5.2.2 MVIO
Multi-Voltage I/O (MVIO) is a feature available on specific AVR and PIC32CM MCUs that allows a subset of I/O pins to operate in a different voltage domain from 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 5-11 shows a comparison of MVIO features between AVR and PIC32CM.
| Feature | AVR® MVIO | PIC32CM 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 | Dual Supply mode: Independent VDD and VDDIO2 |
Dual Supply mode (independent) Single Power Supply mode (supply monitors turned off to save power) |
| Monitoring and Status | Status bit indicates if the voltage is in range | Status (OK) bit and Low-Power POR bit |
| Interrupt Support | Interrupt on VDDIO2 status change | Interrupt on VDDIO2OK or Low-Power POR events |
| Power Sequencing | Tri-states MVIO pins if VDDIO2 is below the acceptable range | Tri-states pins on power loss; reloads PORT configurations if VDDIO2 returns |
| Unique Features | Schmitt trigger levels are automatically scaled according to VDDIO2 | Event System Integration: Can generate events based on the MVIO status |