Help Read negative voltage

[gzorzi]

Can I read negative voltage with pic microcontroller ?
The voltage is between +/- 1V
Thanks

[mat janssen]

No, but you can put the input to 2 volts and add your input voltage. And in the programm you subtract the 2 volts. And now you know the real input voltage.

[mister_e]

Maybe 1 volt in addition to your input voltage in a summing amplifier based on op amp (741,lm324,op07,ne5532, or any else hanging on your bench) will be enough too ( 2 volt also).

0v output of op amp will mean -1v
1v output of op amp will mean 0v
2v output of op amp will mean +1v

will be easy to convert in a readable VAR with 2 IF THEN ELSE or 1 SELECT CASE with 2 branchs.

regards

[gzorzi]

OK thanks
If I want to use a radio remote controller what is it the best way ?

[Melanie]

There is another way (depending on available Power Supplies)... set Vss to a minus Voltage level (eg -1v) and set Vdd correspondingly 5v away from Vss.

I have a favourite AC switch called a ACS108 that I use... it's a dream for interfacing directly to a PIC... however, it needs a negaitive current on its trigger. Simple solution... connect the PIC's Vdd to 0v and have Vss set to -5v.

Never be afraid of the unconventional... the PIC might need 5v to work, but that 5v can be referenced anywhere in the universe.

Now, without knowing a lot more about your application, I can't say that this is the ideal solution here, it may not be... but what I am suggesting is that you can break out of conventional thinking to design a solution.

You may also want to do an internet search on "Level Shifters" which is what you basically need. Op-Amps and Opto-Isolators are the obvious choices... but an Op-amp may need a split Power Supply to handle negative going signals, and if you're going to do that, you might as well use a cheap PIC with ADC as "Electronic Glue" as I mentioned at the start of this posting.

Melanie

[mister_e]

If I want to use a radio remote controller what is it the best way ?

what you want to do exactly and wich controller. I can help.

regards.

[gzorzi]

Example TWS434. I haven't found picbasic program and schematics

[mister_e]

o.k. Depending of your transmitter you may need some decoder like holtek HT640,HT648L. You can also do it in software... for sure. For your purpose you will use SERIN,HSERIN command. Be sure of your transmitter baud rate too.

This may help you.
http://www.rentron.com/rf_remote_control.htm

ok it's in basic stamp language but... close to picbasic!!!

here's a few remote control project
http://www.rentron.com/remote.htm

say thanks to Bruce!!!

hope this help