Hi Alex,
The MSP430 microcontroller on the telosb mote has only two internal voltage references: 1.5 V and 2.5 V. You can't directly measure an input voltage that's greater than your reference voltage. What are you trying to measure? If it's your battery voltage, the MSP430 has an internal ADC channel that measures VCC/2 using a voltage divider <http://en.wikipedia.org/wiki/Voltage_divider> . In TinyOS, you can use the VoltageC component to access it, or you can have a look at the Msp430InternalVoltage components to see how it's done. If you're trying to measure something else that's outside the range of your reference voltage, you can use an external voltage divider. Hope this helps, Michiel From: [email protected] [mailto:[email protected]] On Behalf Of Alex FP Sent: woensdag 11 april 2012 22:00 To: [email protected] Subject: [Tinyos-help] Error marging using REFVOLT_LEVEL_2_5 to read a portADC Dear all. How can I indicate the Vref = 3.0V in a mote telosb? I have configured the mote with this: REFERENCE_VREFplus_AVss, REFVOLT_LEVEL_2_5, ... Is not possible configure it with something similar to REFVOLT_LEVEL_3_0, So when my pair of batteries (AA) is not fully charged, with a value between both of 2.5 V, I got the correct input value from the ADC0 pin, aproximately 450 (in decimal) But when I'm using two new batteries I got a value with a considerable error, i.e. 590 (in decimal). Please someone could give me an advice about the manner to fix it? Thanks in advance. Regards, Alex.
_______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
