-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf
Of Carl Denk
Sent: Tuesday, November 07, 2006 8:09 AM
To: piclist@mit.edu
Subject: [PIC] - ADC Sensor range adjustment?


I have a 18F1320 that will have 2 pressure sensor (Motorola Freescale 
MPX5010G and MPX5700GP) inputs. Both are 0 -5 volt (nominal) outputs. 
Planning the recommended filter caps and then to ADC ports. I don't need 
extreme accuracy, +/- 5% is OK. The sensors will plug in and 
interchangeable with several spares, along with the PIC boards so if a 
component goes bad, one needs to only swap out the sensor or board. With 
this interchangeability, should I include a POT  in the circuit for 
adjustment, and if so where should it be, series with the sensor output 
AND ADC INPUT?
>>
No pot needed.
you need to setup calibration routine to read minimum and maximum then
store the value in on board eeprom then read back on start up. you only
need to do this once.
<<


Also have a 10K ohm NTC Thermistor that will have a series resistor to 
an ADC input for temperature sensing. To be within a degree or so at 
freezing is needed, but the within a couple of degrees is adequate at 
other temps. Probably I can select the series resistors so they are 
close to each other for the spare boards, should I also plan a POT here?
>>
No Again.
Do same thing for this too
<<

In both cases, I plan to have one program with experimentally selected 
scaling factors to provide the actual values, and not tailor each spare 
board.
>>
sounds good
<<

Andre



Thanks :)
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