Microchip Technology TB3287 Reference manual

TB3287
Getting Started with Multi-Voltage I/O (MVIO)
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 1. Multi-Voltage I/O can Completely Replace External Logic Level Converters
VDD
1.8-5.5V
VDD VDD VDDIO2
GND GND GND
GNDGND
VDDIO2
1.8-5.5V
Microcontroller
Logic
Level
Converter
Sensor
MVIO
Sensor
Sensor
Sensor
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:
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 1

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.
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© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 2

Table of Contents
Introduction.....................................................................................................................................................1
1. Relevant Devices.................................................................................................................................... 4
2. Overview................................................................................................................................................. 5
3. Hardware Configuration.......................................................................................................................... 7
3.1. Using the Curiosity Nano AVR128DB48...................................................................................... 7
3.2. Supplying Power To VDDIO2....................................................................................................... 7
4. Reading the Status Bit............................................................................................................................ 9
5. Interrupt on VDDIO2 Status ................................................................................................................. 10
6. Measuring VDDIO2............................................................................................................................... 11
7. Blinking a 3V LED with VDD at 1.8V.....................................................................................................15
8. References............................................................................................................................................17
9. Revision History.................................................................................................................................... 18
10. Appendix............................................................................................................................................... 19
The Microchip Website.................................................................................................................................22
Product Change Notification Service............................................................................................................22
Customer Support........................................................................................................................................ 22
Microchip Devices Code Protection Feature................................................................................................ 22
Legal Notice................................................................................................................................................. 23
Trademarks.................................................................................................................................................. 23
Quality Management System....................................................................................................................... 24
Worldwide Sales and Service.......................................................................................................................25
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1. Relevant Devices
This section lists the relevant devices for this document. The following figures show the different family devices,
laying out pin count variants and memory sizes:
• Vertical migration upwards is possible without code modification, as these devices are pin-compatible and
provide the same or more features
• Horizontal migration to the left reduces the pin count and, therefore, the available features
• Devices with different Flash memory sizes typically also have different SRAM and EEPROM
Figure 1-1. AVR® DB Family Overview
Pins
Flash
AVR64DB28
AVR128DB28
AVR32DB28
AVR128DB32 AVR128DB48 AVR128DB64
AVR64DB32 AVR64DB48 AVR64DB64
AVR32DB32 AVR32DB48
28 48 64
32
32 KB
64 KB
128 KB
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Relevant Devices
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 4

2. Overview
The MVIO pins, located on PORTC, are powered by a separate VDDIO2 pin while the rest are powered by VDD. This
allows for additional power domain at a different voltage level within the limits of the Electrical Characteristics of each
device.
Figure 2-1. 48-Pin VQFN/TQFP Pinout Diagram
1
2
3
4
44 43
42
41 40
39 38
5
6
7
8
9
10
11
33
32
31
30
29
28
27
26
25
24 23
37
36
35
34
12
13 14
15 16
17 18
19
20 21
22
45
46
47 48
GND VDD
PA5
PA6
PA7
PD2 PD3
PD6
PD7
PB0
PD0 PD1
PA2 PA3
PB1
PB2
PB3
PE1
PE2
PE0
PE3
PF0 (XTAL32K1)
PF1 (XTAL32K2)
PA1 (XTALHF2)
PA0 (XTALHF1)
PD5
PA4
PF2
PC0
PC1
PC4 PC5
PC3
PC2
PC6 PC7
PF3
PF4
UPDI
PF5
PF6
VDDIO2
PB4
PB5
GND
GND
AVDD
PD4
Power
Power Supply
Ground
Pin on AVDD Power Domain
Functionality
Programming/Debug
Clock/Crystal
Analog Function
Digital Function OnlyPin on VDD Power Domain
Pin on VDDIO2 Power Domain
These pins are capable of the same digital behavior as regular I/O pins, for example GPIO, serial communication
(USART, SPI, I2C), or connected to PWM peripherals. The input Schmitt Trigger levels are scaled according to the
VDDIO2 voltage, as described in the Electrical Characteristics section of the data sheet.
A configuration fuse determines the MVIO supply mode. The loss or gain of power on VDDIO2 is signaled by a status
register bit. This status bit has corresponding interrupt and event functionality.
A divided-down VDDIO2 voltage is available as input to the ADC.
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Overview
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 5

