class BTMUXcontrol:
def __init__(self):
self.temp = 0
self.output_pins = [24, 25, 26, 27]
self.IOLock = threading.Lock() # mutual lock for R/W control
self.gpio = Gpio() # initialize GPIO controller
# setup output pins
self.IOLock.acquire()
for pin in self.output_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
self.gpio.digitalWrite(pin, self.gpio.LOW)
self.IOLock.release()
def decToBin(self, n):
num = [0, 0, 0, 0]
if n == 0:
return num
else:
for x in range(n):
t = x + 1
for y in range(4):
num[y] = t % 2
t = t / 2
return num
def mux_channel(self, channel):
bin_list = self.decToBin(channel) #binary list
self.IOLock.acquire()
for z in range(4):
self.gpio.digitalWrite(self.output_pins[z], bin_list[z])
self.IOLock.release()
#return True
def read_ADC(self):
self.IOLock.acquire()
raw = int(
open("/sys/bus/iio/devices/iio:device0/in_voltage0_raw").read())
scale = float(
open("/sys/bus/iio/devices/iio:device0/in_voltage_scale").read())
vout = raw * scale
self.IOLock.release()
return vout
class SensorServer(Thread):
"""Sensor server that keeps reading sensors and provide get_sensor_output() method for user"""
def __init__(self, database_name="air_pollution_data.db"):
# Parent class constructor
Thread.__init__(self)
# Assign GPIO pins that controls MUX, LSB to MSB
self.gpio_pins = [24, 25, 26, 27]
self.gpio = Gpio()
# Set GPIO pins to output
try:
for pin in self.gpio_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
except Exception as e:
logger.error("Error setting GPIO pin {}, reason {}".format(
pin, e.message))
# Use A0 port
self.adc_raw = "/sys/bus/iio/devices/iio:device0/in_voltage0_raw"
self.adc_scale = "/sys/bus/iio/devices/iio:device0/in_voltage_scale"
self.sensor_names = ['temp', 'CO', 'NO2', 'SO2', 'O3', 'PM25']
# Use a dict to store sensor output, the format is:
# { "time": [time stamp],
# [sensor1 name]: [sensor1 output],
# ...
# [sensor6 name]: [sensor6 output]}
self.sensor_output = {}
# Create a lock to protect sensor output. That is, when updating the result, lock it on to prevent it from being
# read at the same time; similarly, when reading the result, lock it on to prevent it from being updated.
self.sensor_output_lock = Lock()
# Here we have a decision to make. I decide to let sensor server write sensor outputs to the local database. Of
# course we can do so in a different thread either in a synchronous way or in an asynchronous way. If we do it
# with a synchronous approach, we need to use locks to keep synchronization; if we do it with an asynchronous
# solution, then SQLite3 is already an asynchronous module and I don't see good reason of adding another layer
# of complexity. Perhaps the most reasonable way would be specifying the database in the main thread and then
# send it to the sensor server thread.
self.database_name = database_name
try:
# Create the database file and get the connection object.
self.db_conn = sqlite3.connect(self.database_name)
# Get database cursor from the connection object.
self.db_cur = self.db_conn.cursor()
except Exception as e:
logger.error("Error connecting the database {}, reason: {}".format(
self.database_name, e.message))
self.__del__()
# Create a 'history' table for history data.
# TIME | Temp | SN1 | SN2 | SN3 | SN4 | PM25
# -----------------------------------------------
# int | real | real | real | real | real | real
self.db_cur.execute((
"CREATE TABLE IF NOT EXISTS history (time int PRIMARY KEY NOT NULL,"
" {0} real, {1} real, {2} real, {3} real, {4} real, {5} real)"
).format(self.sensor_names[0], self.sensor_names[1],
self.sensor_names[2], self.sensor_names[3],
self.sensor_names[4], self.sensor_names[5]))
# Commit the changes. When a database is accessed by multiple connections, and one of the processes modifies the
# database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies
# how long the connection should wait for the lock to go away until raising an exception. The default for the
# timeout parameter is 5.0 (five seconds).
self.db_conn.commit()
def __del__(self):
# Gracefully close the database connection.
self.db_conn.close()
# Reset GPIOs.
for i in xrange(0, 4):
self.gpio.digitalWrite(24 + i, Gpio.LOW)
def get_sensor_output(self):
# Get the latest sensor output
return self.sensor_output.copy()
def set_mux_channel(self, m):
# Set MUX channel
# Convert n into a binary string
bin_repr = "{0:04b}".format(m)
# Assign value to pin
for i in xrange(0, 4):
self.gpio.digitalWrite(24 + i, bin_repr[i])
def read_sensor(self, n):
