The VeREF+ is connected to ground as well. I think theres no way to convert negative voltage with ADC channel.
-Yicheng _____ From: Juan Antonio López Riquelme [mailto:[EMAIL PROTECTED] Sent: Tuesday, May 01, 2007 7:51 AM To: Oussama Chougna Cc: yicheng; tinyos-help@millennium.berkeley.edu Subject: Re: [Tinyos-help] can Tmote sky ADC port be used to measure negativevoltage Hi, thank you, i not see this pins before, i only see .h file and i believe that tmote can use reference negative, i am sorry. If you see the schematic, VeREF+ is connect to ADC0 in expansion connector, maybe if you provides negativa power in ADC0 line you can convert values from -power to 0, buy you also need positive values, i believe that is more easy scaling to positive values the output of you device before of connect to tmote. A greeting, Juan Antonio. 2007/5/1, Oussama Chougna <[EMAIL PROTECTED]>: 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; tinyos-help@millennium.berkeley.edu 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] <mailto:[EMAIL PROTECTED]> ] On Behalf Of yicheng Sent: woensdag 25 april 2007 20:53 To: tinyos-help@Millennium.Berkeley.EDU 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 Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
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