accel_data_influx.py

# MMA8452Q setup and query code from ControlEverything
# https://github.com/ControlEverythingCommunity

import os
import smbus
import time
import signal
import sys
from datetime import datetime
from influxdb import InfluxDBClient

def signal_handler(signal, frame):
        print 'You pressed Ctrl+C!'
        sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
print 'Press Ctrl+C to exit'

#fname = 'accel_data_out'
#try:
#    os.unlink(fname)
#except:
#    print "no previous data file to remove"

# Get I2C bus
bus = smbus.SMBus(1)

# MMA8452Q address, 0x1D(28)
# Select Control register, 0x2A(42)
#		0x00(00)	StandBy mode
bus.write_byte_data(0x1D, 0x2A, 0x00)
# MMA8452Q address, 0x1D(28)
# Select Control register, 0x2A(42)
#		0x01(01)	Active mode
bus.write_byte_data(0x1D, 0x2A, 0x01)
# MMA8452Q address, 0x1D(28)
# Select Configuration register, 0x0E(14)
#		0x00(00)	Set range to +/- 2g
bus.write_byte_data(0x1D, 0x0E, 0x00)

time.sleep(0.5)

i = 0

#fout = open(fname, 'w')
#fout.write( "time, X, Y, Z\n" )

# while i < 432000: # 6 hour runtime
while True: # continuous run

    # MMA8452Q address, 0x1D(28)
    # Read data back from 0x00(0), 7 bytes
    # Status register, X-Axis MSB, X-Axis LSB, Y-Axis MSB, Y-Axis LSB, Z-Axis MSB, Z-Axis LSB
    data = bus.read_i2c_block_data(0x1D, 0x00, 7)

    # Convert the data
    xAccl = (data[1] * 256 + data[2]) / 16
    if xAccl > 2047 :
        xAccl -= 4096

    yAccl = (data[3] * 256 + data[4]) / 16
    if yAccl > 2047 :
        yAccl -= 4096

    zAccl = ((data[5] * 256 + data[6]) / 16) - 1000
    if zAccl > 2047 :
        zAccl -= 4096

    # Output data to DB
    ts = int(round(time.time() * 1000))
    fmtts = datetime.utcnow().strftime('%Y-%m-%dT%H:%M:%S.%f')[:-3]
    #print ts
    # print a timestamp to show activity
    if i%200 == 0:
        print fmtts
    #print "Acceleration in X-Axis : %d" %xAccl
    #print "Acceleration in Y-Axis : %d" %yAccl
    #print "Acceleration in Z-Axis : %d" %zAccl
    json_body = []
    xval = {
            "measurement": "accels",
            "time_precision": "ms",
            "time": fmtts,
            "tags": {
            "dim": "X",
            },
            "fields": {
                "value": xAccl
            }
        }
    json_body.append(xval)
    yval = {
            "measurement": "accels",
            "time_precision": "ms",
            "time": fmtts,
            "tags": {
            "dim": "Y",
            },
            "fields": {
                "value": yAccl
            }
        }
    json_body.append(yval)
    zval = {
            "measurement": "accels",
            "time_precision": "ms",
            "time": fmtts,
            "tags": {
            "dim": "Z",
            },
            "fields": {
                "value": zAccl
            }
        }
    json_body.append(zval)
    #print json_body
    client = InfluxDBClient(host='localhost', port=8086, database='accel_data')
    client.write_points(json_body)
    #fout.write( str(ts) + ", " + str(xAccl) + ", " + str(yAccl) + ", " + str(zAccl) + "\n" )
    #time.sleep(0.0086)
    i = i + 1

#fout.close()