RPI Current sensor

#!/usr/bin/python

import spidev
import time
import os

# Schematic values
resVal = 23
ratio = 2000
zeroVal = 1.66

# Open SPI bus
spi = spidev.SpiDev()
spi.open(0,0)

# Function to read SPI data from MCP3008 chip
# Channel must be an integer 0-7
def ReadChannel(channel):
  adc = spi.xfer2([1,(8+channel)<<4,0])
  data = ((adc[1]&3) << 8) + adc[2]
  return data

# Function to convert data to voltage level,
# rounded to specified number of decimal places.
def ConvertVolts(data,places):
  volts = (data * 3.3) / float(1023)
  volts = round(volts,places)
  return volts

# Define sensor channels
sensor_channel = 0

# Define delay between readings
delay = 1

# Define voltage drop
volDif = 0

while True:

  # Read the current sensor data
  sensor_level = ReadChannel(sensor_channel)
  sensor_volts = ConvertVolts(sensor_level,2)

  # Define
  if sensor_volts>1.66:
   volDif = sensor_volts - 1.66
  else:
   volDif = 1.66 - sensor_volts

  # Calc Amps secondary
  sensorAmpsec = (volDif / resVal) * 1000

  # Calc Amps primary
  sensorAmpsprim = (sensorAmpsec / 1000) * ratio

  # Print out results
  print "--------------------------------------------"
  print("Bits: {} ({}V)".format(sensor_level,sensor_volts))
  print("Amps: SEC - {} mA | PRIM - {} A".format(round(sensorAmpsec,2),round(sensorAmpsprim,2)))

  # Wait before repeating loop
  time.sleep(delay)