Multiple analog inputs ?

[Acetronics2]

Hi,

IF you want "real same time" measurements ... simply use :

1) slow variatons : RC Low pass on ADC inputs to filter and "damp" a bit

2) quick variations : External LF398 ( i.e.) Sample and Hold circuits ...

3) Use two external ADCs

4) Use a differential OPA ...


And then use the ADC ... or read the ext ADCs.

remember The Pic can do ONE THING ONLY at a time .... but can drive many peripherals at the same time ....

Alain

[rngd]

Hi,

IF you want "real same time" measurements ... simply use :

1) slow variatons : RC Low pass on ADC inputs to filter and "damp" a bit

2) quick variations : External LF398 ( i.e.) Sample and Hold circuits ...

3) Use two external ADCs

4) Use a differential OPA ...


And then use the ADC ... or read the ext ADCs.

remember The Pic can do ONE THING ONLY at a time .... but can drive many peripherals at the same time ....

Alain

Thanks Alain, but I dont think I need 'same time' measurements.

OK, so I have read the links. If my code is like this

pair1:

adcin 0, adc1 'read channel 0 to adc1
adcin 1, adc2 'read channel 1 to adc2
diff = abs(adc1-adc2)
if diff>tolerance then
' run servo1 for x seconds
goto pair1 'recheck values
else
return
endif

meaning I repeatedly check the analog input until 'diff' is less than 'tolerance', there will be no problems as I have

DEFINE ADC_SAMPLEUS 50

at the top, and this will add the delay between each ADCIN automatically. Am I correct ? Just want to confirm.

ps. I also read that sampling at 8 bits instead of 10 will improve the speed and stability when using multiple analog inputs. Will reducing to 8 bits help a lot, or can it work just fine with 10 bits ?