atlas_hydro.py

#!/usr/bin/env python

import time
from pylibftdi.device import Device
from pylibftdi.driver import FtdiError
from sets import Set


class AtlasDevice(Device):

	def read_line(self):
		"""
		Read the response from the Atlas Sensor
		:return:
		"""
		line_buffer = []
		try:
			start_time = time.time()
			while True:
				# read bytes until Carriage Return is received.
				next_char = self.read(1)  # read one byte
				if next_char == "\r":  # sensor always ends with CR.
					break
				line_buffer.append(next_char)
				if time.time() - start_time > 1.0:  # timeout
					line_buffer = ''
					break
			return ''.join(line_buffer)

		except FtdiError:
			return ''

	def send_cmd(self, cmd):
		"""
		Send command to the Atlas Sensor.
		Before sending, add Carriage Return at the end of the command.
		:param cmd:
		:return:
		"""

		buf = cmd + "\r"  # add carriage return
		try:
			self.write(buf)
			return True
		except FtdiError:
			print ("Failed to send command to the sensor.")
			return False


def read_sensors():

	readings = []
	ref_temp = 25

	for sensor in sensors:

		if sensor["sensor_type"] == "atlas_scientific_temp":
			# instantiate atlas scientific temp device
			dev = AtlasDevice(sensor["serial_number"])
			dev.send_cmd("R")
			sensor_reading = dev.read_line()
			report_temp = round((float(sensor_reading) * 9  / 5 + 32), sensor["accuracy"])

			readings.append(
				{
					"type": sensor["type"],
					"serial_number": sensor["serial_number"],
					"sensor_type": sensor["sensor_type"],
					"sensor_reading": report_temp
				})

			if sensor["is_ref"] is True:
				ref_temp = sensor_reading  # calibration temp for pH

		else:
			# Set reference temperature sensor on the sensor
			dev.send_cmd("T," + str(ref_temp))

			# Get the readings from any Atlas Scientific Elec Conductivity sensors

			if sensor["sensor_type"] == "atlas_scientific_ec":
				# instantiate atlas scientific EC device
				dev = AtlasDevice(sensor["serial_number"])
				dev.send_cmd("R")
				sensor_reading = dev.read_line()
				ppm = sensor_reading.split(',')[1]
				ec = round((float(sensor_reading.split(',')[0]) / 1000), 2)

				readings.append({
						'type': sensor["type"],
						'serial_number': sensor["serial_number"],
						'sensor_type': sensor["sensor_type"],
						'ec': ec,
						'ppm': ppm
					})

			if sensor["sensor_type"] == "atlas_scientific_ph":
				# instantiate atlas scientific EC device
				dev = AtlasDevice(sensor["serial_number"])
				dev.send_cmd("R")
				sensor_reading = round(float(dev.read_line()), 2)

				readings.append({
						'type': sensor["type"],
						'serial_number': sensor["serial_number"],
						'sensor_type': sensor["sensor_type"],
						'sensor_reading': sensor_reading
					})

	return readings


sensors = [{
			# TEMP Atlas Scientific Sensor (also reference temp)
			"sensor_type": "atlas_scientific_temp",
			"type": "hydro-temp",
			"is_ref": True,
			"serial_number": 'DJ00RVZR',
			"accuracy": 2
		}, {
			# pH Atlas Scientific Sensor
			"sensor_type": "atlas_scientific_ph",
			"type": "hydro-ph",
			"is_ref": False,
			"serial_number": 'DJ00RUV8',
			"accuracy": 2
		}, {
			# Atlas Scientific EC Sensor
			"sensor_type": "atlas_scientific_ec",
			"type": "ec",
			"is_ref": False,
			"serial_number": 'DJ00RU96',
			"accuracy": 2,
		}]


read_sensors()


def get_sensor_data():
	read_sensors()