86 lines
2.6 KiB
Python
86 lines
2.6 KiB
Python
# SPDX-FileCopyrightText: 2021 Liz Clark for Adafruit Industries
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#
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# SPDX-License-Identifier: MIT
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import time
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import board
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import adafruit_scd4x
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import sdcardio
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import busio
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import storage
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from adafruit_pcf8523.pcf8523 import PCF8523
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# setup for I2C
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i2c = board.I2C() # uses board.SCL and board.SDA
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# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
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# setup for SCD40
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scd4x = adafruit_scd4x.SCD4X(i2c)
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# setup for RTC
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rtc = PCF8523(i2c)
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# start measuring co2 with SCD40
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scd4x.start_periodic_measurement()
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# list of days to print to the text file on boot
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days = ("Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
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# SPI SD_CS pin
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SD_CS = board.D10
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# SPI setup for SD card
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spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
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sdcard = sdcardio.SDCard(spi, SD_CS)
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vfs = storage.VfsFat(sdcard)
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try:
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storage.mount(vfs, "/sd")
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print("sd card mounted")
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except ValueError:
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print("no SD card")
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# to update the RTC, change set_clock to True
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# otherwise RTC will remain set
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# it should only be needed after the initial set
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# if you've removed the coincell battery
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set_clock = False
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if set_clock:
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# year, mon, date, hour, min, sec, wday, yday, isdst
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t = time.struct_time((2021, 10, 31, 00, 00, 00, 0, -1, -1))
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print("Setting time to:", t)
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rtc.datetime = t
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print()
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# variable to hold RTC datetime
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t = rtc.datetime
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time.sleep(1)
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# initial write to the SD card on startup
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try:
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with open("/sd/co2.txt", "a") as f:
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# writes the date
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f.write('The date is {} {}/{}/{}\n'.format(days[t.tm_wday], t.tm_mday, t.tm_mon, t.tm_year))
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# writes the start time
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f.write('Start time: {}:{}:{}\n'.format(t.tm_hour, t.tm_min, t.tm_sec))
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# headers for data, comma-delimited
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f.write('CO2,Time\n')
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# debug statement for REPL
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print("initial write to SD card complete, starting to log")
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except ValueError:
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print("initial write to SD card failed - check card")
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while True:
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try:
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# variable for RTC datetime
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t = rtc.datetime
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# append SD card text file
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with open("/sd/co2.txt", "a") as f:
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# read co2 data from SCD40
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co2 = scd4x.CO2
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# write co2 data followed by the time, comma-delimited
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f.write('{},{}:{}:{}\n'.format(co2, t.tm_hour, t.tm_min, t.tm_sec))
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print("data written to sd card")
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# repeat every 30 seconds
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time.sleep(30)
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except ValueError:
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print("data error - cannot write to SD card")
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time.sleep(10)
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