The analog subsystem module is described in this section.
The analog modules on this device include the
Analog-to-Digital Converter (ADC), temperature sensor, Comparator Subsystem (CMPSS),
Programmable Gain Amplifier (PGA), and buffered Digital-to-Analog Converter
(DAC).
The analog subsystem has the following features:
- Flexible voltage references
- The ADCs have 3 reference options:
- Internal
Reference: In this mode the high reference voltage is generated
on-chip and brought to the VREFHI pin for capacitive
buffering. The VREFLO pin acts as the low side
reference and is normally connected to VSSA. There is an option
through a HW register bit to configure the ADC range as either
2.5V or 3.3V.
- External Reference: In this mode the high reference voltage is
supplied to the device from the VREFHI pin from an
external source. The VREFLO pin acts as the low side
reference and is normally connected to VSSA. There is an option
through a HW register bit to configure the ADC range as either
1x VREFHI or 2x VREFHI.
- VDDA/VSSA
Reference: In this mode the high and low references are sourced
from the VDDA/VSSA analog power supplies. If all ADCs are using
this mode the VREFHI/VREFLOpins can be
used as ADC input channels according to the analog pin signal
descriptions
- The buffered DAC is referenced to
VREFHI and VSSA. At least one ADC must be using either
the internal reference or external reference mode for the DAC to operate
correctly.
- The comparator DACs are referenced to VDDA and
VSSA.
- Flexible pin usage
- Buffered DAC outputs,
comparator subsystem inputs, and digital inputs (AIOs)/outputs (AGPIOs)
are multiplexed with ADC inputs
- Internal connection to
VREFLO on all ADCs for offset self-calibration