# Read raw data from sensor n, we allocate 2 channels for each sensor:
# sensor 0: channel 0, 1
# sensor 1: channel 2, 3
# ...
# sensor 7: channel 15, 16
# Set MUX to read the first channel
try:
self.set_mux_channel(2 * n)
# Wait for 50 ms
sleep(0.05)
v1 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
# Set MUX to read the second channel
self.set_mux_channel(2 * n + 1)
sleep(0.05)
v2 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
return v1, v2
except Exception as e:
logger.error("Error reading sensor {}, reason: {}".format(
n, e.message))
return 0.0, 0.0
def run(self):
try:
# Create the database file and get the connection object.
self.db_conn = sqlite3.connect(self.database_name)
# Get database cursor from the connection object.
self.db_cur = self.db_conn.cursor()
except Exception as e:
logger.error("Error connecting the database {}, reason: {}".format(
self.database_name, e.message))
self.__del__()
# Keep reading sensors.
while True:
# Acquire the lock
self.sensor_output_lock.acquire()
# Add time stamp
epoch_time = int(time())
self.sensor_output['time'] = epoch_time
# Do sensor reading here
# 1. set MUX to sensor 0, read sensor 0;
# 2. set MUX to sensor 1, read sensor 1;
# ...
# n. set MUX to sensor n - 1, read sensor n - 1.
logger.info("Reading {} sensor...".format(self.sensor_names[0]))
# Temperature constant
t0 = 550
c0, c1 = self.read_sensor(0)
temp = (1.22 * c0) - t0
# Channel 1 is not connected so we don't care about its output
logger.info("{} sensor outputs {} degree".format(
self.sensor_names[0], temp))
# Save output to the dict
self.sensor_output[self.sensor_names[0]] = temp
logger.info("Reading {} sensor...".format(self.sensor_names[1]))
c2, c3 = self.read_sensor(1)
sn1 = (((1.22 * c2) - 345) -
((0.03) * ((1.22 * c3) - ((1.22 * c3) - 314)))) * 3.42465753
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[1], sn1))
# Save output to the dict
self.sensor_output[self.sensor_names[1]] = sn1
logger.info("Reading {} sensor...".format(self.sensor_names[2]))
c4, c5 = self.read_sensor(2)
sn2 = (((1.22 * c4) - 287) - ((1.18) * (1.22 * c5) -
((1.22 * c5) - 292))) * 3.87596899
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[2], sn2))
# Save output to the dict
self.sensor_output[self.sensor_names[2]] = sn2
logger.info("Reading {} sensor...".format(self.sensor_names[3]))
c6, c7 = self.read_sensor(3)
sn3 = (((1.22 * c6) - 333) - ((1.15) * (1.22 * c7) -
((1.22 * c7) - 274))) * 3.47222222
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[3], sn3))
# Save output to the dict
self.sensor_output[self.sensor_names[3]] = sn3
logger.info("Reading {} sensor...".format(self.sensor_names[4]))
c8, c9 = self.read_sensor(4)
sn4 = (((1.22 * c8) - 418) - ((0.18) * (1.22 * c9) -
((1.22 * c9) - 404))) * 2.54452926
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[4], sn4))
# Save output to the dict
self.sensor_output[self.sensor_names[4]] = sn4
logger.info("Reading {} sensor...".format(self.sensor_names[5]))
c10, c11 = self.read_sensor(5)
pm25 = 0.518 + 0.00274 * (240.0 * (1.22 * c10)**6 - 2491.3 *
(1.22 * c10)**5 + 9448.7 *
(1.22 * c10)**4 - 14840.0 *
(1.22 * c10)**3 + 10684.0 *
(1.22 * c10)**2 + 2211.8 *
(1.22 * c10) + 7.9623)
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[5], pm25))
# Save output to the dict
self.sensor_output[self.sensor_names[5]] = pm25
self.db_cur.execute(
"INSERT INTO history VALUES ({}, {}, {}, {}, {}, {}, {})".
