Rx Automatic Frequency Hopping (Rx Auto Hop) - CMOSTEK CMT2310A Manual

CMT2310A
The T1 and T2 mentioned in the table above refer to the RX T1 and the RX T2 time interval that can be set via the registers or
RFPDK.The source of RSSI_VLD can be the comparison result of the RSSI or the detection result of the phase jump detector
(PJD).

7.3 Rx Automatic Frequency Hopping (RX AUTO HOP)

When the chip enters a channel for receiving, if no successful events are detected in the corresponding mode, the chip will return
to READY or RFS state according to FREQ_SW_STATE, then automatically configure the channel value in the next byte in the
hopping table then re-enter Rx state for receiving. If the automatic switched state is READY, the PLL frequency will be
re-calibrated before re-entering RX with corresponding calibration time consumed; if the automatic switched state is RFS, the
PLL frequency will not be re-calibrated, thus the switching time is shorter. If the interval between any two frequency points in the
frequency hopping table exceeds 2MHz, it is recommended to configure FREQ_SW_STATE to the READY state, for it is
necessary to recalibrate the PLL in this case.
If successful events are detected, the chip will auto-hop and wait for the further processing from the external MCU or switch to the
pre-configured state. If successful events are detected when the entire table hopping is finished, the chip will hop from the start of
the table if RX_HOP_PERSIST is configured as 1, or else return to the state specified in RX_EXIT_STATE if RX_HOP_PERSIST
is configured as 0 to finish the Rx-auto-hopping operation. The destination frequency point calculation is as follows.
FREQ = 1K x FREQ_SPACE<7:0> x FREQ_CHANL<7:0>
In the calculation above, FREQ_SPACE<7:0> is an independent register, FREQ_CHANL<7:0> is configured through 64
registers with each one stores a single channel value.
The register REQ_CHANL_LV of RX_Auto_Hop mode lets users know which channel currently is used. Moreover, the register
FREQ_DONE_TIMES is to let users read the number of currently finished hopping.
The RX_Auto_Hop mode needs to use RX T1 TIMER and RX T2 TIMER, therefore TIMER_RX_EN must be set to 1. RX T1
TIMER is configured through TIMER_M_RX_T1 and TIMER_R_RX_T1 and the actual timer time is calculated according to the
timer formula. RX T2 TIMER is configured through TIMER_M_RX_T2 and TIMER_R_RX_T2 and the actual timer time is
calculated according to the formula.
CCA_INT_SEL is used to determine whether RSSI_PJD_VLD is judged through RSSI or PJD; RX_EXIT_STATE is used to
determine which state to be returned to when it exits Rx; PKT_DONE_EXIT_EN is used to determine when receiving PKT_DONE
whether it will exit Rx and return to the state configured by RX_EXIT_STATE or keep in the current state.
After having configurations done, users can set RX_AUTO_HOP_EN to 1 to enable the function, then send command go_rx to
enter the RX_Auto_Hop mode. During the auto-operation, if events triggering the stop of the auto-operation occur, the chip will
stop the auto-operation and stay in some fixed state. If requiring to stop the RX_Auto_Hop operation, users can set API_STOP to
1. When the chip detects this bit being set, it will set API_DONE_FLAG to 1 upon the next state switching, then keep the current
configurations, exit the RX_Auto_Hop function and return to READY state.
After the halt of RX Auto Hop, if RX_AUTO_HOP_EN is kept as 1, the chip will enter Rx-auto-hopping operation again once users
send go_rx command again, and it will start hopping from the next frequency point since the latest finished hopped frequency
point. If users wanted start hopping from the first frequency point, they can clear register FREQ_DONE_TIMES before sending
go_rx command.
The Rx-Auto-Hop supports the following 7 operating modes.
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