Sub-GHz radio (SUBGHZ) RM0453
168/1454 RM0453 Rev 2
5.5.7 BPSK framing
The BPSK packet framing is used with the BPSK and (D)BPSK modems. The BPSK packet
framing can be configured by Set_PacketParams() command and allows the total frame
length definition. The full packet (preamble, synch word, device id to CRC) must be provided
in the transmit data buffer.
5.6 Sub-GHz radio data buffer
The sub-GHz radio uses a 256-byte RAM data buffer that is accessible by the CPU through
the SUBGHZSPI interface in all sub-GHz radio operating modes except Sleep and
Deep-Sleep. The RAM data buffer is cleared in Deep-Sleep mode, optionally retained in
Sleep mode and always retained in all other modes. In Sleep and Deep-Sleep modes, the
TxBaseAddr and RxBaseAddr values are lost. In order to retrieve data after Sleep mode
retention, the default values must be used (TxBaseAddr = 0x80 and RxBaseAddr = 0x00),
or RxPayloadLength and RxStartBufferPointer must be stored in the CPU memory.
On die revision Y and later, the PayloadLength can be updated during transmission. This
capability allows the support of long packets.
On previous die revisions, the PayloadLength is fixed (latched in the radio) after a SetTx()
command.
The RAM data buffers are fully configurable. They allow access to the transmit data buffer
and the last receive data buffer. The RAM data buffer organization is depicted in the figure
below.
Figure 14. Sub-GHz RAM data buffer operation
The RAM data buffer is accessed by Write_Buffer() and Read_Buffer()commands.
The offset parameter defines the address in the SRAM data buffer. To read the first byte
MSv62621V2
RAM data
buffer
Transmit
data buffer
Receive
data buffer
CPU side Sub-GHz radio side
TxBaseAddr + RTxPayloadLength
TxBaseAddr
TxBufferPointer
RxBaseAddr
RxStartBufferPointer + RTxPayloadLength
RxStartBufferPointer
Write_Buffer()
Read_Buffer()
address 0x00
address 0xFF
Last received
payload
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