RFM22 Datasheet, PDF (85/150 Pages) –

RFM22
Register 0Bh. GPIO Configuration 0
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
gpiodrv0[1:0]
pup0
gpio0[4:0]
Type
R/w
R/w
R/w
Reset value = 00000000
Bit
Name
Function
7:6
gpiodrv0[1:0] GPIO Driving Capability Setting.
Pullup Resistor Enable on GPIO0.
5
pup0
When set to 1 the a 200 KΩ resistor is connected internally between VDD and
the pin if the GPIO is configured as a digital input.
GPIO0 pin Function Select.
00000: Power-On-Reset (output)
00001: Wake-Up Timer: 1 when WUT has expired (output)
00010: Low Battery Detect: 1 when battery is below threshold setting (output)
00011: Direct Digital Input
00100: External Interrupt, falling edge (input)
00101: External Interrupt, rising edge (input)
00110: External Interrupt, state change (input)
00111: ADC Analog Input
01000: Reserved (Analog Test N Input)
01001: Reserved (Analog Test P Input)
01010: Direct Digital Output
01011: Reserved (Digital Test Output)
01100: Reserved (Analog Test N Output)
01101: Reserved (Analog Test P Output)
01110: Reference Voltage (output)
4:0
gpio0[4:0]
01111: TX/RX Data CLK output to be used in conjunction with TX/RX Data pin (output)
10000: TX Data input for direct modulation (input)
10001: External Retransmission Request (input)
10010: TX State (output)
10011: TX FIFO Almost Full (output)
10100: RX Data (output)
10101: RX State (output)
10110: RX FIFO Almost Full (output)
10111: Antenna 1 Switch used for antenna diversity (output)
11000: Antenna 2 Switch used for antenna diversity (output)
11001: Valid Preamble Detected (output)
11010: Invalid Preamble Detected (output)
11011: Sync Word Detected (output)
11100: Clear Channel Assessment (output)
11101: VDD
else : GND
85
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