SDCard directly to Arduino 3V3

Other Hardware General Electronics
1

Hi

I have a question.
If a use a power supply 3V3 for my arduino/ATMega328, the SPI pins will works in 3V3 AND I could connect directly a SDcard to this pins without use a logic level shifter IC ?

Thanks very much

2

Yes, if your Arduino would run at 16MHz at that voltage.

It probably will but it is below the voltage that the chip is guaranteed to work at, for this frequency.

3

Why 16MHZ why not 8MHZ ?

4

Yes, but as Mike says, there may be other complications, and you may end up having to burn new fuse values and a new bootloader, particularly if you change the clock rate.

I've found that the little breakout boards for microSD cards cost about the same with or without the level shifter I/C. And the ones with the I/C also have a 3.3V regulator so the entire board can be powered with 5V.

So I would say if you are going to switch the Arduino to 3.3V only to match the bare SD card, it's not clear you would gain much doing that.

5

ShermanP:
Yes, but as Mike says, there may be other complications, and you may end up having to burn new fuse values and a new bootloader, particularly if you change the clock rate.

I've found that the little breakout boards for microSD cards cost about the same with or without the level shifter I/C. And the ones with the I/C also have a 3.3V regulator so the entire board can be powered with 5V.

So I would say if you are going to switch the Arduino to 3.3V only to match the bare SD card, it's not clear you would gain much doing that.

The reason to try use all in 3V3 volts is : Because I am working in a small project battery powered (3.7 Li-On) where the modules include SIM7600 module, SDCard module, Arduino mini 3V3 and a sensor 5V, but I will use a step up 5V circuit to power the sensor. Then using a voltage divider get a 3V3 voltage range output (original 0.5 to 5v)

Using 3v3 I can delete/remove Linear Regulators, then I think using sleep mode in arduino (without leds) and without linear regulator 5v to 3v3 and using Load switch to connect the modules when I need only, I will save battery

sorry my english :confused:

6

How are you going to get the 3.7V battery supply down to 3.3V?