Thinking of ADC in a PIC 18F micro.
I need to perform AD conversions of a single ended signal ranging between 2900 and 3700 mV. By design I know that it cannot escape from there.
To increase resolution I should bring those values down to the 0 - 800 mV range and reduce Vref as much as the micro allows (and as long it is equal or higher than 800 mV), always with -Vref to ground. For the moment, I cannot change the level of the input range, so I am left playing only with Vrefs.
Today, reading the manual of a micro, I realized the possibility of deciding on the +Vref and -Vref settings. I never had clear what is the use of -Vref
a) For my range 2900-3700 mV, would it make sense to set: +Vref =5,0V and -Vref =4,2V?
b) If the above is just stupid, could anyone at least give a concrete example of what's the use of -Vref? Kind of a grey area to me.
Gracias for any reply.
I need to perform AD conversions of a single ended signal ranging between 2900 and 3700 mV. By design I know that it cannot escape from there.
To increase resolution I should bring those values down to the 0 - 800 mV range and reduce Vref as much as the micro allows (and as long it is equal or higher than 800 mV), always with -Vref to ground. For the moment, I cannot change the level of the input range, so I am left playing only with Vrefs.
Today, reading the manual of a micro, I realized the possibility of deciding on the +Vref and -Vref settings. I never had clear what is the use of -Vref
a) For my range 2900-3700 mV, would it make sense to set: +Vref =5,0V and -Vref =4,2V?
b) If the above is just stupid, could anyone at least give a concrete example of what's the use of -Vref? Kind of a grey area to me.
Gracias for any reply.