The following scenes are more suitable for using patterns 1 to pattern 3:
In some applications, the content transmitted by TX varies greatly, that is, the content of each sending,
the packet length and the number of packages are all uncertain. In this case, when the detection condition is
satisfied and the RX T1 is stopped, the switching rights of the RX is returned to the MCU, and it is better for
MCU to decide how long it will take to receive.
The following is the comparison of the 3 conditions:
The detection condition for option 1 is that RSSI_VLD is the output result of channel sensing. As
described earlier, channel sensing with the aid of PJD, can make a very fast and reliable decision about
whether a useful signal is present. More importantly, it does not need to be limited by the data format; it does
not need TX to send the long Preamble, and so on. Therefore, the advantage of option 1 is that when the RX
T1 window is set to a small size (for example, 5-8 symbols), it can still detect and judge very reliably.
The detection condition for option 2 is that PREAM_OK is the interrupt generated by Packet. This is a
traditional detection condition. Generally, at least 2 bytes or more Preamble lengths are required to ensure
that the detection is reliable. So the advantage is easy to understand, the disadvantage is there is the
Preamble inside the packet format, and the Preamble length transmitted by TX must be long enough
(covering 2 RX T1 and 1 SLEEP time). RX T1 also needs to cover 2 bytes or even longer Preamble to achieve
the reliable detection.
The detection conditions for option 3 are both valid at the same time. This means that the detection
conditions are relatively harsh, very difficult to be triggered by mistake. It is with very high reliability. The
minimum value of RX_PREAM_SIZE for CMT2300A can be set to 4 symbols. If combined with the RSSI_VLD
signal, it will not increase the time of RX T1, but also can achieve the more reliable detection result.
2.4.3 SLP Pattern 4
When the pattern is set to 4, RX T1 will stop the timer as long as RSSI_VLD is detected to be valid within
RX T1, and is always in RX until RSSI_VLD is invalid, and then automatically exits from RX. If RSSI_VLD is
detected to be invalid within RX T1, it will exit from RX after the timer is over.
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