Receive Data Buffer Operation; Transmit Data Buffer Operation; Sub-Ghz Radio Operating Modes - ST STM32WL5 Series Reference Manual

RM0453
5.6.1

Receive data buffer operation

In receive mode, RxBaseAddr, configured through Set_BufferBaseAddress(),
determines the receive buffer offset in the sub-GHz radio RAM. RxBaseAddr can be set
anywhere within the RAM data buffer. If needed, the whole 256-byte RAM data buffer can
be used.
For the first received packet, RxStartBufferPointer is set to RxBaseAddr. The first byte of the
first received packet payload data is written at the RxStartBufferPointer address. The last
byte of the received packet payload data is written at the address determined by
RxStartBufferPointer + RxPayloadLength. RxStartBufferPointer and RxPayloadLength can
be read by Get_RxBufferStatus() command.
In single receive and listening modes, RxStartBufferPointer is automatically initialized to
RxBaseAddr for each new reception when the sub-GHz radio enters RX mode.
In continuous receive mode, RxStartBufferpointer is continuously incremented from the
position at which it was left by the previous received packet. In this mode, subsequent
received packets are stored continuous in the RAM data buffer.
Caution: If the amount of received data exceeds the defined receive buffer size, other data in the
RAM are overwritten.
Receive data are written to the receive data buffer regardless of the received CRC status.
When the received CRC fails, post processing on the incorrectly received data can still be
performed by the CPU.
Caution: When the received packet length exceeds the area allocated to the receive data buffer, it
may overwrite the transmit data buffer area in the RAM data buffer.
5.6.2

Transmit data buffer operation

In transmit mode, TxBaseAddr determines the transmit buffer offset in the sub-GHz radio
RAM. For each transmission, when the sub-GHz radio enters TX mode, TxBufferPointer is
automatically initialized to TxBaseAddr. Each time a payload byte is transmitted,
TxBufferPointer is incremented until all bytes, according the PayloadLength set by the
Set_PacketParams() command, are transmitted.
5.7

Sub-GHz radio operating modes

After a sub-GHz radio reset, a startup phase is initiated. As BUSY is active during this
phase, commands cannot be accepted. When supply and clock are available to the sub-
GHz radio, BUSY is deactivated and the CPU can take control.
The sub-GHz radio provides the following operating modes:
• Sleep mode
–
–
–
–
Deep-Sleep: all sub-GHz radio clocks are turned off and data memory is lost
RC 13 MHz clock turned off
RC 64 kHz and timers can be kept running (optional)
Optional registers and data memory retained
RM0453 Rev 1
Sub-GHz radio (SUBGHZ)
169/1461
218