I2C programming in Accelerometer

[Zain Dar]

Hi, I'm working on two accelerometers, both of them are digital (ADXL345 by sparkfun) and I'm having trouble programming them to display the X, Y and Z axis. I'm trying the code in python first because its alot easier to work with and much faster to learn than C++ but I haven't had much luck in finding tutorials that make sense. Derek Molloys tutorial of the same topic is good but it comes with some problems that I'm unable to solve. He requires to install a number of other packages that are temporarily unavailable online for downloading into my BBB so I have to result to alternate ideas and code examples. Can someone please kindly direct me to a sample code that I can try out?

Thanks 

[Pedro A. Melendez]

you can use for i2c with python the adafruit library fro the beaglebone or if you like to use nodejs there is node-i2c. I used node-i2c to make a custom driver for the ds1337 rtc and it worked pretty nice.

-Pedro

On Sun, Nov 17, 2013 at 12:25 AM, Zain Dar <zain...@gmail.com> wrote:

Hi, I'm working on two accelerometers, both of them are digital (ADXL345 by sparkfun) and I'm having trouble programming them to display the X, Y and Z axis. I'm trying the code in python first because its alot easier to work with and much faster to learn than C++ but I haven't had much luck in finding tutorials that make sense. Derek Molloys tutorial of the same topic is good but it comes with some problems that I'm unable to solve. He requires to install a number of other packages that are temporarily unavailable online for downloading into my BBB so I have to result to alternate ideas and code examples. Can someone please kindly direct me to a sample code that I can try out?

Thanks 

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[Pedro A. Melendez]

http://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black/i2c
https://github.com/kelly/node-i2c

[Zain Dar]

Thanks for the advice and the links! So, I noticed that the ADXL345 is made in the node-i2c github as a project. There are a number of files in it, so the one that has the code for the working of the accelerometer is the one that is labeled "index.js"? also since I haven't made a code in the .js format, is this done from the terminal or from the cloud9ide? thanks again!

http://learn.adafruit.com/setting-up-io-python-library-on-beaglebone-black/i2c
https://github.com/kelly/node-i2c

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[Pedro A. Melendez]

Same as python, just write 'node scriptname.js'. I'm not sure if you can use run it from cloud9

-Pedro

[Zain Dar]

I made the code for the z axis of the accelerometer but i just need some help on how to adjust it for the X and Y axis. Heres the sample code for the z axis. 

import smbus
import time
def main():

  bus = smbus.SMBus(1)
 
	# Power-on the accelerometer, enabling only the z-axis
	bus.write_byte_data(0x18, 0x20, 0x24)
 
	try:

		while True:
      # get z-axis acceleration
			tilt = bus.read_byte_data(0x18, 0x2D)
 
      # if it's supposed to be negative
			if tilt > 127:
        # then convert it to the absolute value of the negative value

				tilt = 256 + ~tilt
				positive = False
			else:
				positive = True
 
      # format and print it

			pos = tilt / 2
			print str(tilt).rjust(6),
			if positive:

				print 65*' ' + '|' + (pos*'#').ljust(65)
			else:
				print (pos*'#').rjust(65) + '|' + 65*' '
			
      # sleep

      time.sleep(0.1)
      
	except KeyboardInterrupt:
		# restore default settings
		bus.write_byte_data(0x18, 0x20, 0x07)
 
if __name__ == '__main__':
	main()


I only need an idea for the X and Y axis. Thanks to anyone who can help.

[rod0...@gmail.com]

Im here with the same problem did you ever find a solution?