HT98R068-1 Two-way Radio OTP MCU
RX Mode
This mode is mainly applied for in-band signal demodulation. Although it is acceptable to
wait for the RF signal in this mode, it is recommended that the MCU should verify the
RSSI (Receive signal strength indicator) signal before switching the input source to the
DEMOD path and then enable the audio processor for management. In this way, power
can be saved and in the meantime avoid erroneous signal judgments. The modes
switching, paths selection, circuit ON/OFF and the SPI command settings are as follows:
Ex: RX mode, Input = DEMOD, Output = AUDO (source = DAC1), No Sub-tone.
RX Mode Setup Flow
Flow description:
<RSSI OK>: Confirm if the RF signal is OK.
<81E8B>: Enable the DAC1, buffer and PGA circuits. Setup the circuit switches first.
DAC1 on-enable DAC1 output, AUDO output buffer on- enable the audio output circuit,
PGA on- enable the PGA input source.
<81B25>: Select the PGA and audio input source paths. Select the PGA input source
to be DEMOD, the audio output to be DAC1 and then switch the DAC1 pin source path
to the internal common-mode bias voltage in order to prevent the audio leaking from
MOD.
<81160>: Enter the RX mode. Select the RX mode as the final step to enter the RX
processing flow.
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