Data Management

RAIL API

Methods for the application to provide and retrieve data from RAIL.

For Transmit the distinction between RAIL_DataMethod_t::PACKET_MODE and RAIL_DataMethod_t::FIFO_MODE has become more cosmetic than functional, as the RAIL_WriteTxFifo() and RAIL_SetTxFifoThreshold() APIs and related RAIL_EVENT_TX_FIFO_ALMOST_EMPTY event can be used in either mode. For Receive the distinction is functionally important because in RAIL_DataMethod_t::PACKET_MODE rollback occurs automatically for unsuccessfully-received packets (RAIL_RxPacketStatus_t ABORT statuses), flushing their data. In RAIL_DataMethod_t::FIFO_MODE rollback is prevented, leaving the data from unsuccessfully-received packets in the receive FIFO for the application to deal with. This allows for packets larger than the receive FIFO size where automatic rollback would corrupt the receive FIFO.

Definition at line 1778 of file rail_types.h.

Receive data sources supported by RAIL.

Note

Data sources other than RX_PACKET_DATA require use of RAIL_DataMethod_t::FIFO_MODE.

Definition at line 1736 of file rail_types.h.

Transmit data sources supported by RAIL.

Definition at line 1709 of file rail_types.h.

RAIL data management configuration.

Parameters

[in]	railHandle	A RAIL instance handle.
[in]	dataConfig	RAIL data configuration structure.

Returns

Status code indicating success of the function call.

This function configures how RAIL manages data. The application can configure RAIL to receive data in a packet-based or FIFO-based manner. RAIL_DataMethod_t::FIFO_MODE is necessary to receive packets larger than the radio's receive FIFO. It is also required for receive data sources other than RAIL_RxDataSource_t::RX_PACKET_DATA.

Generally with RAIL_DataMethod_t::FIFO_MODE, the application sets appropriate FIFO thresholds via RAIL_SetTxFifoThreshold() and RAIL_SetRxFifoThreshold() and then enables and handles the RAIL_EVENT_TX_FIFO_ALMOST_EMPTY event callback (to feed more packet data via RAIL_WriteTxFifo() before the FIFO underflows) and the RAIL_EVENT_RX_FIFO_ALMOST_FULL event callback (to consume packet data via RAIL_ReadRxFifo() before the receive FIFO overflows).

When configuring TX for RAIL_DataMethod_t::FIFO_MODE, this function resets the transmit FIFO. When configuring TX or RX for RAIL_DataMethod_t::PACKET_MODE, this function will reset the corresponding FIFO thresholds such that they won't trigger the RAIL_EVENT_RX_FIFO_ALMOST_FULL or RAIL_EVENT_TX_FIFO_ALMOST_EMPTY events.

When RAIL_DataConfig_t::rxMethod is set to RAIL_DataMethod_t::FIFO_MODE, the radio won't drop packet data of aborted or CRC error packets, but will present it to the application to deal with accordingly. On completion of erroneous packets, the RAIL_Config_t::eventsCallback with RAIL_EVENT_RX_PACKET_ABORTED, RAIL_EVENT_RX_FRAME_ERROR, or RAIL_EVENT_RX_ADDRESS_FILTERED will tell the application it can drop any data it read via RAIL_ReadRxFifo() during reception. For CRC error packets when the RAIL_RX_OPTION_IGNORE_CRC_ERRORS RX option is in effect, the application should check for that from the RAIL_RxPacketStatus_t obtained by calling RAIL_GetRxPacketInfo(). RAIL will automatically flush any remaining packet data after reporting one of these packet completion events or the application can explicitly flush it by calling RAIL_ReleaseRxPacket().

When RAIL_DataConfig_t::rxMethod is set to RAIL_DataMethod_t::PACKET_MODE, the radio will roll back (drop) all packet data associated with aborted packets including those with CRC errors (unless configured to ignore CRC errors via the RAIL_RX_OPTION_IGNORE_CRC_ERRORS RX option). The application will never have to deal with packet data from these packets. In either mode, the application can set RX options as needed.

When RAIL_DataConfig_t::rxSource is set to a value other than RX_PACKET_DATA and RAIL_Config_t::eventsCallback RAIL_EVENT_RX_FIFO_OVERFLOW is enabled RX will be terminated if a RX FIFO overflow occurs. If RAIL_EVENT_RX_FIFO_OVERFLOW is not enabled, data will be discarded until the overflow condition is resolved. To continue capturing data RX must be restarted using RAIL_StartRx().

Get the number of bytes used in the receive FIFO.

Only use this function in RX RAIL_DataMethod_t::FIFO_MODE. Apps should use RAIL_GetRxPacketInfo() instead.

Parameters

[in]

railHandle

A RAIL instance handle.

Returns

Number of bytes used in the receive FIFO.

This function indicates how much packet-related data exists in the receive FIFO that could be read.

Note

The number of bytes returned may not just reflect the current packet's data but could also include raw appended info bytes added after successful packet reception and bytes from subsequently received packets. It is up to the app to never try to consume more than the packet's actual data when using the value returned here in a subsequent call to RAIL_ReadRxFifo(), otherwise the receive FIFO will be corrupted.

Get the RAIL receive FIFO almost full threshold value.

Parameters

[in]

railHandle

A RAIL instance handle.

Returns

Configured RX Threshold value.

Retrieves the configured RX threshold value.

Get the number of bytes unused in the transmit FIFO.

Parameters

[in]

railHandle

A RAIL instance handle.

Returns

Number of bytes unused in the transmit FIFO.

This function indicates how much space is available in the transmit FIFO for writing additional packet data.

Get the RAIL transmit FIFO almost empty threshold value.

Parameters

[in]

railHandle

A RAIL instance handle.

Returns

Configured TX Threshold value.

Retrieves the configured TX threshold value.

Read packet data from RAIL's internal receive FIFO.

Parameters

[in]	railHandle	A RAIL instance handle.
[out]	dataPtr	An application-provided pointer to store data. If NULL, the data is thrown away rather than copied out.
[in]	readLength	A number of packet bytes to read from the FIFO.

Returns

The number of packet bytes read from the receive FIFO.

This function reads packet data from the head of receive FIFO and writes it to the provided dataPtr. It does not permit reading more data than is available in the FIFO, nor does it permit reading more data than remains in the oldest unreleased packet.

Because this function does not have a critical section, use it only in one context or make sure function calls are protected to prevent buffer corruption.

Warning

This function is intended for use only with RAIL_DataMethod_t::FIFO_MODE and should never be called in RAIL_DataMethod_t::PACKET_MODE where it could lead to receive FIFO corruption.

Note

When reading data from an arriving packet that is not yet complete, keep in mind its data is highly suspect because it has not yet passed any CRC integrity checking. Also note that the packet could be aborted, canceled, or fail momentarily, invalidating its data in Packet mode. Furthermore, there is a small chance towards the end of packet reception that the receive FIFO could include not only packet data received so far, but also some raw radio-appended info detail bytes that RAIL's packet-completion processing will subsequently deal with. It's up to the application to know its packet format well enough to avoid reading this info because it will corrupt the packet's details and possibly corrupt the receive FIFO.

Reset the RAIL transmit and/or receive FIFOs.

Parameters

[in]	railHandle	A RAIL instance handle.
[in]	txFifo	If true, reset the transmit FIFO.
[in]	rxFifo	If true, reset the receive FIFO.

This function can reset each FIFO independently. The application should not reset the receive FIFO while receiving a frame, nor should it reset the transmit FIFO while transmitting a frame.

Set the address of the receive FIFO, a circular buffer used for RX data.

Parameters

[in]	railHandle	A RAIL instance handle.
[in,out]	addr	A pointer to a read-write memory location in RAM used as the receive FIFO. This memory must persist until the next call to this function.
[in,out]	size	A desired size of the receive FIFO in bytes. This will be populated with the actual size during the function call.

Returns

Status code indicating success of the function call.

This function sets the memory location for the receive FIFO. It must be called at least once before any receive operations occur.

Note

After it is called, any prior receive FIFO is orphaned. To avoid orphaning the default internal 512-byte receive FIFO so it does not unnecessarily consume RAM resources in your application, implement RAILCb_SetupRxFifo() to call this function.

FIFO size can be determined by the return value of this function. The chosen size is determined based on the available FIFO sizes supported by the hardware. Similarly, some hardware has stricter FIFO alignment requirements; 32-bit alignment provides the maximum portability across all RAIL platforms. For more on supported FIFO sizes and alignments, see chip-specific documentation, such as EFR32. The returned FIFO size will be the closest allowed size less than or equal to the passed in size parameter, unless the size parameter is smaller than the minimum FIFO size.

This function reserves the block of RAM starting at addr with a length of size, which is used internally as a circular buffer for the receive FIFO. It must be able to hold the entire FIFO size. The caller must guarantee that the custom FIFO remains intact and unchanged (except via incoming packet data being written) until the next call to this function.

In multiprotocol, RAIL currently shares one receive FIFO across all protocols. This function will return RAIL_STATUS_INVALID_STATE if the requested RAIL_Handle_t is not active.

Configure the RAIL receive FIFO almost full threshold.

Parameters

[in]	railHandle	A RAIL instance handle.
[in]	rxThreshold	The threshold above which the RAIL_EVENT_RX_FIFO_ALMOST_FULL event will fire.

Returns

Configured receive FIFO threshold value.

This function configures the threshold for the receive FIFO. When the number of bytes of packet data in the receive FIFO exceeds the configured threshold, RAIL_Config_t::eventsCallback will fire with RAIL_EVENT_RX_FIFO_ALMOST_FULL set. The rxThreshold value should be smaller than the receive FIFO size; anything else, including a value of RAIL_FIFO_THRESHOLD_DISABLED, will disable the threshold, returning RAIL_FIFO_THRESHOLD_DISABLED.

Set the address of the transmit FIFO, a circular buffer used for TX data.