Figure 2-2. MVIO Block Diagram
VDDIO
VDDIO2
VDD
PORTx[7:0]
PORTy[7:0]
VDDIO2
PORT
VDDIO2S VDDIO2F
Enable
(Int Req.)
ADC Input
Edge Detector
Voltage Divider
Voltage
Monitor
Voltage
Monitor
VDDCORE
VDDCORE
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Overview
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3. Hardware Configuration
3.1 Using the Curiosity Nano AVR128DB48
To illustrate the capabilities of Multi-Voltage I/O an AVR128DB48 Curiosity Nano is used. Schematics of the Curiosity
Nano PCB can be found in the References section. To enable MVIO on this development board, perform the below
steps:
1. Remove the resistor right below the VDDIO2 label to disconnect VDDIO2 from VDD. This is resistor R204 in
Figure 3-2.
2. Connect VDDIO2 + to 3.3V of a second power voltage source.
3. Connect VDDIO2 - to GND of a second voltage source.
Refer to the AVR123DB48 Curiosity Nano User Guide for a guide on how to reverse this process.
Any voltage between 1.8V and 5.5V may be applied to VDDIO2, but for the following examples, we will run at 3.3V.
Figure 3-1. AVR128DB48 Curiosity Nano MVIO
123
Figure 3-2. Snippet From the AVR128DB48 Curiosity Nano Schematic
3.2 Supplying Power To VDDIO2
The Multi-Voltage I/O (MVIO) can be configured in one of two supply modes:
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Hardware Configuration
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 7

• Single-Supply mode, where the MVIO-capable I/O pins are powered at the same voltage level as the non-MVIO
capable pins, i.e., VDD. The user must connect the VDDIO2 pin(s) to the VDD pin(s).
• Dual-Supply mode, where the MVIO-capable I/O pins are supplied by the VDDIO2 voltage, which may be
different from the voltage supplied to the VDD pin(s)
Figure 3-3. FUSE.SYSCFG1 - Enabling Dual Supply Mode
8.8.2.5 System Configuration 1
Name: SYSCFG1
Offset: 0x06
Default: 0x08
Property: -
The default value given in this fuse description is the factory-programmed value, and should not be mistaken for the
Reset value.
Bit 7 6 5 4 3 2 1 0
SUT[2:0]
Access R R R R R
Default 0 1 0 0 0
Bits 4:3 – MVSYSCFG[1:0]
This bit field controls the power supply mode.
Value Name Description
0x00 Reserved -
0x02 SINGLE Device used in a single supply configuration.
0x03 Reserved -
MVSYSCFG[1:0]
Device used in a dual supply configuration.DUAL
0x01
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Hardware Configuration
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4. Reading the Status Bit
Before using the MVIO feature, it is recommended to check the VDDIO2 Status (VDDIO2S) bit in the MVIO.STATUS
(Status) register, to make sure that the voltage level of VDDIO2 is within the acceptable range of operation. If this bit
is ‘1’, then VDDIO2 is within the acceptable range of operation.
Figure 4-1. MVIO.STATUS - Reading the Status bit
Bit 7 6 5 4 3 2 1 0
Access R
Reset 0
Bit 0 – VDDIO2S VDDIO2 Status
This bit shows the state of the VDDIO2 voltage level.
Writing to this bit has no effect.
Value Description
0The VDDIO2 supply voltage is below the acceptable range for operation. The MVIO pins are tri-stated.
VDDIO2S
The VDDIO2 supply voltage is within the acceptable range for operation. The MVIO pin configurations
are loaded from the corresponding PORT registers.
1
//Polling the VDDIO2S bit
if(MVIO.STATUS & MVIO_VDDIO2S_bm)
{
//Do something if VDDIO2 is within acceptable range.
}
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Reading the Status Bit
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 9

