Texas Instruments CC112 Series, User Manual, Page: 55 / 109

CC112X/CC1175
SWRU295C Page 55 of 108
8.5 RX Termination
RX can be terminated by the use of an RX termination timer or based on the assertion of
CARRIER_SENSE
and/or
PQT_REACHED
. When RX terminates, the chip will always go back to IDLE if
eWOR is disabled and back to SLEEP (via IDLE) if eWOR is enabled.
8.5.1 RX Termination Timer
CC112X
has functionality to allow for automatic termination of RX after a programmable timeout. The
main use for this functionality is in eWOR mode, but it is also useful for other applications as it
reduces the need for a dedicated MCU timer. The termination timer starts when the chip has entered
RX state, and the timeout is programmable with the
RFEND_CFG1.RX_TIME
setting. When the timer
expires, the radio controller will check the condition for staying in RX.
The programmable conditions are:
RFEND_CFG1.RX_TIME_QUAL = 0
: Continue receive if sync word has been found
RFEND_CFG1.RX_TIME_QUAL = 1
: Continue receive if sync word has been found, or if PQT is
reached or CS is asserted
Equation 19 can be used to calculate the RX timeout.
XOSC
RES WOR
TIME RX
f
EVENT
FLOOR MAX
1250
2
2
0
, 1 Timeout RX
_ 4
3 _
Equation 19: RX Timeout
EVENT0 is programmed through
WOR_EVENT0_MSB
and
WOR_EVENT0_LSB
,
RX_TIME
is found in
RFEND_CFG1
and
WOR_RES
in
WOR_CFG1
.
Figure 22 shows how the radio stays in RX until a packet has been received since a sync word was
found before the RX termination timer expired (after 10 ms).
RX
Time [ms]
1 2 3 4 5
Preamble Sync Payload CRC
IDLE IDLE
14 15 16
RX_TIME_QUAL = 0
No sync found after 10 ms
RX
1 2 3 4 5
IDLE IDLE
14 15 16
RX_TIME_QUAL = 0
Sync found within 10 ms
17 18 19 20
Time [ms]
Figure 22: RX Termination when
RX_TIME_QUAL = 0
(RX Timeout = 10 ms)