Saturday 23 May 2015

arduino - SPI and pull-up resistors


I have a breakout that comes with two 10kOhm resistors: one on the SDA and one on SCL. The chip takes a max of 3.6V. AFAIK, I2C needs pull-ups on its pins, but could SPI be used on this module? I'm powering it with an Arduino and SCL seems to be around 4.5V - is it too high or is the pull-up going to shift it down?


Thanks



EDIT


The schematic of the breakout is essentially this:


enter image description here



Answer



If you want to use the SPI bus, you need to remove the pull-up resistors.


You need to connect all wire lines like SDI, SDO, SPC and CS to the master device.


The LIS3DH is not 5V tolerant and the maximum voltage is 3.6V. If you put higher voltage, you will damage the chip inputs.


You can put logic level translator between the Arduino card and your LIS3DH card.


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