Texas Instruments SimpleLink CC2620 Technical Reference Manual page 1488

RF Core HAL
23.3.2.7.5 Partial Read RX Entry
Proprietary mode supports an RX entry where the data can be read before the entire packet is received
over the air, which can be used for the following purposes:
• When data must be read before the entire packet is received
• When the length of the packet is not known in the beginning of the packet
• When the length of the packet is too long for the entire payload to be kept in memory simultaneously
To support this, a special variant of the structure in
several entry elements may be contained in the same entry. Each entry element corresponds to one
packet received over the air, or part of it. The element may also contain additional fields. This type is
selected by setting config.type to 3. In the multielement entry, the data field is composed as shown in
Table 23-13 (the indexes are relative to the entire entry structure).
Byte Index Byte Field Name
8–9 pktStatus
10–11 nextIndex
12–(7+n) RXData
The entry is updated as follows:
• The nextIndex field is updated as new bytes are written to the buffer.
• While a packet is being received, pktStatus.bEntryOpen is set to 1 by the radio CPU.
When an entry element is finished, either because the packet ended or because the element reached the
end of the entry, pktStatus.bEntryOpen is set to 0 by the radio CPU, and pktStatus.numElements is
incremented. If the packet continues in the next entry, pktStatus.bLastCont is set to 1 by the radio CPU. In
this case, the pktStatus.bFirstCont bit of the next entry is also set to 1 by the radio CPU. If no next entry is
available, the status is set to Unfinished, otherwise it is set to Finished.
The length field specified in the beginning of an entry element (depending on config.lenSz) gives the
length of that entry element within the entry, not the entire packet. If the length is not known when the
entry is opened, the length field is written to the remaining length of the entry and updated by the radio
CPU before the entry is finished.
For a partial read Rx entry, the radio CPU generates an Rx_Data_Written interrupt to the system CPU
whenever one or more bytes are written to the entry. In addition, it generates an Rx_N_Data_Written
interrupt when k bytes have been written since the last interrupt or the start of the entry element, where k
is given by config.irqIntv.
1488
Radio
Table 23-10
Table 23-13. Fields in a Partial Read RX Entry
Bits Bit Field Name Type
0–12 numElements
13 bEntryOpen
14 bFirstCont
15 bLastCont
Copyright © 2015, Texas Instruments Incorporated
is used. As for the multielement entry,
Description
Number of entry elements
R
committed in the entry
The entry contains an element that
R
is still open for appending data.
The first element is a continuation
R of the last packet from the previous
entry.
The packet in the last element
R
continues in the next entry.
Index to the byte after the last byte
R of the last entry element committed
by the radio CPU
Data received. Exact format
depends on operation being run.
R
Each entry element may start with
a length byte or word.
SWCU117C – February 2015 – Revised September 2015
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