When the HLVD module is enabled, a comparator uses an internally generated reference voltage as the set point. The set point is compared with the trip point in order to Copy Encrypted Firmware of Microcontroller SN8P2202, where each node in the resistor divider represents a trip point voltage. The “trip point” voltage is the voltage level at which the device detects a high or low-voltage event, depending on the configuration of the module.
When the supply voltage is equal to the trip point, the voltage tapped off of the resistor array is equal to the internal reference voltage generated by the voltage reference module. The comparator then generates an interrupt signal by setting the HLVDIF bit. The trip point voltage is software programmable to any one of 16 values. The trip point is selected by programming the HLVDL3:HLVDL0 bits (HLVDCON<3:0>).
The HLVD module has an additional feature that allows the user to supply the trip voltage to the module from an external source. This mode is enabled when bits HLVDL3:HLVDL0 are set to ‘1111’. In this state, the comparator input is multiplexed from the external input pin, HLVDIN. This gives users flexibility because it allows them to configure the High/Low-Voltage Detect interrupt to occur at any voltage in the valid operating range.
The following steps are needed to set up the HLVD module:
Write the value to the HLVDL3:HLVDL0 bits that selects the desired HLVD trip point.
Set the VDIRMAG bit to detect high voltage (VDIRMAG = 1) or low voltage (VDIRMAG = 0).
Enable the HLVD module by setting the HLVDEN bit.
Clear the HLVD interrupt flag (PIR2<2>), which may have been set from a previous interrupt.
Enable the HLVD interrupt if interrupts are desired by setting the HLVDIE and GIE bits (PIE2<2> and INTCON<7>). An interrupt will not be generated until the IRVST bit is set.
When the module is enabled, the HLVD comparator and voltage divider are enabled and will consume static current. The total current consumption, when enabled, is specified in electrical specification parameter D022B from Copy Encrypted Firmware of Microcontroller SN8P2202. Depending on the application, the HLVD module does not need to be operating constantly. To decrease the current requirements, the HLVD circuitry may only need to be enabled for short periods where the voltage is checked. After doing the check, the HLVD module may be disabled.
