LLCC68 datasheet(47/111 Pages) SEMTECH

47 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

47 of 111

Semtech

LLCC68

www.semtech.com

7.2 Data Buffer in Receive Mode

In receive mode RxBaseAddr specifies the buffer offset in memory at which the received packet payload data is written. The buffer offset

of the last byte written in receive mode is then stored in RxDataPointer which is initialized to the value of RxBaseAddr at the beginning of

the reception.

The pointer to the first byte of the last packet received and the packet length can be read with the command GetRxbufferStatus().

In single mode, RxDataPointer is automatically initialized to RxBaseAddr each time the transceiver enters Rx mode. In continuous mode the

pointer is incremented starting from the previous position.

7.3 Data Buffer in Transmit Mode

Upon each transition to transmit mode TxDataPointer is initialized to TxBaseAddr and is incremented each time a byte is sent over the air.

This operation stops once the number of bytes sent equals the payloadlength parameter as defined in the function

SetPacketParams(...)

7.4 Using the Data Buffer

RxBaseAddr and TxBaseAddr are both set using the command SetBufferBaseAddresses(...).

By default RxBaseAddr and TxBaseAddr are initialized at address 0x00.

Due to the contiguous nature of the data buffer, the base addresses for Tx and Rx are fully configurable across the 256-byte memory area.

Each pointer can be set independently anywhere within the buffer. To exploit the maximum data buffer size in transmit or receive mode,

the whole data buffer can be used in each mode by setting the base addresses TxBaseAddr and RxBaseAddr at the bottom of the memory

(0x00).

The data buffer is cleared when the device is put into Sleep mode (implying no access). The data is retained in all other modes of operation.

The data buffer is accessed via the command WriteBuffer(...) and ReadBuffer(...). In this function the parameter offset defines

the address pointer of the first data to be written or read. Offset zero defines the first position of the data buffer.

Before any read or write operation it is hence necessary to initialize this offset to the corresponding beginning of the buffer. Upon reading

or writing to the data buffer the address pointer then increments automatically.

Two possibilities exist to obtain the offset value:

• First is to use the RxBaseAddr value since the user defines it before receiving a payload.

• Second, offset can be initialized with the value of RxStartBufferPointer returned by GetRxbufferStatus(...) command.

Note: All the received data is written to the data buffer even if the CRC is invalid, permitting user-defined post processing of

corrupted data. When receiving, if the packet size exceeds the buffer memory allocated for the Rx, it overwrites the transmit portion

of the data buffer.

LLCC68 Folha de dados(PDF) 47 Page - Semtech Corporation