Introduction

Authors: Johan Vaarlid, Microchip Technology Inc.

The AVR® DB Family of microcontrollers is equipped with a configurable integrated level shifter. The Multi-Voltage I/O (MVIO) feature allows a subset of the I/O pins to be powered by a different I/O voltage domain VDDIO2. The rest of the I/O pins runs on VDD. Both VDD and VDDIO2 have the same voltage range. Consult the Electrical Characteristics section of the data sheet for the exact voltage range. This eliminates the need of having external level shifters for communication or control of external components running on a different voltage level. Eliminating external logic level shifters will, in turn, reduce the BOM and free up PCB real estate.

Figure . Multi-Voltage I/O can Completely Replace External Logic Level Converters

This technical brief describes how the Multi-Voltage I/O feature works on the AVR DB Family of microcontrollers. It covers the following use cases:

  • Polling VDDIO2 Status:

    Checking if the VDDIO2 voltage is within the acceptable range by reading the Status bit.

  • Interrupt on VDDIO2 Status:

    Make use of the interrupt that occurs when the Status bit changes state.

  • Measuring VDDIO2:

    Use the internal ADC to measure the VDDIO2 voltage.

  • Blink a 3V LED with VDD at 1.8V:

    A basic example of MVIO blinking an LED with a forward voltage higher than VDD.

Note: The code examples were developed on AVR128DB48 Curiosity Nano (EV35L43A), and are available on GitHub.