RFM31 Datasheet, PDF (77/137 Pages) –

RFM31
Register 0Fh. ADC Configuration
Bit
Name
Type
D7
adcstart/
adcdone
R/w
D6
D5
D4
adcsel[2:0]
R/w
D3
D2
adcref[1:0]
R/w
D1
D0
adcgain[1:0]
R/w
Reset value = 00000000
Bit
Name
Function
adcstart/adcdone ADC Measurement Start Bit.
7
Reading this bit gives 1 if the ADC measurement cycle has been finished.
ADC Input Source Selection.
The internal 8-bit ADC input source can be selected as follows:
000: Internal Temperature Sensor
001: GPIO0, single-ended
010: GPIO1, single-ended
6:4
adcsel[2:0]
011: GPIO2, single-ended
100: GPIO0(+) – GPIO1(–), differential
101: GPIO1(+) – GPIO2(–), differential
110: GPIO0(+) – GPIO2(–), differential
111: GND
ADC Reference Voltage Selection.
The reference voltage of the internal 8-bit ADC can be selected as follows:
3:2
adcref[1:0] 0X: bandgap voltage (1.2 V)
10: VDD / 3
11: VDD / 2
ADC Sensor Amplifier Gain Selection.
The full scale range of the internal 8-bit ADC in differential mode (see adcsel)
1:0
adcgain[1:0] can be set as follows:
adcref[0] = 0: adcref[0] = 1:
FS = 0.014 x (adcgain[1:0] + 1) x VDD FS = 0.021 x (adcgain[1:0] + 1) x VDD
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