Cameteo/circuitpython/code/main.py

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

"""
##########################
# Weather and GPS logger #
##########################
Author : Pierrick Couturier

Use with:
 * Adafruit Feather M0 Express (CircuitPython firmware 3.0.0)
 * Adafruit Ultimate GPS FeatherWing
 * Bosch BME280 sensor (air temperature, humidity, atmospheric pressure) on I2C

https://framagit.org/arofarn/Cameteo

TODO for v1 :
 * write data on flash drive (work-in-progress)
 * send data through UART (work-in-progress)
"""
__version__ = 0.2

##########
# config #
##########
print_data = True        # Print data on USB UART / REPL output ?
send_json_data = True    # Send data as JSON on second UART ?
backup_data = True       # Write data as CSV files on onboard SPI Flash ?
data_to_neopixel = True  # Display atmospheric data as color on onboard neopixel ?
gps_enable = True        # Use GPS module ?
update_interval = const(10)   # Interval between data acquisition (in seconds)
datetime_format = "{:04}/{:02}/{:02}_{:02}:{:02}:{:02}"     # Date/time format
neopixel_max_value =const(70) #max value instead of brightness to spare some mem

#######################

import microcontroller
import gc, os
# import micropython
import time, rtc
from busio import I2C, UART
from analogio import AnalogIn
from digitalio import DigitalInOut, Direction

from adafruit_bme280 import Adafruit_BME280_I2C
from adafruit_gps import GPS
import neopixel

###########
# Classes #
###########

class Data:
    """Class for handling data"""
    def __init__(self):
        self.data = {'SYS': {'time': "2000/01/01_00:00:00",
                             'vbat': int(),
                             'cput': float()},
                     'BME': {'temp': float(),
                             'hum':  int(),
                             'press': float()},
                     'GPS': {'time': "2000/01/01_00:00:00",
                             'lat': float(),
                             'lon': float(),
                             'alt': float(),
                             'qual': int()}
                     }

    def update(self):
        """Read the data from various sensors and update the data dict variable"""
        #Data from Feather board
        self.data['SYS']['time'] = datetime_format.format(*clock.datetime[0:6])
        self.data['SYS']['vbat'] = round(measure_vbat(), 3)
        self.data['SYS']['cput'] = round(microcontroller.cpu.temperature, 2)

        #Data from BME280
        self.data['BME']['temp'] = round(bme280.temperature, 1)
        self.data['BME']['hum'] = int(bme280.humidity)
        self.data['BME']['press'] = round(bme280.pressure, 2)

        if gps_enable:
            if gps.has_fix:
                self.data['GPS']['time'] = datetime_format.format(gps.timestamp_utc.tm_year,
                                                                  gps.timestamp_utc.tm_mon,
                                                                  gps.timestamp_utc.tm_mday,
                                                                  gps.timestamp_utc.tm_hour,
                                                                  gps.timestamp_utc.tm_min,
                                                                  gps.timestamp_utc.tm_sec)
                self.data['GPS']['lat'] = gps.latitude
                self.data['GPS']['lon'] = gps.longitude
                self.data['GPS']['alt'] = gps.altitude_m
                self.data['GPS']['qual'] = gps.fix_quality
            else:
                self.data['GPS']['lat'] = None
                self.data['GPS']['lon'] = None
                self.data['GPS']['alt'] = None
        else:
            self.data['GPS'] = None

    def show(self):
            """Serialize data for visualization on serial console"""
            for source in self.data.keys():
                print(source + ": ")
                if not self.data[source] == None:
                    for d in self.data[source].items():
                        print("\t{0}: {1}".format(d[0], d[1]))

    @property
    def json(self):
        """Serialized data to compact json-formatted string"""
        output = '{'
        first_source = True
        for source in self.data.keys():
            if first_source:
                first_source = False
                comma_src = ""
            else:
                comma_src = ","
            output = '{}{}"{}":'.format(output, comma_src, source)
            if not self.data[source] == None:
                output = output + '{'
                first_data = True
                for d in self.data[source].items():
                    if first_data:
                        comma = ""
                        first_data = False
                    else:
                        comma = ","
                    output = '{}{}"{}":"{}"'.format(output, comma, d[0], d[1])
            output = output + '}'
        output = output + '}'
        return output

    @property
    def rgb(self):
        """Convert atmospheric data from BME280 sensor into NeoPixel color as
        a tuple (RED, BLUE, GREEN):
         * RED => temperature : max = 35degC, min =10degC (range 25°C)
         * BLUE => humidity : max= 100%, mini=0%
         * GREEN => pression : mini=960hPa, maxi = 1030hPa (range 70hPa)
        """
        # RED componant calculation from temperature data
        # 10 is the min temperature, 25 is the range
        # (10+25=35°C = max temperature)
        red = int((self.data['BME']['temp']-10)*neopixel_max_value/25)
        if red > neopixel_max_value:
            red = neopixel_max_value
        if red < 0:
            red = 0

        # BLUE componant calculation: very simple! By definition relative
        #  humidity cannot be more than 100 or less than 0, physically
        blue = int(self.data['BME']['hum']*neopixel_max_value/100)

