Standby Mode; Frequency Synthesis Mode (Fs); Transmit Mode (Tx) - ST STM32WL55JC Reference Manual

Sub-GHz radio (SUBGHZ)
BUSY timing is shown in the figure below.
For the different mode transitions, typical busy timing values are given in the table below.
Sleep-to-Standby (no data retention)
Sleep-to-Standby (with data
Standby-to-Standby with HSE32
Standby (HSE32 off)-to-FS
Standby (HSE32 off)-to-TX
Standby (HSE32 off)-to-RX
Standby (HSE32 on)-to-FS
Standby (HSE32 on)-to-TX
Standby (HSE32 on)-to-RX
1. When entering FS mode, BUSY is cleared to 0 when RF-PLL is locked.
2. When entering TX mode, BUSY is cleared to 0 when the PA ramps up and the transmission of
preamble starts.
3. When entering RX mode, BUSY is cleared to 0 when the receiver is ready to receive data.
5.8 Sub-GHz radio SPI interface
The sub-GHz radio SPI slave interface gives access to the sub-GHz radio configuration,
registers and buffer memory, through SPI commands. It is connected to the SUBGHZSPI
master interface peripheral on the CPU bus matrix.
For a write access, an opcode byte is sent followed by sending the command parameter
bytes.
For a read access, an opcode byte is sent followed by receiving data bytes.
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Figure 16. Sub-GHz radio BUSY timing
BUSY
NSS
SPI
Opcode
Table 33. Operation mode transition BUSY switching time
Mode transition
retention)
(1)
(2)
(3)
(1)
(2)
(3)
(2)
FS-to-TX
(3)
FS-to-RX
Param 1 Param n
Write command
SPI command (sub-GHz radio event)
SPI NSS low 20 μs
SPI NSS low 20 μs (RTC end-of-count)
Set_Standby()
Set_Fs()
all Set_Tx()
Set_Rx(), Set_Cad()
Set_Fs()
all Set_Tx()
Set_Rx(), Set_Cad()
all Set_Tx()
Set_Rx(), Set_Cad()
RM0453 Rev 2
t
SW
t
SWMODE
t
typical (μs)
RM0453
MSv64330V1
SWMODE
3500
340
31
50
126
83
40
105
62
76
41