5. Interrupt on VDDIO2 Status
When the state of the VDDIO2 Status bit changes, the VDDIO2 interrupt flag will be raised. To be able to catch this
interrupt immediately, it is necessary to enable both the VDDIO2 interrupt and global interrupts in general.
Figure 5-1. MVIO.INTCTRL - Enable the VDDIO2 Interrupt
Bit 7 6 5 4 3 2 1 0
Access R/W
Reset 0
Bit 0 – VDDIO2IE VDDIO2 Interrupt Enable
This bit controls whether the interrupt for a VDDIO2 state change is enabled or not.
Value Description
0The VDDIO2 interrupt is disabled
VDDIO2IE
The VDDIO2 interrupt is enabled
1
/*Enable the VDDIO2 interrupt*/
MVIO.INTCTRL |= MVIO_VDDIO2IE_bm;
/*Enable Global interrupts*/
sei();
The MVIO vector will be called when the interrupt is triggered. Before returning from the Interrupt Service Routine
(ISR), the VDDIO2 (VDDIO2IF) interrupt flag in the MVIO Interrupt Flags (MVIO.INTFLAGS) register must be cleared.
This is done by writing a ‘1’ to the flag.
Figure 5-2. MVIO.INTFLAGS - Clear VDDIO2 Interrupt Flag
Bit 7 6 5 4 3 2 1 0
Access R/W
Reset 0
Bit 0 – VDDIO2IF VDDIO2 Interrupt Flag
This flag is cleared by writing a ‘1’ to it.
This flag is set when the VDDIO2 Status (VDDIO2S) bit in MVIO.STATUS changes value.
Writing a ‘0’ to this bit has no effect.
Writing a ‘1’ to this bit will clear the VDDIO2 Interrupt Flag.
VDDIO2IF
ISR(MVIO_MVIO_vect)
{
/* The VDDIO2 interrupt has been triggered */
LED0_toggle();
/* Clear the CFD interrupt flag */
MVIO.INTFLAGS |= MVIO_VDDIO2IF_bm;
}
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Interrupt on VDDIO2 Status
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 10

6. Measuring VDDIO2
The internal ADC has VDDIO2 divided by 10 as an input, making it possible to measure the voltage of the VDDIO2
domain even with the internal 1.024V reference.
First, we select the 1.024V reference for ADC0 in the ADC0REF register, as shown below. Note that this register is
located in the Voltage Reference Section(VREF), not the ADC section.
Figure 6-1. VREF.ADC0REF - Select 1V024 as Reference for ADC0
Bit 7 6 5 4 3 2 1 0
ALWAYSON
Access R/W R/W R/W R/W
Reset 0 0 0 0
Bits 2:0 – REFSEL[2:0] Reference Select
This bit field controls the reference voltage level for ADC0.
Note:
1. The values given for internal references are only typical. Refer to the Electrical Characteristics section for
further details.
Value Name Description
0x1 2V048 Internal 2.048V reference(1)
0x2 4V096 Internal 4.096V reference(1)
0x3 2V500 Internal 2.500V reference(1)
0x4 - Reserved
0x5 VDD VDD as reference
0x6 VREFA External reference from the VREFA pin
0x7 - Reserved
REFSEL[2:0]
0x0 1V024 Internal 1.024V reference(1)
/*Select the 1.024V referance for ADC0*/
VREF.ADC0REF = VREF_REFSEL_1V024_gc;
Select the VDDIO2DIV10 as input for ADC0 on the positive input pin.
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Measuring VDDIO2
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Figure 6-2. ADC0.MUXPOS - Select VDDIO2DIV10 as Input for ADC0
Bit 7 6 5 4 3 2 1 0
Access R/W R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0 0
Bits 6:0 – MUXPOS[6:0] MUX Selection for Positive ADC Input
This bit field selects which analog input is connected to the positive input of the ADC. If this bit field is changed during
a conversion, the change will not take effect until the conversion is complete.
Value Name Description
0x00-0x0F AIN0-AIN15 ADC input pin 0-15
0x10-0x15 AIN16-AIN21 ADC input pin 16-21
0x16-0x1F - Reserved
0x20-0x3F - Reserved
0x40 GND Ground
0x41 - Reserved
0x42 TEMPSENSE Temperature sensor
0x44 VDDDIV10 VDD divided by 10
0x48 DAC0 DAC0
Other - Reserved
MUXPOS[6:0]
0x45 VDDIO2DIV10 VDDIO2 divided by 10
/*Select VDDIO2DIV10 as input for ADC0*/
ADC0.MUXPOS = ADC_MUXPOS_VDDIO2DIV10_gc;
The ADC has built-in support for oversampling. This is especially useful when measuring a DC voltage, as it mitigates
a lot of the periodic noise.
Figure 6-3. ADC0.CTRLB - Enabling Oversampling with 16 Samples
Bit 7 6 5 4 3 2 1 0
Access R/W R/W R/W
Reset 0 0 0
Bits 2:0 – SAMPNUM[2:0] Sample Accumulation Number Select
This bit field selects how many consecutive ADC sampling results are accumulated automatically. When this bit field
is written to a value greater than 0x0, the according number of consecutive ADC sampling results are accumulated
into the ADC Result (ADCn.RES) register.
Value Name Description
0x0 NONE No accumulation
0x1 ACC2 2 results accumulated
0x2 ACC4 4 results accumulated
0x3 ACC8 8 results accumulated
0x4 ACC16 16 results accumulated
0x6 ACC64 64 results accumulated
0x7 ACC128 128 results accumulated
SAMPNUM[2:0]
0x5 ACC32 32 results accumulated
/* Enable 16 oversamples*/
ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc;
Enable ADC0.
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Measuring VDDIO2
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 12