format(epoch_time, temp, sn1, sn2, sn3, sn4, pm25))
self.db_conn.commit()
self.sensor_output_lock.release()
# Idle for 3 seconds
sleep(1.8)
class SensorServer(Thread):
"""Sensor server that keeps reading sensors and provide get_sensor_output() method for user"""
def __init__(self):
# Parent class constructor
Thread.__init__(self)
# Assign GPIO pins that controls MUX, LSB to MSB
self.gpio_pins = [24, 25, 26, 27]
self.gpio = Gpio()
# Set GPIO pins to output
try:
for pin in self.gpio_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
except Exception as e:
logger.error("Error setting GPIO pin, reason %s" % e.message)
print "Error setting GPIO pin %d, reason %s" % e.message
# Use A0 port
self.adc_raw = "/sys/bus/iio/devices/iio:device0/in_voltage0_raw"
self.adc_scale = "/sys/bus/iio/devices/iio:device0/in_voltage_scale"
self.sensor_names = ['Temp', 'SN1', 'SN2', 'SN3', 'SN4', 'PM25']
# Use a dict to store sensor output, the format is:
# { "time": [time stamp],
# [sensor1 name]: [sensor1 output],
# ...
# [sensor6 name]: [sensor6 output]}
self.sensor_output = {}
# Create a lock to protect sensor output. That is, when updating the result, lock it on to prevent it from being
# read at the same time; similarly, when reading the result, lock it on to prevent it from being updated.
self.sensor_output_lock = Lock() #스레드의 값이 이상하게 나오는 것을 막기 위해 Lock()
self.db_conn = sqlite3.connect("air_pollution_data.db")
self.db_cur = self.db_conn.cursor()
for sensor_name in self.sensor_names:
self.db_cur.execute(
"CREATE TABLE IF NOT EXISTS %s (time int PRIMARY KEY NOT NULL, value real)"
% sensor_name)
def get_sensor_output(self):
# Get the latest sensor output
return self.sensor_output.copy()
def set_mux_channel(self, m):
# Set MUX channel
# Convert n into a binary string
bin_repr = "{0:04b}".format(m)
# Assign value to pin
for i in xrange(0, 4):
self.gpio.digitalWrite(24 + i, bin_repr[i])
def read_sensor(self, n):
# Read raw data from sensor n, we allocate 2 channels for each sensor:
# sensor 0: channel 0, 1
# sensor 1: channel 2, 3
# ...
# sensor 7: channel 15, 16
# Set MUX to read the first channel
try:
self.set_mux_channel(2 * n)
v1 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
# Set MUX to read the second channel
self.set_mux_channel(2 * n + 1)
v2 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
return v1, v2
except Exception as e:
logger.error("Error reading sensor %d, reason: %s" %
(n, e.message))
print "Error reading sensor %d, reason: %s" % (n, e.message)
return 0.0, 0.0
def run(self):
# Keep reading sensors
while True:
# Acquire the lock
self.sensor_output_lock.acquire()
# Add time stamp
self.sensor_output['time'] = int(time())
# Do sensor reading here
# 1. set MUX to sensor 1, read sensor 1;
# 2. set MUX to sensor 2, read sensor 2;
# ...
# n. set MUX to sensor n, read sensor n.
for i in xrange(0, 6):
logger.info("Reading %s sensor..." % self.sensor_names[i])
print "Reading %s sensor..." % self.sensor_names[i]
v1, v2 = self.read_sensor(i)
self.sensor_output[self.sensor_names[i]] = v1 - v2
self.sensor_output_lock.release()
# Idle for 3 seconds
sleep(3)
gpiopins = [8, 9, 10, 11]
gpio = Gpio()
pinnum = [0, 0, 0, 0]
# Set GPIO pins to output
# try:
# for pin in gpiopins:
# gpio.pinMode(pin, gpio.OUTPUT)
# except Exception as e:
# logger.error("Error : GPIO pin {} .reason {}".format(pin, e.message))
# Blink example
for i in range(4):
neo.pinMode(gpiopins[i], neo.OUTPUT)
while True:
for client_handler in server.active_client_handlers.copy():
# C0
raw, scale = contol_mux(0, 0, 0, 0)
sleep(0.05)
v = raw * scale
t = (v - 500) / 10 - 6
t = (t * 1.8) + 32
print("Temp: {} F ".format(t))
# C1= NO2_WE
raw, scale = contol_mux(0, 0, 1, 0)
sleep(0.05)
