If you read in the MSP430x161x data sheet, in the section "12-bit ADC, external reference", the minimum allowable voltage into VeREF- is 0V.
Cheers, Cory On 5/1/07, Oussama Chougna <[EMAIL PROTECTED]> wrote:
Antonio, The settings for an ADC port are defined in MSP430ADC12.h header file. As the negative reference voltage you can specify VeRef-, but in the TMote Sky datasheet schematics you can clearly see that the VeRef- pin of the MSP430 is soldered to ground. It is moteiv's design and too bad. So programming will take no effect on this. Ground stays zero, so you cannot do conversions between -2,5V and 2,5V. But you can between 0 and 2,5V. Greeting, oussama ------------------------------ *From:* Juan Antonio López Riquelme [mailto:[EMAIL PROTECTED] *Sent:* dinsdag 1 mei 2007 13:16 *To:* Oussama Chougna *Cc:* yicheng; [email protected] *Subject:* Re: [Tinyos-help] can Tmote sky ADC port be used to measure negativevoltage Hi Yicheng and Oussama, if you read TEP101 (appendix A) then you can know that the conversion reference is programable. For use ADC i supose that you use a components in the folder C:\cygwin\opt\tinyos-2.x\tos\chips\msp430\sensors of template and modify the fields of struct for use an ADC of expansion port. You also can change values of fields two (sref) and three (ref2_5v) with the options that appear below in the same file (C:\cygwin\opt\tinyos- 2.x\tos\chips\msp430\adc12\Msp430Adc12.h ). A greeting, Juan Antonio. 2007/5/1, Oussama Chougna <[EMAIL PROTECTED]>: Hi, I have this problem too. If you check the schematics in the TMote Sky datasheet, you will see that the negative reference voltage pin is grounded. So you can measure only between 0 and any value. oussama ------------------------------ *From:* [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] *On Behalf Of *yicheng *Sent:* woensdag 25 april 2007 20:53 *To:* [email protected] *Subject: *[Tinyos-help] can Tmote sky ADC port be used to measure negativevoltage Hi, Just want to know if negative voltage (like -1.5v) can be measured by any Tmote sky ADC port? If yes, how can I do it? Do I need to set a negative reference voltage? Thanks! Yicheng _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
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