16+ Arduino Mega Pinout I2C Pictures. 20 y 21 or near the usb purto? When cheaper boards are available, why go with arduino mega?

Bh1750 Sensor Interfacing With Arduino Measure Ambient Light
Bh1750 Sensor Interfacing With Arduino Measure Ambient Light from microcontrollerslab.com
It has 54 digital input/output pins (of which 14 can be used as pwm outputs), 16 analog. Usb (programming with atmega 8), icsp (programming), spi, i2c and usart. Support i2c aka iic aka twi communication using the wire library.

Power supply i2c is a communication protocol commonly referred to as the i2c bus.

I recently upgraded my shapeoko from an arduino uno to a mega and i am using a cnc stepper shield designed for the uno. All analog pins can be used as two pins 20 and 21 support i2c communication where 20 represents sda (serial data line mainly used for holding the data) and 21 represents scl. (for example, google arduino mega pinout, and check the images). Note that these pins are not in the same location as the twi/i2c pins on the duemilanove or diecimila.