from neo import Gpio # import Gpio library from time import sleep # import sleep to wait for blinks neo = Gpio() #create new Neo object pinOne = 25 #pin to use neo.pinMode(pinOne, neo.OUTPUT)# Use innerbank pin 2 and set it as output either 0 (neo.INPUT) or 1 (neo.OUTPUT) #Blink example while True: #Do for five times neo.digitalWrite(pinOne,neo.HIGH) #write high value to pin sleep(1)# wait one second neo.digitalWrite(pinOne,neo.LOW) #write low value to pin sleep(1)# wait one second
def getSamsungCode(self):
# Learning mode feedback led
pinLED = 26
# IR receiver
pinIR = 25
command_length_samasung = 65
neo = Gpio()
neo.pinMode(pinIR, neo.INPUT)
neo.pinMode(pinLED, neo.OUTPUT)
neo.digitalWrite(pinLED, neo.HIGH)
sample_number = 0
# Compute the average result after MAX_SAMPLES
bits_sum = [0] * 32
MAX_SAMPLES = 3
while True:
# stop the receiver after MAX_SAMPLES
if sample_number == MAX_SAMPLES:
for x in range(0, len(bits_sum)):
bits_sum[x] = bits_sum[x] / (MAX_SAMPLES * 1.0)
break
value = 1
# Loop until get IR data
time_to_live = 45000
while value and time_to_live:
value = neo.digitalRead(pinIR)
time_to_live -= 1
if time_to_live == 0:
neo.digitalWrite(pinLED, neo.LOW)
return ""
# Grab the start time of the command
startTime = datetime.now()
# Used to buffer the command pulses
command = []
# The end of the "command" happens when we read more than
# a certain number of 1s (1 is off for the IR receiver)
numOnes = 0
# Used to keep track of transitions from 1 to 0
previousVal = 0
while True:
if value != previousVal:
# The value has changed, so calculate the length of this run
now = datetime.now()
pulseLength = now - startTime
startTime = now
command.append((previousVal, pulseLength.microseconds))
# print str(previousVal) + " " + str(pulseLength.microseconds)
#if len(command) == command_length_samasung:
# break
if value:
numOnes = numOnes + 1
else:
numOnes = 0
if numOnes > 100:
break
#if numOnes > 300:
# break
previousVal = value
value = neo.digitalRead(pinIR)
# A Sony IR signal starts with 2400 microseconds on and 600 microseconds off;
# that's the first wide pulse. A "1" bit is transmitted with 1200 microseconds on and 600 microseconds off,
# while a "0" bit is transmitted with 600 microseconds on and 600 microseconds off.
# (This encoding is also called SIRC or SIRCS encoding.)
# Chop the header of the received IR signal
# print command
command = command[2:]
command = command[:64]
#print "Command length: " + str(len(command))
# Establish the payload of the received IR signal
binaryString = "".join(
map(lambda x: "1" if x[1] > 1080 else "0",
filter(lambda x: x[0] == 1, command)))
# The length of the payload, according to SONY protocol is 12 bits; skip otherwise
#print len(binaryString)
if len(binaryString) != 32:
continue
#print "Good length!"
sample_number = sample_number + 1
binaryString = map(int, binaryString)
bits_sum = [sum(x) for x in zip(bits_sum, binaryString)]
# compute the IR code based on MAX_SAMPLES
result = ""
for x in bits_sum:
if x < 0.5:
result += '0'
else:
result += '1'
neo.digitalWrite(pinLED, neo.LOW)
print result
return result
class Reader:
# S0,S1,S2,S3
selector_pins = [8, 9, 10, 11]
# Number of connected to MUX Board
mux_channel = {
'temp1': 0,
'no2': {
'we': 1,
'ae': 2
},
'o3': {
'we': 3,
'ae': 4
},
'co': {
'we': 5,
'ae': 6
},
'so2': {
'we': 7,
'ae': 8
},
'pm2_5': 9,
}
# Refer to 25-000160 Alphasense Datasheet
calibration = {
'no2': {
'n': [1.18, 1.18, 1.18, 1.18, 1.18, 1.18, 1.18, 2.00],
'we_zero': 295,
'ae_zero': 282,
'sensitivity': 0.228
},
'o3': {
'n': [0.18, 0.18, 0.18, 0.18, 0.18, 0.18, 0.18, 0.18],
'we_zero': 391,
'ae_zero': 390,
'sensitivity': 0.399
},
'co': {
'n': [1.40, 1.03, 0.85, 0.62, 0.30, 0.03, -0.25, -0.48],
'we_zero': 347,
'ae_zero': 296,
'sensitivity': 0.267
},
'so2': {
'n': [0.85, 0.85, 0.85, 0.85, 0.85, 1.15, 1.45, 1.75],
'we_zero': 345,
'ae_zero': 255,
'sensitivity': 0.318
}
}
def __init__(self):
self.lock = threading.Lock()
self.gpio = Gpio()
# init to LOW
self.lock.acquire()
for pin in Reader.selector_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
self.gpio.digitalWrite(pin, self.gpio.LOW)
self.lock.release()
