Kevin,

How about 5V / 1024 steps == about 4.88 mV / step
You have a count of 145 * 4.88 mV == .7076 V
A little closer?

Bill

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of kben@DCA.NET
Sent: Monday, February 16, 2004 4:12 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC:] 12F675 AD Resolution ?


Hi,

I am using a 12F675 to read a LM34DZ Temp Sensor.
If I read the sensor with my DMM I get 0.719
I calculate the reading I should get from the
pic as,  1024/5V = 204.8
204.8 * .719 = 147.25.
When I read the A/D from the pic I get 145.
So, I am off by 2.25. Is this an acceptable error ?

The LM34DZ is a high precision temp sensor of
the range 32F to 212F, outputting 10mv/Degree F.
I am powering the PIC with 5V from a bench supply
and have ample decoupling caps. I am using Vref as
the reference voltage.
How would I calculate the acceptable bit error ?

Thanks in advance,
               Kevin

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads