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Receive Mode
Software is responsible for allocating table entries and for making sure that active short and extended
address entries do not overlap. There are separate enable bits for short and extended addresses:
• Short address entries are enabled in the SRCSHORTEN0, SRCSHORTEN1, and SRCSHORTEN2 registers.
Register bit n corresponds to short address entry n.
• Extended address entries are enabled in the SRCEXTEN0, SRCEXTEN1, and SRCEXTEN2 registers. In
this case, register bit 2n corresponds to extended address entry n. This mapping is convenient when
creating a combined bit vector (of short and extended enable bits) to find unused entries. Moreover,
when read, register bit 2n + 1 always has the same value as register bit 2n, because an extended
address occupies the same memory as two short-address entries.
Matching Algorithm
The SRCMATCH.SRC_MATCH_EN bit controls whether source address matching is enabled or not. When
enabled (which is the default setting) and a frame passes the filtering algorithm, the radio applies one of
the algorithms outlined in Figure 23-15, depending on which type of source address is present.
The result is reported in two different forms:
• A 24-bit vector called SRCRESMASK contains a 1 for each enabled short entry with a match, or two
1s for each enabled extended entry with a match (the bit mapping is the same as for the
address-enable registers on read access).
• A 7-bit value called SRCRESINDEX:
– When no source address is present in the received frame, or there is no match on the received
source address:
• Bits 6:0: 011 1111
– If there is a match on the received source address:
• Bits 4:0: The index of the first entry (i.e., the one with the lowest index number) with a match,
0–23 for short addresses or 0–11 for extended addresses.
• Bit 5: 0 if the match is on a short address, 1 if the match is on an extended address
• Bit 6: The result of the AUTOPEND function
Short Source Address (Mode 2) Extended Source Address (Mode 3)
The received source PAN ID is called srcPanid. The received short The received extended address is called srcExt.
address is called srcShort.
SRCRESMASK = 0x000000; SRCRESMASK = 0x000000;
SRCRESINDEX = 0x3F; SRCRESINDEX = 0x3F;
for (n = 0; n < 24; n++) { for (n = 0; n < 12; n++) {
bitVector = 0x000001 << n; bitVector = 0x000003 << (2*n);
if (SRCSHORTEN & bitVector) { if (SRCEXTEN & bitVector) {
if ((panid[n] == srcPanid) && if (ext[n] == srxExt) {
(short[n] == srcShort)) { SRCRESMASK |= bitVector;
SRCRESMASK |= bitVector; if (SRCRESINDEX == 0x3F) {
if (SRCRESINDEX == 0x3F) { SRCRESINDEX = n | 0x20;
SRCRESINDEX = n; }
} }
} }
} }
}
Figure 23-13. Matching Algorithm for Short and Extended Addresses
SRCRESMASK and SRCRESINDEX are written to RF Core memory as soon as the result is available.
SRCRESINDEX is also appended to received frames if the FRMCTRL0.AUTOCRC and
FRMCTRL0.APPEND_DATA_MODE bits have been set. The value then replaces the 7-bit correlation value
of the 16-bit status word.
Interrupts
239
SWRU191C–April 2009–Revised January 2012 CC253x Radio
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