Parameters

[in]	railHandle	A RAIL instance handle.
[in,out]	addr	A pointer to a read-write memory location in RAM used as the transmit FIFO. This memory must persist until the next call to this function.
[in]	initLength	A number of initial bytes already in the transmit FIFO.
[in]	size	A desired size of the transmit FIFO in bytes.

Returns

Returns the FIFO size in bytes.

This function sets the memory location for the transmit FIFO. It must be called at least once before any transmit operations occur.

FIFO size can be determined by the return value of this function. The chosen size is determined based on the available FIFO sizes supported by the hardware. Similarly, some hardware has stricter FIFO alignment requirements; 32-bit alignment provides the maximum portability across all RAIL platforms. For more on supported FIFO sizes and alignments, see chip-specific documentation, such as EFR32. The returned FIFO size will be the closest allowed size less than or equal to the passed in size parameter, unless the size parameter is smaller than the minimum FIFO size. If the initLength parameter is larger than the returned size, the FIFO will be filled up to its size.

A user may write to the custom memory location directly before calling this function, or use RAIL_WriteTxFifo to write to the memory location after calling this function. Users must specify the initLength for previously-written memory to be set in the transmit FIFO.

This function reserves the block of RAM starting at addr with a length of the returned FIFO size, which is used internally as a circular buffer for the transmit FIFO. It must be able to hold the entire FIFO size. The caller must guarantee that the custom FIFO remains intact and unchanged (except via calls to RAIL_WriteTxFifo) until the next call to this function.

Note

The protocol's packet configuration, as set up by the radio configurator or via RAIL_SetFixedLength(), determines how many bytes of data are consumed from the transmit FIFO for a successful transmit operation, not the initLength value passed in. If not enough data has been put into the transmit FIFO, a RAIL_EVENT_TX_UNDERFLOW event will occur. If too much data is put into the transmit FIFO, the extra data will either become the first bytes sent in a subsequent packet, or will be thrown away if the FIFO gets reset prior to the next transmit. In general, the proper number of packet bytes to put into the transmit FIFO are all payload bytes except for any CRC bytes which the packet configuration causes to be sent automatically.

Configure the RAIL transmit FIFO almost empty threshold.

Parameters

[in]	railHandle	A RAIL instance handle.
[in]	txThreshold	The threshold below which the RAIL_EVENT_TX_FIFO_ALMOST_EMPTY event will fire.

Returns

Configured transmit FIFO threshold value.

This function configures the threshold for the transmit FIFO. When the number of bytes in the transmit FIFO falls below the configured threshold, RAIL_Config_t::eventsCallback will fire with RAIL_EVENT_TX_FIFO_ALMOST_EMPTY set. The txThreshold value should be smaller than or equal to the transmit FIFO size; higher values will be pegged to the FIFO size. A value of 0 or RAIL_FIFO_THRESHOLD_DISABLED will disable the threshold, returning RAIL_FIFO_THRESHOLD_DISABLED.

Write data to the transmit FIFO previously established by RAIL_SetTxFifo().

Parameters

[in]	railHandle	A RAIL instance handle.
[in]	dataPtr	An application-provided pointer to transmit data.
[in]	writeLength	A number of bytes to write to the transmit FIFO.
[in]	reset	If true, resets transmit FIFO before writing the data.

Returns

The number of bytes written to the transmit FIFO.

This function reads data from the provided dataPtr and writes it to the transmit FIFO that was previously established by RAIL_SetTxFifo(). If the requested writeLength exceeds the current number of bytes open in the transmit FIFO, the function only writes until the transmit FIFO is full. The function returns the number of bytes written to the transmit FIFO or returns zero if railHandle is NULL or if the transmit FIFO is full.

Note

The protocol's packet configuration, as set up by the radio configurator or via RAIL_SetFixedLength(), determines how many bytes of data are consumed from the transmit FIFO for a successful transmit operation, not the writeLength value passed in. If not enough data has been put into the transmit FIFO, a RAIL_EVENT_TX_UNDERFLOW event will occur. If too much data is put into the transmit FIFO, the extra data will either become the first bytes sent in a subsequent packet, or will be thrown away if the FIFO gets reset prior to the next transmit. In general, the proper number of packet bytes to put into the transmit FIFO are all payload bytes except for any CRC bytes, which the packet configuration causes to be sent automatically.

This function does not create a critical section but, depending on the application, a critical section could be appropriate.

Set up the receive FIFO to use.

This function is optional to implement.

Parameters

[in]

railHandle

A RAIL instance handle.

Returns

Status code indicating success of the function call.

This function is called during the RAIL_Init process to set up the FIFO to use for received packets. If not implemented by the application, a default implementation from within the RAIL library will be used to initialize an internal default 512-byte receive FIFO.

If this function returns an error, the RAIL_Init process will fail.

During this function, the application should generally call RAIL_SetRxFifo. If that does not happen, the application needs to set up the receive FIFO via a call to RAIL_SetRxFifo before attempting to receive any packets. An example implementation may look like the following: