Arduino Forum

Products => Arduino Due => Topic started by: bglsmith on Feb 19, 2013, 02:13 am

Title: 5V on SPI
Post by: bglsmith on Feb 19, 2013, 02:13 am
I just bought a Due board and am really impressed.  I'm very new to electronics and I'm still trying to understand all of the 3.3V and 5V differences and ramifications.

// Pinout diagram
http://arduino.cc/forum/index.php?topic=132130.0

I'm a little confused about the SPI header.  If the MOSI, MISO, and SCK pins can only handle 3.3V why does the SPI supply 5V?
Title: Re: 5V on SPI
Post by: shteii01 on Feb 19, 2013, 02:37 am
It might be just for power.  I have been having discussion about real time clock unit, it is powered by 5 volts, but for communication it can use other voltages (Logic 0: -0.3 to 0.8 volts; Logic 1: 2.2 to Vcc+0.3 volts).  As you can see the communication voltages are not tied up to the voltage needed to power the device.
Title: Re: 5V on SPI
Post by: bglsmith on Feb 24, 2013, 06:20 am
What you've explained makes a lot of sense.  I used the SPI header to connect to a breakout board and it works just fine.  Thanks!