# Read NO2, SO2, O3, CO, PM2.5, TEMP
def read_no2(self): # Had a problem on sensors
return round(self.__calibrate('no2') * 1000, 2)
def read_o3(self):
return round(self.__calibrate('o3') * 100, 2)
def read_co(self):
return round(self.__calibrate('co'), 2)
def read_so2(self):
return round(self.__calibrate('so2') * 1000, 2)
def read_temp(self):
mV = self.__read_adc(Reader.mux_channel['temp1'])
temp = (mV - 500) * 0.1 # Celcius Value
ftemp = (temp * 1.8) + 32 # Celcius to Fahrenheit
return round(ftemp, 2)
def read_pm(self):
mV = self.__read_adc(Reader.mux_channel['pm2_5'])
v = mV / 1000
hppcf = 240 * (v**6) - 2491.3 * (v**5) + 9448.7 * (v**4) - 14840 * (
v**3) + 10684 * (v**2) + 2211.8 * v + 7.9623
ugm3 = .518 + .00274 * hppcf
return round(ugm3, 3)
def __read_adc(self, channel):
s_bin = self.__dec_to_bin(channel)
self.lock.acquire()
# write
for i in range(4):
self.gpio.digitalWrite(Reader.selector_pins[i], s_bin[i])
# read
raw = int(
open("/sys/bus/iio/devices/iio:device0/in_voltage0_raw").read())
scale = float(
open("/sys/bus/iio/devices/iio:device0/in_voltage_scale").read())
self.lock.release()
return raw * scale
def __calibrate(self, name):
we = self.__read_adc(Reader.mux_channel[name]['we'])
ae = self.__read_adc(Reader.mux_channel[name]['ae'])
temperature = self.read_temp()
calibration = Reader.calibration[name]
we = we - calibration['we_zero']
ae = ae - calibration['ae_zero']
temp = int(temperature / 10) + 3
if temp > 7:
temp = 7
ae = (calibration['n'][temp]) * ae
we = (we - ae) / calibration['sensitivity']
if we / 1000 > 0:
return we / 1000
else:
return 0
def __dec_to_bin(self, n):
num = [0, 0, 0, 0]
if n == 0:
return num
else:
for x in range(n):
t = x + 1
for y in range(4):
num[y] = t % 2
t = t / 2
return num
# A easy Gpio library example for the Udoo Neo created by David Smerkous
# The current things this library can do
# digitalWriting/Reading - Soon to come PWM
from neo import Gpio # import Gpio library
from time import sleep # import sleep to wait for blinks
neo = Gpio() #create new Neo object
pinTwo = 2 #pin to use
pinThree = 3
neo.pinMode(pinTwo, neo.OUTPUT)# Use innerbank pin 2 and set it as output either 0 (neo.INPUT) or 1 (neo.OUTPUT)
neo.pinMode(pinThree, neo.INPUT)# Use pin three(innerbank) and read set state to read
#Blink example
for a in range(0, 5): #Do for five times
neo.digitalWrite(pinTwo,neo.HIGH) #write high value to pin
sleep(1)# wait one second
neo.digitalWrite(pinTwo,neo.LOW) #write low value to pin
sleep(1)# wait one second
#Read pin
print "Current pin("+str(pinThree)+") state is: "+str(neo.digitalRead(pinThree)) # read current value of pinThree(To succesfully read a pin it must be either pulled to ground or 3.3v, a non connected wire will not work)
def getCode(self):
# Learning mode feedback led
pinLED = 26
# IR receiver
pinIR = 25
neo = Gpio()
neo.pinMode(pinIR, neo.INPUT)
neo.pinMode(pinLED, neo.OUTPUT)
neo.digitalWrite(pinLED, neo.HIGH)
# Compute the average result after MAX_SAMPLES
gap_number = 0
MAX_GAPS = 3
GAP_TIME = 20000
value = 1
time_to_live = 45000
while value and time_to_live:
value = neo.digitalRead(pinIR)
time_to_live -= 1
if time_to_live == 0:
neo.digitalWrite(pinLED, neo.LOW)
return ""
# Grab the start time of the command
startTime = datetime.now()
# Used to buffer the command pulses
command = []
# Used to keep track of transitions from 1 to 0
previousVal = 0
while True:
if value != previousVal:
# The value has changed, so calculate the length of this run
now = datetime.now()
pulseLength = now - startTime
startTime = now
if pulseLength.microseconds > GAP_TIME:
gap_number = gap_number + 1
if gap_number == MAX_GAPS:
break
command.append((previousVal, pulseLength.microseconds))
previousVal = value
value = neo.digitalRead(pinIR)
neo.digitalWrite(pinLED, neo.LOW)
result = ""
for (i, j) in command:
result = result + " " + str(j)
#result = result.replace(",", "")
result = result[1:]
print result
return result
epoch_time = int(time()) # epoch time
neo = Gpio()
S0 = 8 # pin to use
S1 = 9
S2 = 10
S3 = 11
pinNum = [S0, S1, S2, S3]
num = [0, 0, 0, 0]
# Blink example
for i in range(4):
neo.pinMode(pinNum[i], neo.OUTPUT)
#Temperature sensor
neo.digitalWrite(pinNum[0], 0)
neo.digitalWrite(pinNum[1], 0)
neo.digitalWrite(pinNum[2], 0)
neo.digitalWrite(pinNum[3], 0)
sleep(0.05)
raw = int(
open(
"/sys/bus/iio/devices/iio:device0/in_voltage0_raw").read())
scale = float(
open("/sys/bus/iio/devices/iio:device0/in_voltage_scale").read(
))
c0 = raw * scale
class SensorServer(Thread):
"""Sensor server that keeps reading sensors and provide get_sensor_output() method for user"""
def __init__(self, database_name="air_pollution_data.db"):
# Parent class constructor
Thread.__init__(self)
# Assign GPIO pins that controls MUX, LSB to MSB
self.gpio_pins = [24, 25, 26, 27]
self.gpio = Gpio()
# Set GPIO pins to output
try:
for pin in self.gpio_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
except Exception as e:
logger.error("Error setting GPIO pin {}, reason {}".format(
pin, e.message))
# Use A0 port
self.adc_raw = "/sys/bus/iio/devices/iio:device0/in_voltage0_raw"
self.adc_scale = "/sys/bus/iio/devices/iio:device0/in_voltage_scale"
self.sensor_names = ['Temp', 'SN1', 'SN2', 'SN3', 'SN4', 'PM25']
# Use a dict to store sensor output, the format is:
# { "time": [time stamp],
# [sensor1 name]: [sensor1 output],
# ...
# [sensor6 name]: [sensor6 output]}
self.sensor_output = {}
# Create a lock to protect sensor output. That is, when updating the result, lock it on to prevent it from being
# read at the same time; similarly, when reading the result, lock it on to prevent it from being updated.
self.sensor_output_lock = Lock()
# Here we have a decision to make. I decide to let sensor server write sensor outputs to the local database. Of
# course we can do so in a different thread either in a synchronous way or in an asynchronous way. If we do it
# with a synchronous approach, we need to use locks to keep synchronization; if we do it with an asynchronous
# solution, then SQLite3 is already an asynchronous module and I don't see good reason of adding another layer
# of complexity. Perhaps the most reasonable way would be specifying the database in the main thread and then
# send it to the sensor server thread.
self.database_name = database_name
try:
# Create the database file and get the connection object.
self.db_conn = sqlite3.connect(self.database_name)
# Get database cursor from the connection object.
self.db_cur = self.db_conn.cursor()
except Exception as e:
logger.error("Error connecting the database {}, reason: {}".format(
self.database_name, e.message))
self.__del__()
# Create tables for each sensors. Each table consists a time stamp key (epoch time) in integer and a real value
# to hold the result of the sensor. Create tables only if they are not exist.
for sensor_name in self.sensor_names:
self.db_cur.execute(
"CREATE TABLE IF NOT EXISTS {} (time int PRIMARY KEY NOT NULL, value real)"
.format(sensor_name))
# Commit the changes. When a database is accessed by multiple connections, and one of the processes modifies the
# database, the SQLite database is locked until that transaction is committed. The timeout parameter specifies
# how long the connection should wait for the lock to go away until raising an exception. The default for the
# timeout parameter is 5.0 (five seconds).
self.db_conn.commit()
def __del__(self):
# Gracefully close the database connection.
self.db_conn.close()
# Reset GPIOs.
for i in xrange(0, 4):
self.gpio.digitalWrite(24 + i, Gpio.LOW)
def get_sensor_output(self):
# Get the latest sensor output
return self.sensor_output.copy()
def set_mux_channel(self, m):
# Set MUX channel
# Convert n into a binary string
bin_repr = "{0:04b}".format(m)
# Assign value to pin
for i in xrange(0, 4):
self.gpio.digitalWrite(24 + i, bin_repr[i])
def read_sensor(self, n):
# Read raw data from sensor n, we allocate 2 channels for each sensor:
# sensor 0: channel 0, 1
# sensor 1: channel 2, 3
# ...
# sensor 7: channel 15, 16
# Set MUX to read the first channel
try:
self.set_mux_channel(2 * n)
# Wait for 50 ms
sleep(0.05)
v1 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
# Set MUX to read the second channel
self.set_mux_channel(2 * n + 1)
sleep(0.05)
v2 = int(open(self.adc_raw).read()) * float(
open(self.adc_scale).read())
return v1, v2
except Exception as e:
logger.error("Error reading sensor {}, reason: {}".format(
n, e.message))
return 0.0, 0.0
def run(self):
try:
# Create the database file and get the connection object.
self.db_conn = sqlite3.connect(self.database_name)
# Get database cursor from the connection object.
self.db_cur = self.db_conn.cursor()
except Exception as e:
logger.error("Error connecting the database {}, reason: {}".format(
self.database_name, e.message))
self.__del__()
# Keep reading sensors.
while True:
# Acquire the lock
self.sensor_output_lock.acquire()
# Add time stamp
epoch_time = int(time())
self.sensor_output['time'] = epoch_time
# Do sensor reading here
# 1. set MUX to sensor 0, read sensor 0;
# 2. set MUX to sensor 1, read sensor 1;
# ...
# n. set MUX to sensor n - 1, read sensor n - 1.
logger.info("Reading {} sensor...".format(self.sensor_names[0]))
# Temperature constant
t0 = 550
c0, c1 = self.read_sensor(0)
# Channel 1 is not connected so we don't care about its output
temperature = c0 - t0
logger.info("{} sensor outputs {} degree".format(
self.sensor_names[0], temperature))
# Save output to the dict
self.sensor_output[self.sensor_names[0]] = temperature
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[0], epoch_time, temperature))
logger.info("Reading {} sensor...".format(self.sensor_names[1]))
c2, c3 = self.read_sensor(1) # NO2
output = ((c2 - 0.215) - (1.35) * (c3 - 0.246)) / (-0.212)
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[1], output))
# Save output to the dict
self.sensor_output[self.sensor_names[1]] = output
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[1], epoch_time, output))
logger.info("Reading {} sensor...".format(self.sensor_names[2]))
c4, c5 = self.read_sensor(2) # O3
output = ((c4 - 0.39) - (1.28) * (c5 - 0.393)) / (-0.276)
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[2], output))
# Save output to the dict
self.sensor_output[self.sensor_names[2]] = output
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[2], epoch_time, output))
logger.info("Reading {} sensor...".format(self.sensor_names[3]))
c6, c7 = self.read_sensor(3) #CO
output = ((c4 - 0.39) - (1.28) * (c5 - 0.393)) / (-0.276)
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[3], output))
# Save output to the dict
self.sensor_output[self.sensor_names[3]] = output
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[3], epoch_time, output))
logger.info("Reading {} sensor...".format(self.sensor_names[4]))
c8, c9 = self.read_sensor(4) #SO2
output = ((c8 - 0.28) - (1.82) * (c9 - 0.306)) / (-0.296)
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[4], output))
# Save output to the dict
self.sensor_output[self.sensor_names[4]] = output
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[4], epoch_time, output))
logger.info("Reading {} sensor...".format(self.sensor_names[5]))
c10, c11 = self.read_sensor(5)
output = c10 - c11
logger.info("{} sensor outputs {} ppb".format(
self.sensor_names[5], output))
# Save output to the dict
self.sensor_output[self.sensor_names[5]] = output
self.db_cur.execute("INSERT INTO {} VALUES ({}, {})".format(
self.sensor_names[5], epoch_time, output))
self.db_conn.commit()
self.sensor_output_lock.release()
# Idle for 3 seconds
sleep(1.8)
class SensingThread(threading.Thread):
selector_pins = [16, 17, 18, 19]
mux_channel = {
'no2': {
'we': 2,
'ae': 3
},
'o3': {
'we': 4,
'ae': 5
},
'co': {
'we': 6,
'ae': 7
},
'so2': {
'we': 8,
'ae': 9
},
'temp': 0,
'pm2_5': 1,
}
calibration = {