Figure 6-4. ADC0.CTRLA - Enable ADC0
Bit 7 6 5 4 3 2 1 0
RUNSTDBY CONVMODE LEFTADJ RESSEL[1:0] FREERUN
Access R/W R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0 0
Bit 0 – ENABLE ADC Enable
Value Description
0ADC is disabled
ENABLE
1ADC is enabled
/*Enable ADC0*/
ADC0.CTRLA = ADC_ENABLE_bm;
It is now possible to start measurement by writing a ‘1’ to the STCON (Start Conversion) bit in the Command
(ADC0.COMMAND) register.
Figure 6-5. ADC0.COMMAND - Start a Measurement
Bit 7 6 5 4 3 2 1 0
SPCONV
Access R/W R/W
Reset 0 0
Bit 0 – STCONV Start Conversion
Writing a ‘1’ to this bit will start a conversion as soon as any ongoing conversions are completed. If in Free-Running
mode, this will start the first conversion. STCONV will read as ‘1’ as long as a conversion is in progress. When the
conversion is complete, this bit is automatically cleared. Writing a ‘0’ to this bit has no effect.
STCONV
/*Start an ADC conversion*/
ADC0.COMMAND = ADC_STCONV_bm;
After a conversion is started, it is necessary to wait for it to be done before reading the result. The RESRDY (Result
Ready) interrupt flag in the Interrupt Flags (ADC0.INTFLAGS) register will be triggered when a result is ready in the
Result (ADC0.RES) register.
Figure 6-6. ADC0.INTFLAGS - Check RESRDY Interrupt Flag
Bit 7 6 5 4 3 2 1 0
WCMP
Access R/W R/W
Reset 0 0
Bit 1 – WCMP Window Comparator Interrupt Flag
This window comparator flag is set when the measurement is complete and if the result matches the selected
Window Comparator mode defined by the WINCM bit field in the Control E (ADCn.CTRLE) register. The comparison
is done at the end of the conversion. The flag is cleared by either writing a ‘1’ to the bit position or by reading the
Result (ADCn.RES) register. Writing a ‘0’ to this bit has no effect.
Bit 0 – RESRDY Result Ready Interrupt Flag
The Result Ready interrupt flag is set when a measurement is complete and a new result is ready. The flag is cleared
by either writing a ‘1’ to the bit location or by reading the Result (ADCn.RES) register. Writing a ‘0’ to this bit has no
effect.
RESRDY
/*Wait for the ADC conversion to be done*/
while(!(ADC0.INTFLAGS & ADC_RESRDY_bm));
The result can be read in the Result (ADC0.RES) register. The result must be divided by 16 due to the oversampling.
This is easily done by right shifting the value in ADC0.RES 4 bits. The RESRDY interrupt flag will be automatically
cleared when ADC0.RES is read.
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Measuring VDDIO2
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 13

