Introduction

This guide will walk you through Interfacing with Arduino Shields that use I2C bus.

Hardware Setup

Software setup

Running the Demos

  • The I2C ports on the Arduino and Raspberry Pie headers act as a pass-through to the I2C0 Pins on the Low Speed Header.
  • We first need to enable the i2c pass-through: sudo i2cset 0 0x6f 0x13 0x00
  • This means and device connected over I2C via the FPGA Mezzanine should show up by simply running: sudo i2cdetect -r 0

MPU6050: C

For the MPU6050, we are going to use one of the example codes from the MRAA repository:

  • Fetch the code: wget https://raw.githubusercontent.com/intel-iot-devkit/mraa/master/examples/c/i2c_mpu6050.c
  • Compile the code: gcc i2c_mpu6050.c -o i2c_mpu6050 -lmraa
  • Run the code: sudo ./i2c_mpu6050
  • After 5 seconds you should see Accelerometer and Gyroscope data show up and refresh every 2 seconds.

I2C 1602 LCD and PCA9685 Servo Controller: Python

For a combined demo of LCD module and PCA9685 Servo controller here is a small python script using the UPM Library:

  • Carefully snap the Servo Shield on the Arduino headers of the FPGA mezzanine.
  • Connect the I2C LCD to the I2C pins on the Servo Shield
  • Connect a 5v Servo on Channel 0.
  • Copy the following code and save it as servo.py 
from upm import pyupm_adafruitss as adass
from upm import pyupm_lcm1602 as lcm1602
import time

serv = adass.adafruitss(0,0x40)
lcd = lcm1602.Lcm1602()

lcd.displayOn()
lcd.clear()
lcd.setCursor(0,0)
lcd.write("Hello OpenHours")
lcd.setCursor(1,0)

while True:
    serv.servo(0,1,0)
    lcd.write("Servo Pos: 0  ")
    lcd.setCursor(1,0)
    time.sleep(1)
    serv.servo(0,1,90)
    lcd.write("Servo Pos: 90 ")
    lcd.setCursor(1,0)
    time.sleep(1)
    serv.servo(0,1,160)
    lcd.write("Servo Pos: 160")
    lcd.setCursor(1,0)
    time.sleep(1)
  • Run it as python3 servo.py
  • The servo should now start moving and the LCD should display the servo’s current position.

Video Demo

video