Texas Instruments CC112 Series, User Manual, Page: 60 / 109

CC112X/CC1175
SWRU295C Page 60 of 108
8.6.2 eWOR Modes
The different eWOR modes are programmed through the
WOR_CFG1.WOR_MODE
register field. The
three most common eWOR modes are Feedback Mode, Normal Mode, and Legacy Mode.
Feedback Mode
The radio wakes up on Event 0 and strobes
SRX
on Event 1. If a good packet is being
received the radio enters the state indicated by the
RFEND_CFG1.RXOFF_MODE
setting.
When a bad packet is received (packet length/address/CRC error) the radio will either restart
RX or enter SLEEP mode, depending on
RFEND_CFG0.TERM_ON_BAD_PACKET_EN
. If
TERM_ON_BAD_PACKET_EN = 1
, the radio will go to IDLE instead of SLEEP after receiving
16 bad packets in a row
17
. When this occurs, a GPIO pin can be used to wake up the MCU by
setting
IOCFGx.GPIOx_CFG = MARC_MCU_WAKEUP
(20). Please see Section 3.4.1.2 for
more details on MARC MCU Wake-Up.
Normal Mode
This mode is equivalent to Feedback Mode without the bad packet counter feature. This
means that the radio can go back to SLEEP when a bad packet is received as long as
TERM_ON_BAD_PACKET_EN = 1
, but it does not give any feedback to the MCU regarding
this.
Legacy Mode
As long as a sync word has been received, the radio will not go back to SLEEP automatically.
If a good packet is being received the radio enters the state indicated by the
RFEND_CFG1.RXOFF_MODE
setting and when a bad packet is received it will either restart RX
or enter IDLE mode, depending on
RFEND_CFG0.TERM_ON_BAD_PACKET_EN
.
There are also two other modes using the eWOR timer as a general sleep timer or to generate timing
signals for the MCU.
Event 1 Mask Mode enables the radio to wake up from SLEEP on Event 0 without going to RX mode
while Event 0 Mask Mode keeps the radio in SLEEP mode ignoring all the events. In both cases the
WOR_EVENT0/1
signals can still be made available on the GPIO pins to be used by the MCU or other
peripherals in the system by setting
IOCFGx.GPIOx_CFG = WOR_EVENT0/1
(55/56).
8.6.3 eWOR Usage
eWOR can be used in systems where a transmitter sends a packet at a given interval (see Figure 26).
TX
Time
Time
TX TX
1 s 1 s
1 s 1 s
1 s
TX
1 s
Pr sync
Payload
RX RX RX RX
XOSC Start-Up
RX Timeout
Extra time in RX
to receive the packet
Figure 26: eWOR Mode (RX and TX in sync.)
Under ideal circumstances, the receiver and transmitter is in sync as shown in Figure 26, but in most
cases this is not the case. Assume the transmitter is sending packets at a slower rate than the
receiver wakes up to look for packet as shown in Figure 26.
17
To not receive a packet at all is in this content equivalent to receiving a bad packet