'no2': {
'n': [1.18, 1.18, 1.18, 1.18, 1.18, 1.18, 1.18, 2.00],
'we_zero': 287,
'ae_zero': 292,
'sensitivity': 0.258
},
'o3': {
'n': [0.18, 0.18, 0.18, 0.18, 0.18, 0.18, 0.18, 0.18],
'we_zero': 418,
'ae_zero': 404,
'sensitivity': 0.393
},
'co': {
'n': [1.40, 1.03, 0.85, 0.62, 0.30, 0.03, -0.25, -0.48],
'we_zero': 345,
'ae_zero': 314,
'sensitivity': 0.292
},
'so2': {
'n': [0.85, 0.85, 0.85, 0.85, 0.85, 1.15, 1.45, 1.75],
'we_zero': 333,
'ae_zero': 274,
'sensitivity': 0.288
}
}
read_time = 0.2
def __init__(self, sender):
threading.Thread.__init__(self)
self.sender = sender
self.gpio = Gpio()
# init to LOW
for pin in SensingThread.selector_pins:
self.gpio.pinMode(pin, self.gpio.OUTPUT)
self.gpio.digitalWrite(pin, self.gpio.LOW)
def run(self):
while True:
data = self.__read_all()
print "Raw value : " + str(data)
DBManager.insert_air_data(data)
self.sender.send({"type": "real-time", "data": data})
def __read_all(self):
"""
Read all sensor values
:return: json string of sensor values (temp, so2, no2, co, o3, pm25)
"""
temp = round(self.__read_temp(), 2)
no2 = round(self.__read_no2_ppb(temp), 2)
o3 = round(self.__read_o3_ppb(temp), 2)
co = round(self.__read_co_ppm(temp), 2)
so2 = round(self.__read_so2_ppb(temp), 2)
pm2_5 = round(self.__read_pm2_5(), 2)
timestamp = int(time.time())
return {
'temp': temp,
'no2': no2,
'o3': o3,
'co': co,
'so2': so2,
'pm2_5': pm2_5,
'time': timestamp
}
def __read_temp(self):
channel = SensingThread.mux_channel['temp']
subtotal = 0.0
c = 0
start_time = time.time()
while time.time() - start_time < SensingThread.read_time:
mV = self.__read_adc(channel)
temp = (mV - 500) / 10 - 10
subtotal += temp
c += 1
result = subtotal / c
if result > 50:
result = 50
if result < -20:
result = -20
return result
#return 25
def __read_no2_ppb(self, temp):
return self.__calibrate_op('no2', temp)
def __read_o3_ppb(self, temp):
return self.__calibrate_op('o3', temp)
def __read_co_ppm(self, temp):
return self.__calibrate_op('co', temp) / 1000
def __read_so2_ppb(self, temp):
return self.__calibrate_op('so2', temp)
def __read_pm2_5(self):
subtotal = 0.0
c = 0
start_time = time.time()
while time.time() - start_time < SensingThread.read_time:
v = self.__read_adc(SensingThread.mux_channel['pm2_5']) / 1000
hppcf = 240.0 * (v**6) - 2491.3 * (v**5) + 9448.7 * (
v**4) - 14840.0 * (v**3) + 10684.0 * (v**
2) + 2211.8 * v + 7.9623
subtotal += .518 + .00274 * hppcf
c += 1
return subtotal / c
def __calibrate_op(self, name, temp):
channel_we = SensingThread.mux_channel[name]['we']
channel_ae = SensingThread.mux_channel[name]['ae']
calibration = SensingThread.calibration[name]
zero_we = calibration['we_zero']
zero_ae = calibration['ae_zero']
subtotal = 0.0
c = 0
start_time = time.time()
while time.time() - start_time < SensingThread.read_time:
we = self.__read_adc(channel_we)
ae = self.__read_adc(channel_ae)
we = we - zero_we
ae = ae - zero_ae
if temp > 50:
temp = 50
elif temp < -20:
temp = -20
ae = (calibration['n'][int(temp / 10) + 2]) * ae
we = (we - ae) / calibration['sensitivity']
subtotal += we if we > 0 else 0
c += 1
# ppb
return subtotal / c
def __read_adc(self, channel):
s_bin = self.__dec_to_bin(channel)
# write
for i in range(4):
self.gpio.digitalWrite(SensingThread.selector_pins[i], s_bin[i])
# read
raw = int(
open("/sys/bus/iio/devices/iio:device0/in_voltage0_raw").read())
scale = float(
open("/sys/bus/iio/devices/iio:device0/in_voltage_scale").read())
return raw * scale
def __dec_to_bin(self, n):
num = [0, 0, 0, 0]
if n == 0:
return num
else:
for x in range(n):
t = x + 1
for y in range(4):
num[y] = t % 2
t = t / 2
return num
from neo import Gpio
from time import sleep
neo = Gpio()
pinNum = [0, 1, 2, 3]
for i in pinNum:
neo.pinMode(pinNum[i], neo.OUTPUT)
for x in range(15):
num = [0, 0, 0, 0]
t = x + 1
for y in range(4):
num[y] = t % 2
t = t / 2
neo.digitalWrite(pinNum[3], num[3])
neo.digitalWrite(pinNum[2], num[2])
neo.digitalWrite(pinNum[1], num[1])
neo.digitalWrite(pinNum[0], num[0])
sleep(1)