Pin and SPI Connection
The module has following pins connecting to a microcontroller:
CE: Chip (RX/TX) Enable, highly active. If high, module is either sending or listening.
CSN: Chip Select Not, low active. If low, the chip responds to SPI commands. This is actually the ‘real’ chip select signal and is easily confusing with CE which enables/disables the transceiver radio part.
SCK: SPI Shift Clock, up to 10 MHz.
MOSI: Master-Out-Slave-In, used to shift data from the microcontroller to the device.
MISO: Master-In-Slave-Out, used to shift data from the device to the microcontroller.
IRQ: Optional Interrupt Request pin. Signals RX/TX status like packet sent or received.