Figure 6-7. ADC0.RES - Read the Result
Bit 15 14 13 12 11 10 9 8
Access R R R R R R R R
Reset 0 0 0 0 0 0 0 0
Bit 7 6 5 4 3 2 1 0
Access R R R R R R R R
Reset 0 0 0 0 0 0 0 0
Bits 15:8 – RES[15:8] Result High Byte
This bit field constitutes the high byte of the ADCn.RES register, where the MSb is RES[15].
Bits 7:0 – RES[7:0] Result Low Byte
This bit field constitutes the low byte of the ADCn.RES register.
RES[15:8]
RES[7:0]
/*Read the RES register and shift the result 4 bits to compensate for the 16 oversamples*/
uint16_t result = (ADC0.RES>>4);
TB3287
Measuring VDDIO2
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 14

7. Blinking a 3V LED with VDD at 1.8V
Following the instructions in the Hardware Configuration section to supply VDDIO2 with 3.3V and VDD with 1.8V.
Make sure that VDDIO2 and VDD have the correct voltage levels by using a multi-meter.
Following the instruction in the 4. Reading the Status Bit section, we check that VDDIO2 is within acceptable range
before starting the blinking.
Make sure the LED has a forward voltage of approximately 3V by using a multimeter with diode testing capabilities. A
green LED usually has a forward voltage of approximately 3V.
An external green LED in series with a resistor of at least 15 Ohms needs to be connected to PC0, like shown in the
figure below.
If a different LED is used, the resistor value needs to change. This is calculated using the following formula where
VLED is the voltage drop of the LED and ALED is current through the LED:
=
2 

WARNING
The AVR DB can not be programmed below 2V, so to ensure proper operation, set VDD to 3.3V by
dragging and dropping the provided text file “VDD3V3.txt” onto the “CURIOSITY” drive on your PC. When
programming is done, lower VDD to 1.8V by dragging and dropping “VDD1V8.txt” to the “CURIOSITY”
drive. Both .txt files can be found in the GitHub repository linked in the introduction.
Figure 7-1. Curiosity Nano AVR128DB48 - LED Circuit Physical Layout
R1 D1
External
voltage
Supply
3.3V
On-board
voltage
regulator
Resistor remains
removed as described
in HW Configuration
TB3287
Blinking a 3V LED with VDD at 1.8V
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 15

Figure 7-2. LED Circuit Schematics
VDDIO2
I/O Powered by VDDIO2
GND
MVIO
VDD
On-board
voltage
regulator
External
voltage
Supply
1.8V
3.3V
R1
D1
VDD
VDDIO2
PC0
MVIO
D1
/*Blinking a 3V LED with VDD at 1.8V*/
/*Set LED pin to output*/
void LED_PC0_init(void)
{
PORTC.DIRSET = PIN0_bm;
}
/*Toggle LED pin*/
void LED_PC0_toggle(void)
{
PORTC.OUTTGL=PIN0_bm;
}
int main(void)
{
LED_PC0_init();
while (1)
{
/*Check if VDDIO2 is within acceptable range*/
if(MVIO.STATUS & MVIO_VDDIO2S_bm)
{
/*Blink LED at PC0 forever*/
while (1)
{
LED_PC0_toggle();
_delay_ms(250);
}
}
}
}
The code for this example is available in the blinking-a-3v0-led-with-vdd-at-1v8 folder in these github repositories
TB3287
Blinking a 3V LED with VDD at 1.8V
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 16