        # GREEN component calculation : 960 is the minimum pressure and 70 is
        #  the range (960+70 = 1030hPa = max pressure)
        green = int((self.data['BME']['press']-960)*neopixel_max_value/70)
        if green > neopixel_max_value:
            green = neopixel_max_value
        if green < 0:
            green = 0

        if print_data:
            print("Col:{}".format((red, green, blue)))

        return (red, green, blue)

    def write_on_flash(self):
        """Save the current data as csv file on SPI flash"""
        try:
            with open("data/data.csv", "a") as csv_file:
                csv_file.write("{};{};{};{}\n".format(self.data['SYS']['time'],
                                                      self.data['BME']['temp'],
                                                      self.data['BME']['hum'],
                                                      self.data['BME']['press']))
        except OSError as e:
            print("Err {}: readonly".format(e))
            backup_data = False      #to avoid trying again till next reset
            # Turn onboard led on to indicate read-only error
            led13.value = True

#############
# Functions #
#############

def check_data_dir():
    """Check if data directories exists"""
    if 'data' not in os.listdir():
        os.mkdir('data')
        os.mkdir('data/hourly')
        os.mkdir('data/daily')
    elif 'hourly' not in os.listdir('data'):
        os.mkdir('data/hourly')
    elif 'daily' not in os.listdir('data'):
        os.mkdir('data/daily')

def set_clock_from_GPS(treshold=5.0):
    """Compare internal RTC and date-time from GPS (if enable and fixed) and set
    the RTC date time to GPS date-time if the difference is more or equal to
    threshold (in seconds)"""

    if gps_enable and gps.has_fix:
        #Congreen GPS timestamp into struct_time
        gps_datetime =  time.struct_time((gps.timestamp_utc.tm_year,
                                          gps.timestamp_utc.tm_mon,
                                          gps.timestamp_utc.tm_mday,
                                          gps.timestamp_utc.tm_hour,
                                          gps.timestamp_utc.tm_min,
                                          gps.timestamp_utc.tm_sec, 0, 0, 0))
        #Max difference between GPS and internal RTC (in seconds):
        if abs(time.mktime(gps_datetime) - time.mktime(clock.datetime)) >= treshold:
            print("Clock difference with GPS!")
            print("Previous date/time : " + datetime_format.format(*clock.datetime[0:6]))
            clock.datetime = gps_datetime   #Trust GPS if there is a bias
            print("New date/time : " + datetime_format.format(*clock.datetime[0:6]))

def measure_vbat(samples=10, timestep=0.01):
    """Measure Vbattery as the mean of n samples with timestep second between
    each measurement"""
    # Note about v_bat calculation :
    # 0.000100708 = 2*3.3/65536 with
    #  2 : voltage is divided by 2
    #  3.3 : Vref = 3.3V
    #  65536 : 16bit ADC
    v = 0
    for i in range(samples):
        v = v + vbat.value
        time.sleep(timestep)
    return v/samples*0.000100708

#########
# Setup #
#########

gc.collect()
#micropython.mem_info()

#Enable RTC of the feather M0 board
clock = rtc.RTC()
#clock.datetime = time.struct_time((2018, 7, 29, 15, 31, 30, 0, 0, 0))

# BME280 sensors (I2C)
i2c = I2C(microcontroller.pin.PA23, microcontroller.pin.PA22)
# i2c addresses for BME280 breakout :
#   0x77 = adafruit breakout board
#   0x76 = tiny chinese board
bme280 = Adafruit_BME280_I2C(i2c, address=0x76)

# Battery voltage
vbat = AnalogIn(microcontroller.pin.PA07)

#Set the pin to control the power to GPS module
gps_en_pin = DigitalInOut(microcontroller.pin.PB02)
gps_en_pin.direction = Direction.OUTPUT

#Set the pin N°13 to use the onboard LED as read-only/read-write indicator
led13 = DigitalInOut(microcontroller.pin.PA17)
led13.direction = Direction.OUTPUT
led13.value = False

# Set GPS module on FeatherWing board
gps_en_pin.value = not gps_enable  #Set enable pin high to disable GPS module
if gps_enable:
    gps_uart = UART(microcontroller.pin.PA10, microcontroller.pin.PA11,
                    baudrate=9600, timeout=3000)
    gps = GPS(gps_uart)
    # Turn on the basic GGA and RMC info
    gps.send_command('PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0')
    gps.send_command('PMTK220,1000')    # 1000 ms refresh rate

# Second UART to communicate with raspberry pi (throught GPIO)
if send_json_data:
    rpi_uart = UART(microcontroller.pin.PB10, microcontroller.pin.PB11,
                    baudrate=115200, timeout=2000)

# Set onboard Neopixel : used as atmo data output
#  brightness is fixed to 1 to spare some memory. Use neopixel_max_value instead
if data_to_neopixel:
    pixel = neopixel.NeoPixel(microcontroller.pin.PA06, 1, brightness=1)
else:
    #if neopixel is disable : turn off the LED
    pixel = neopixel.NeoPixel(microcontroller.pin.PA06, 1, brightness=1)
    pixel[0] = (0,0,0)
    pixel = None

#Finally check if data directories exist
check_data_dir()

#############
# Main loop #
#############

#Create the Data object
data = Data()

#Init timer
last_update = time.monotonic()
while True:

    if gps_enable:
        gps.update()

    current = time.monotonic()
    if current - last_update >= update_interval:
        last_update = current
        set_clock_from_GPS()
        data.update()
        if print_data:
            data.show()
        if send_json_data:
            rpi_uart.write(data.json)
        if backup_data:
            data.write_on_flash()
        if data_to_neopixel:
            pixel[0] = data.rgb

        gc.collect()
        # micropython.mem_info(1)
        # print('Memory free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))