When external voltage references are used, the comparator module can be configured to have the comparators operate from the same or different reference sources before engineer can carry out the Extract Code from Secured MCU dsPIC30F6014A operation. However, threshold detector applications may require the same reference.
The reference signal must be between VSS and VDD and can be applied to either pin of the comparator(s).The comparator module also allows the selection of an internally generated voltage reference from the
comparator voltage reference module. This module is described in more detail in Section 21.0 “Comparator
Voltage Reference Module”.
The internal reference is only available in the mode where four inputs are multiplexed to two comparators (CM2:CM0 = 110). In this mode, the internal voltage reference is applied to the VIN+ pin of both comparators.
Response time is the minimum time, after selecting a new reference voltage or input source, before the comparator output has a valid level. If the internal reference is changed, the maximum delay of the internal voltage reference must be considered when using the comparator outputs. Otherwise, the maximum delay of the comparators should be used (see Section 26.0 “Electrical Characteristics”).
The comparator outputs are read through the CMCON register. These bits are read-only. The comparator outputs may also be directly output to the RA4 and RA5 I/O pins. When enabled, multiplexors in the output path of the RA4 and RA5 pins will switch and the output of each pin will be the unsynchronized output of the comparator in order to Extract Code from Secured MCU dsPIC30F6014A. The uncertainty of each of the comparators is related to the input offset voltage and the response time given in the specifications.
The TRISA bits will still function as an output enable/disable for the RA4 and RA5 pins while in this mode. The polarity of the comparator outputs can be changed using the C2INV and C1INV bits (CMCON<4:5>). Note 1: When reading the Port register, all pins configured as analog inputs will read as a ‘0’. Pins configured as digital inputs will convert an analog input according to the Schmitt Trigger input specification. 2: Analog levels on any pin defined as a digital input may cause the input buffer to consume more current than is specified.
