5.2.2 MVIO
The Multi-Voltage I/O (MVIO) is a feature from specific PIC18F and PIC32CM MCUs that allows a subset of I/O pins to operate at a different voltage domain than the rest of the device. This hardware-level integration eliminates the need for external level shifters when the MCU must communicate with peripherals operating at different logic levels, such as a 1.8V sensor connected to a 5V system. Table 5-10 provides a comparison of features between PIC18F and PIC32CM.
| Features | PIC18F MVIO | PIC32 MVIO |
|---|---|---|
| Integration | Stand-alone MVIO peripheral | Integrated into the Supply Controller (SUPC) |
| Primary Voltage Domain | VDD (main CPU and most I/O) | VDD (main CPU and VDDIO domain) |
| MVIO Voltage Domain | VDDIO2 (specific ports) | VDDIO2 (specific pins) |
| Operating Modes |
Standard operation: 1.62V–5.5V Low-Voltage operation: 0.95V–1.62V (specific devices) |
Dual Supply mode (independent VDD and VDDIO2) Single Power Supply mode (supply monitors turned off to save power) |
| Monitoring and Status | Status bit indicates the supply stability | Status (OK) bit and Low-Power POR bit |
| Interrupt Support | Interrupt on VDDIOxRDY or VDDIOxLVD (specific devices) | Interrupt on VDDIO2OK or Low-Power POR events |
| Power Sequencing | VDDIOx supply can ramp up and down independently of the VDD supply | Tri-states pins on power loss; reloads PORT configurations if VDDIO2 returns |
| Unique Features | Dual independent input buffers | Event System Integration: Can generate events based on the MVIO status |