ok, i looked in the user guide again, and changed Vref from 1.223 to 0.6.
also i am getting the readings for temperature in kelvin which im converting to centigrade.
i am using the formula in the MPRMIBUserGuide (pg 18).
now the readings im getting are:
Volts Therm Adc2 Adc3 Adc4 Adc5 Adc6 Adc7
02.4675 27.1339 00317 00221 00204 00206 00204 00205
02.4675 27.1339 00304 00217 00202 00201 00201 00199
02.4675 27.2322 00305 00218 00202 00204 00201 00201
02.4774 27.2322 00303 00217 00206 00203 00202 00202
02.4774 27.1339 00306 00218 00202 00202 00202 00202
02.4774 27.2322 00307 00218 00202 00202 00204 00202
02.4675 27.1339 00303 00217 00206 00203 00202 00202
can u please tell me if im doing the conversin right, for the MSB and LSB to decimal?
should it be the other way round?
as far as i know the 2nd byte in the packet is the MSB, but it would be good to be sure.
also, the battery voltage is very low, but the battery is new, so what am i doing wrong out there?
thanks,
karan
On Mon, 2004-08-23 at 10:44, karan wrote:
hi,
im using the XSensorMDA500 app in contrib/xbow/apps/ to measure the battery voltage and the temperature from a mica2dot.
im using a mica2 with TOSBase on the programming board to send the data from the mica2dot to the pc. on the pc i have modified Dump.java and Listen.java to display these readings.
following is the formula for measuring the voltage from the mica2. this is from the MPRMIBUserGuide. this is in my Listen.java.
Dump.getDPC is converting the data received in hex form from the mote to a decimal. i know that works correctly.
double vbatt, vref=1.223, adc_fs=1024, adc_count;does adc_count have to be in hex??
adc_count = Dump.getDPC(System.out, packet, 9, 2); // volts 4,5
vbatt = vref * adc_fs / adc_count;
i am using the packet[i+1] byte as the MSB and packet[i[ byte as the LSB, is that correct?
so in the first line the thermistor data in hex is 01FB which is converted to dec as 507.
the values im getting from a new 3V Panasonic CR 2354 battery are:
Volts Therm Adc2 Adc3 Adc4 Adc5 Adc6 Adc7
F1 00 FB 01 3A 01 DE 00 CC 00 CC 00 CB 00 CC 00
5.19648 00507 00314 00222 00204 00204 00203 00204
F2 00 FB 01 3D 01 DF 00 CE 00 D0 00 CC 00 CC 00
5.17501 00507 00317 00223 00206 00208 00204 00204
F1 00 FB 01 3D 01 DF 00 CE 00 CD 00 CC 00 CD 00
5.19648 00507 00317 00223 00206 00205 00204 00205
F2 00 FC 01 39 01 DA 00 CB 00 CB 00 CA 00 CB 00
5.17501 00508 00313 00218 00203 00203 00202 00203
F1 00 FB 01 3D 01 DF 00 CE 00 CD 00 CF 00 CD 00
5.19648 00507 00317 00223 00206 00205 00207 00205
F2 00 FB 01 3D 01 DF 00 CE 00 CD 00 CC 00 CF 00
5.17501 00507 00317 00223 00206 00205 00204 00207
F2 00 FB 01 36 01 DC 00 CC 00 CC 00 CB 00 CC 00
5.17501 00507 00310 00220 00204 00204 00203 00204
F2 00 FB 01 3D 01 DF 00 CE 00 CD 00 CC 00 CF 00
5.17501 00507 00317 00223 00206 00205 00204 00207
Also how do i convert the thermistor reading into Celsius??
I looked for the xsensordot2 app, but its an empty directory.
what is the unit of the reading that im getting?
thanks in advance.
karan
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