8. References
1. AVR128DB48 product page: www.microchip.com/wwwproducts/en/AVR128DB48.
2. AVR128DB48: www.microchip.com/DS40002247.
3. Curiosity Nano AVR128DB48 product page: www.microchip.com/DevelopmentTools/ProductDetails/PartNO/
EV35L43A.
4. AVR128DB48 Curiosity Nano User Guide: www.microchip.com/DS50003037.
5. Curiosity Nano AVR128DB48 Schematics ww1.microchip.com/downloads/en/DeviceDoc/
AVR128DB48_Curiosity_Nano_Schematics.pdf.
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References
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 17

9. Revision History
Doc. Rev. Date Comments
A 09/2020 Initial document release.
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Revision History
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 18

10. Appendix
Code examples for each use case in this technical brief.
Example 10-1. Polling VDDIO2 Status
#define F_CPU 4000000ul
#include <avr/io.h>
int main(void)
{
while (1)
{
/*Check if VDDIO2 is within acceptable range*/
if(MVIO.STATUS & MVIO_VDDIO2S_bm)
{
/* Replace with your application code */
}
}
}
Example 10-2. Interrupt on VDDIO2 Status
#define F_CPU 4000000ul
#include <avr/io.h>
#include <avr/interrupt.h>
void LED0_init(void) {
PORTF.DIRSET = PIN5_bm;
}
void LED0_toggle(void) {
PORTF.OUTTGL = PIN5_bm;
}
int main(void)
{
/*Enable the VDDIO2 interrupt*/
MVIO.INTCTRL |= MVIO_VDDIO2IE_bm;
/*Enable Global interrupts*/
sei();
LED0_init();
/* Replace with your application code */
while (1)
{
}
}
ISR(MVIO_MVIO_vect)
{
/* The VDDIO2 interrupt has been triggered */
LED0_toggle();
/* Clear the CFD interrupt flag */
MVIO.INTFLAGS |= MVIO_VDDIO2IF_bm;
}
Example 10-3. Measuring VDDIO2
#define F_CPU 4000000ul
/*Initialize ADC0*/
void adc0_init(void)
{
/*Select the 1.024V referance for ADC0*/
VREF.ADC0REF = VREF_REFSEL_1V024_gc;
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Appendix
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 19

/* Enable 16 over samples*/
ADC0.CTRLB = ADC_SAMPNUM_ACC16_gc;
/*Enable ADC0*/
ADC0.CTRLA = ADC_ENABLE_bm;
}
/*Measure VDDIO2 using the internal ADC*/
uint16_t read_VDDIO2()
{
/*Select VDDIO2DIV10 as input for ADC0*/
ADC0.MUXPOS = ADC_MUXPOS_VDDIO2DIV10_gc;
/*Start an ADC conversion*/
ADC0.COMMAND = ADC_STCONV_bm;
/*Wait for the ADC conversion to be done*/
while(!(ADC0.INTFLAGS & ADC_RESRDY_bm));
/*Read the RES register and shift the result 4 bits to compensate for the
16 oversamples*/
uint16_t result = (ADC0.RES>>4);
return result;
}
int main(void)
{
adc0_init();
/* Replace with your application code */
while (1)
{
/*Read the VDDIO2 voltage continiously*/
read_VDDIO2();
}
}
Example 10-4. Blink a 3V LED with VDD at 1.8V
#define F_CPU 4000000ul
#include <avr/io.h>
#include <util/delay.h>
void LED_PC0_init(void)
{
PORTC.DIRSET = PIN0_bm;
}
void LED_PC0_toggle(void)
{
PORTC.OUTTGL=PIN0_bm;
}
int main(void)
{
LED_PC0_init();
while (1)
{
/*Check if VDDIO2 is within acceptable range*/
if(MVIO.STATUS & MVIO_VDDIO2S_bm)
{
/*Blink LED at PC0 forever*/
while (1)
{
LED_PC0_toggle();
_delay_ms(250);
}
}
TB3287
Appendix
© 2020 Microchip Technology Inc. Technical Brief DS90003287A-page 20