I want to use some 3.3V sensors and the ILI9341 display without levelshifter.
After loading the program to Arduino NANO R4 over USB I discaonnect USB,
the I put DC - Pin direct to pin 9, CS to 10, MOSI to 11 and SCL to 13 and the RST Pin to the 3.3V Pin of the Arduino NANO R4.
I power then the Nano with an extern 3.3V source on Pin 5V of the NANO R4.
The result You can see on the small Video:
Do the ADC, DAC and op-amp still meet specifications?
Can the Digital I/O still supply 8mA?
Does the battery backup still work?
Does the I2C on the QWIIC connector still work.
What is the current consumption at 3.3V?
I have only tested the NANO R with the 2.8 “ SPI display, no other functions.
The consumption include the display is about 60 mA.
The display works with the NANO R down to 2.6 V.
The processor is probably working down to 2.5 V, but the display is then nearly dark.
I think QWIK is and the opamp not working , perhaps ADC and DAC , but if then slower.
You have to test it.
I'll just do it the right way and use level shifters.
Now I have made a low impedance divider (2k/1k) and the display works up to SPI-speed 24 MHz.
The other used SPI-device (MCP4822 DAC) need no divider and work with 20 MHz.
I have no information of the sampling rate of the intern. ADC’s of the ARDUINO R4 for example with 12 bit resolution.