RFM22
VCC
GND
S
S
+1.8 to +3.6 V supply voltage. The recommended VCC supply voltage is +3.3 V.
Ground reference.
GPIO_0
I/O
General Purpose Digital I/O that may be configured through the registers to perform various
functions including: Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low
Battery Detect, TRSW, AntDiversity control, etc. See the SPI GPIO Configuration Registers,
Address 0Bh, 0Ch, and 0Dh for more information.
GPIO_1
GPIO_2
I/O
I/O
0–VCC V digital output that provides a serial readback function of the internal control
registers.
SDO
SDI
O
I
Serial Data input. 0–VCC V digital input. This pin provides the serial data stream for the 4-line
serial data bus.
Serial Clock input. 0–VDD V digital input. This pin provides the serial data clock function for
the 4-line serial data bus. Data is clocked into the RFM22 on positive edge transitions.
Serial Interface Select input. 0– VCC V digital input. This pin provides the Select/Enable
function for the 4-line serial data bus. The signal is also used to signify burst read/write mode.
General Microcontroller Interrupt Status output. When the RFM22 exhibits anyone of the
Interrupt Events the nIRQ pin will be set low=0. Please see the Control Logic registers
section for more information on the Interrupt Events. The Microcontroller can then determine
the state of the interrupt by reading a corresponding SPI Interrupt Status Registers, Address
03h and 04h.
SCLK
nSEL
I
I
nIRQ
O
I
Shutdown input pin. 0–VCC V digital input. SDN should be = 0 in all modes except Shutdown
mode. When SDN =1 the chip will be completely shutdown and the contents of the registers
will be lost.
SDN
I
I
Tx Antenna select input pin, When RFM22 is TX state,TX_ANT should be = 1, RX_ANT
should be = 0
TX_ANT
Rx Antenna select input pin, When RFM22 is RX state,RX_ANT should be = 1, TX_ANT
should be = 0
RX_ANT
ANT
I/O
RF signal output/input.(50 OHM output /input Impedance)
142
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