Dear all,
I'm using a soil sensor which have one wire to excite it, another that
returns a voltage to connect it to the ADC port in a datalogger.
I've connected the wire (Analog output) of the soil sensor to the 6 ports
available in the TelosB (in the 6-U28 and 10-U2 pin expansion.)
ADC0(P6.0), ADC1(P6.1), ADC2(P6.2), ADC3(P6.3), ADC6(P6.6), ADC7(P6.7) I
did a test independently, each one per time
The soil sensor was excited by the TelosB mote through its GIO(2) port,
and the TelosB is using AA batteries.
But I'm having fluctuating values as the next:
0.227704
0.220072
0.238728
0.240848
0.232368
0.24424
0.234064
0.233216
The above values has been trasnformed to m3/m3 to understand as Volumetric
Water Content (VWC)
All the values are in inside an acceptable range. But I don't know why
this values change a little every sampling? There is a way to fix this?
When the exciting wire of the sensor soil is connected to the AVCC port
that all time feeds soil sensor with 3V, the values maintains constant.
But the issue in this case is that the batterie discharge is very fast
because all time the soil sensor is consuming 2 mA.
This is the code respect the ADC ports.
const msp430adc12_channel_config_t EC_20 = {
INPUT_CHANNEL_A3,
REFERENCE_AVcc_AVss,
SAMPLE_HOLD_4_CYCLES,
SHT_SOURCE_SMCLK,
SHT_CLOCK_DIV_1,
SAMPCON_SOURCE_SMCLK,
SAMPCON_CLOCK_DIV_1,
REFVOLT_LEVEL_1_5
};
I'll appreciate all advices.
Yours faithfully,
Alejandro
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