Good day,

I am currently working with an Arduino (Uno) / Accelerometer (ADXL345) / Thermal couple (ktype)

I am doing a project which requires measuring of vibration and temperature. I am using the I2C connection for the accelerometer and the thermal couple, as I need it to be in time domain. Does it means that I have used up the two I2C communication type? Even if there is somemore empty port left?

I am really confused about the SPI/I2C/PWI, the 6 analog and 14 digital input thingy.
Would appreciate if someone could enlighten me a little.

Thank you!


I2C is a bus. Check out a bus. Lots of seats. Each has a number, so you can address the passenger in any given seat.

All I2C communication is done using just two pins, regardless of how many devices there are on the bus.

"Thingy" is not a technical term.

There is no PWI, but there is TWI. The manufacturer of the chip calls it TWI, but we all call it the I2C bus. Just forget the TWI, it is I2C.
The I2C bus uses only 2 wires (SDA and SCL) and GND of course.

The SPI is also a bus, but more wires are needed.

With an Arduino Uno, the chip has the I2C bus combined with analog input A4 and A5. That is how the chip is made, it can not be changed.

Don't jump ahead and try to make your final project work, but try some examples first. That is the best way to learn about Arduino. Ask on the forum, if you don't understand something. It might be a little overwhelming, but it is not that hard.

Look at this : http://www.pighixxx.com/test/portfolio-items/uno/?portfolioID=314
It shows that every pin has a number of functions.

The SPI is also a bus, but more wires are needed.

Only 2- clock (same for both), data from master to slave (MOSI), data from slave to master (MISO) (vs making a single data line do double duty), and a chip select.
The advantage? The clock can be 20 times faster ( 8 MHz vs 400 KHz max) and data can flow in both directions at the same time, so the effective data transfer rate is waaaaaay faster.

thanks guys! Really appreciate your valuable inputs!