5.1.1. Analog Input Configuration
The analog multiplexer routes signals from external analog input pins, Port 3 I/O pins (See Section
“17.1.5. Configuring Port 1, 2, and 3 Pins as Analog Inputs” on page 207), a High Voltage Difference
Amplifier, and an on-chip temperature sensor as shown in Figure 5.2.
Figure 5.2. Analog Input Diagram
Analog signals may be input from four external analog input pins (AIN0.0 through AIN0.3) as differential or
single-ended measurements. Additionally, Port 3 I/O Port Pins may be configured to input analog signals.
Port 3 pins configured as analog inputs are selected using the Port Pin Selection register (AMX0PRT). Any
number of Port 3 pins may be selected simultaneously as inputs to the AMUX. Even numbered Port 3 pins
and odd numbered Port 3 pins are routed to separate AMUX inputs. (Note: Even port pins and odd port
pins that are simultaneously selected will be shorted together as “wired-OR”.) In this way, differential mea-
surements may be made when using the Port 3 pins (voltage difference between selected even and odd
Port 3 pins) as shown in Figure 5.2.
The High Voltage Difference Amplifier (HVDA) will accept analog input signals and reject up to 60 volts
common-mode for differential measurement of up to the reference voltage to the ADC (0 to VREF volts).
The output of the HVDA can be selected as an input to the ADC using the AMUX as any other channel is
selected for input. (See Section “5.2. High-Voltage Difference Amplifier” on page 52).