Hi all,
I want to use a MAX6682 Thermistor to Digital chip with an Arduino Uno. As the MAX6682 uses a 3V3 Vcc, I plan to power the chip from Uno's 3V3 output.
The MAX6682 uses a SPI interface to communicate.
Seeing as the MAX6682 has a 3V3 Vcc, does this mean I would need level shifting between the chip and the Uno for the SPI pins?
If so, would it be for all 3 SPI pins?
Thanks in advance 
see datasheet http://datasheets.maximintegrated.com/en/ds/MAX6682.pdf
..indicates 5v tolerant.
For safety run 3.3V and a 5-10k resistor in series with clk an Dout (mosi)
You probably only need to drop the voltage for the signals that go from Uno to the 3.3v device - MOSI and CLOCK. The Uno should be able to "receive" the 3.3v signals without any problem.
I have successfully dropped the voltage to a 3v device with this simple circuit (one for each pin)
Arduino Pin --------- LED -------- resistor ------- ground
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input pin on 3v device
The LED causes a voltage drop of about 3v and has the added advantage that it flashes when things are working.
...R