Python wrapper for Atlas Scientific USB sensors

Installing dependencies.

Install libftdi package.
```
  sudo apt-get install libftdi-dev 
```
Install pylibftdi python package.
```
  sudo pip install pylibftdi
```

Install dependencies

  sudo apt-get install sqlite
  sudo pip install xlwt

Create SYMLINK of the FTDI adaptors.

The following will allow ordinary users (e.g. ‘pi’ on the RPi) to access to the FTDI device without needing root permissions:

If you are using device with root permission, just skip this step.

Create udev rule file by typing sudo nano /etc/udev/rules.d/99-libftdi.rules and insert below:
```
  SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6015", GROUP="dialout", MODE="0660", SYMLINK+="FTDISerial_Converter_$attr{serial}"
```
Press CTRL+X, Y and hit Enter to save & exit.

Restart udev service to apply changes above.
```
  sudo service udev restart
```

Modify FTDI python driver

Since our FTDI devices use other USB PID(0x6015), we need to tweak the original FTDI Driver.

  sudo nano /usr/local/lib/python2.7/dist-packages/pylibftdi/driver.py

Move down to the line 70 and add 0x6015 at the end of line.

Original line:

  USB_PID_LIST = [0x6001, 0x6010, 0x6011, 0x6014]

Added line:

  USB_PID_LIST = [0x6001, 0x6010, 0x6011, 0x6014, 0x6015]

Testing Installation.

Connect your device, and run the following (as a regular user):
```
  python -m pylibftdi.examples.list_devices
```
If all goes well, the program should report information about each connected device.

If no information is printed, but it is when run with sudo,

a possibility is permissions problems - see the section under Linux above regarding udev rules.

You may get result like this:
```
  FTDI:FT230X Basic UART:DA00TN73
```
FTDI adaptors has its own unique serial number.

We need this to work with our sensors.

In the result above, serial number is DA00TN73.

Install library

cd ~
git clone https://github.com/Atlas-Scientific/R-pi-database-.git
cd R-pi-database-
sudo python setup.py install

Test library

Here is the basic sample code.

import pylibAtlas      # import pylibAtlas library

db_test = 'test1.sqlite'
table_test = 'tb_test'

# Create database file and also table with given parameter.
# Note that the table has columns named id, time stamp, val1, val2, val3, val4 to store sensor data. 
pylibAtlas.create_table(db_test, table_test)    

# Once creating the database file and table, now let us read data from the sensor and save to db.
# Assume that sensor data has been saved to sensor_val variable.
pylibAtlas.insert_data(db_test, table_test, sensor_val)

# Now let us try to get last commited value
print "Last value:", pylibAtlas.get_last_value(db_test, table_test)

# Maximum value through the whole db
print "Max value: ", pylibAtlas.get_max_value(db_test, table_test)

# Minimum value through the whole db
print "Min value: ", pylibAtlas.get_min_value(db_test, table_test)

# When we forget table name, we can use this function to get table name from the db file.
print "Table name: ", pylibAtlas.get_table_name(db_test)

# export to excel file which has same file name with db file.
# test1.xlsx file will be created in the same directory.
print "Exporting: ", pylibAtlas.export_xls('test1.sqlite')