RFM22B/23B
be modulated and transmitted. In RX mode it will be the received demodulated data. Figure 15 demonstrates using
SDI and SDO as the TX/RX data and clock:
TX on
command
TXoff
command
RX on
command
RX off
command
TX mode
RX mode
nSEL
SPI input
don’t care
don’t care
SPI input
MOD input
SPI input
don’t care
don’t care
SPI input
Data output
SPI input
SDI
Data CLK
Output
Data CLK
Output
SPI output
SPI output
SPI output
SPI output
SPI output
SDO
Figure 15. Microcontroller Connections
If the SDO pin is not used for data clock then it may be programmed to be the interrupt function (nIRQ) by
programming Reg 0Eh bit 3.
4.2.3. PN9 Mode
In this mode the TX Data is generated internally using a pseudorandom (PN9 sequence) bit generator. The primary
purpose of this mode is for use as a test mode to observe the modulated spectrum without having to provide data.
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