How much voltage can a XMEGA ADC measure?
Though this feature has its advantage in some certain areas it comes at a cost of reduced top range which about 95% of the reference source’s value. If, for example, the internal 1.0V reference is used then the ADC can measure voltages ranging from about -0.05V to about 0.95V.
Is the XMEGA ADC block in differential mode?
In the XMega ADC block this differential mode is technically the same stuff. You have two ADC pins as inputs in differential mode and an optional gain stage. Typically use of differential mode is that for measuring current flowing through a shunt. However a few things are to be strictly followed:
What is the clock speed of the XMEGA CPU?
First configure the XMega clock, then I/O port pins and finally the ADC itself. In all of my example codes the XMega CPU is configured to run at 8MHz clock speed and only PORTA pins are used for ADC inputs.
What is the ADC count in differential mode?
However a few things are to be strictly followed: Only signed conversion is possible in differential mode. Thus the 12bit ADC count has a range from -2048 to 2047, centering at 0. All pins can be positive inputs but only a few specified and be negative inputs.
What does Vout mean in XMEGA ADC block?
Simply Vout = m x ( Vinp – Vinn ), where m is the gain, Vinp is the positive input and Vinn is the negative input. In the XMega ADC block this differential mode is technically the same stuff. You have two ADC pins as inputs in differential mode and an optional gain stage.
What is the range of 12bit ADC pins?
Thus the 12bit ADC count has a range from -2048 to 2047, centering at 0. All pins can be positive inputs but only a few specified and be negative inputs. Only ADC0 – ADC3 pins can be negative input pins in differential mode without gain while only ADC4 – ADC7 pins can be negative input pins in differential mode with gain.
Can a 12 bit ADC measure negative voltage?
This offset should be compensated in the software end and in the process the ADC is no long a 12 bit ADC for general purpose uses. Owing to this offset the maximum value of voltage the ADC can measure is also below the reference voltage. However a tiny amount of negative voltage can be detected in this mode.