Re: TI-H: pressure sensor

To: ti-hardware@lists.ticalc.org
Subject: Re: TI-H: pressure sensor
From: "ryan pogge" <ryanpogge@hotmail.com>
Date: Sat, 31 Jan 1998 18:10:08 PST
Reply-To: ti-hardware@lists.ticalc.org

darn..
well thats what i was afraid of,  anyone interested in writeing pic or 
avr code for it?
it shouldent be THAT hard. all i have is a basic stamp :O.
of coarse the driver for the calc is prolly hard to make.
well it was just an idea, i thought maybee a combo pessure/temp sensor 
would be cool, maybee even humidity.

i was also thinking....could a TI-calc be made to store phone numbers 
and dial a phone? i was thinking since BSII have dtmf output that maybee 
the calc could use that to dial phones? any ideas...just another 
thought.

no i dont know alot about electronics. just a little. :)


>I don't know that particular chip at all, but it sounds like the 
voltage
>output on pin 3 is a function of the pressure applied to the case. The 
TI
>uses TTL logic (either 0 or 1, nothing in between), so the pressure 
sensor
>would not work if connected directly to the link port. An A/D
>(analog-to-digital) converter would be needed. They basically measure 
the
>voltage of an analog signal at a predetermined sampling rate and record
>that voltage as a digital number. So then you'd probably need a
>microcontroller to sample that information at some interval (like .5 s 
or
>so) and pass it through the link port to some asm program which would
>provide user interface and device control.
>
>
>On Sat, 31 Jan 1998, ryan pogge wrote:
>
>> I was wondering if we could make a pressure sensor for the 85(or any 
>> other calc for that matter.
>> 
>> I have a motorola mpx4100a presure sensor.
>> it looks like this.
>> 
>>     ____
>>    /    \          pin 1 is VCC 5 volts
>>   |  o   |         pin 2 is ground 
>>    \____/          pin 3 is Vout (betwean 0-5 volts)
>>    /||||\          pins 4-6 are not used
>>   | |||| |         
>>   1 2345 6
>> 
>> is it possible to have a assembly program sense the voltage  comeing 
>> into the link port? i dont know assembly so i would need some one to 
>> write the driver..but the pressure is related to Vout by an equation 
>> which you can find at along with the data sheet here:
>> http://mot2.indirect.com/cgi-bin/get?/books/dl200/pdf/mpx4100rev*.pdf
>
>-- 
>Greg Hill
>greg-hill@bigfoot.com
>www.comports.com/link
>
>
>


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