_PROPERTY command and five argument bytes. ARG1 of the SET_PROPERTY command is always 0x00.
ARG2 and ARG3 are used to select the property number, PROP (0x0201 in this example), and ARG4 and ARG5
are used to set the property value, PROPD (0x8000 or 32768 Hz in the example).
Action
CMD
ARG1
ARG2 (PROP)
ARG3 (PROP)
ARG4 (PROPD)
ARG5 (PROPD)
STATUS
The implementation of the command and response procedures in the system controller differs for each of the three
bus modes. Section "6. Control Interface" on page 224 details the required bit transactions on the control bus for
each of the bus modes.
6
Table 2. Using the TX_TUNE_FREQ Command
Data
0x30 TX_TUNE_FREQ
0x00
0x27 Set Station to 101.1 MHz
0x7E (0x277E = 10110 with 10 kHz step size)

0x80 Reply Status. Clear-to-send high.
Table 3. Using the SET_PROPERTY Command
Data
0x12 SET_PROPERTY
0x00
0x02 REFCLK_FREQ
0x01
0x80 32768 Hz
0x00

0x80 Reply Status. Clear-to-send high.
Rev. 0.8
Description
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