sensor.py

# Copyright (C) 2016 Synapse Wireless, Inc.
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# to you to freely modify, redistribute or include this SNAPpy code in any program. The purpose of this code is to help
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"""
Example SNAPpy script for Data Collector sensors.

Returns:
  * Number of polls received since last restart
  * ATmega128RFA1 internal temperature in deci-degrees Celsius (dC)
  * ATmega128RFA1 power supply voltage in milliVolts (mV)
  * ADC Reading from external thermistor.
  * 0-99 reading for light level from photocell.

Also blinks an led each time it is polled.
"""

from snappyatmega.sensors import *
from snappyatmega.utils import adcRefSelect

GPIO_12 = 25
GPIO_18_ADC = 7
GPIO_11_ADC = 0

# Setting this to none will disable the blink
# LED_PIN = None

# 6 is GPIO_1 for SN-171 protoboards and SN-132 paddleboards,
# and the green led on SS200 / SN220 SNAPsticks.
LED_PIN = 6

NUM_POLLS = 0

thermisterAdcChannel = GPIO_18_ADC

photoCellPin = GPIO_12
photoCellAdcChannel = GPIO_11_ADC
requiredRange = 100
photoMax = 0x0000
photoMin = 0x03FF


def data():
    """Return the formatted data string"""
    # First, blink the LED
    pulsePin(LED_PIN, 1000, True)

    # Get the individual values
    num_polls = _get_poll_counter()

    raw_temp = atmega_temperature_read_raw()
    temp_dC = atmega_temperature_raw_to_dC(raw_temp)

    ps_mV = atmega_ps_voltage()

    ext_temp = readAdc(thermisterAdcChannel)

    photo_val = _read_photo()

    # Return as a CSV-formatted string
    return str(num_polls) + "," + str(temp_dC) + "," + str(ps_mV) + ',' + str(ext_temp) + ',' + str(photo_val)


@setHook(HOOK_STARTUP)
def _on_startup():
    # Initialize the LED
    setPinDir(LED_PIN, True)
    writePin(LED_PIN, False)

    _reset_poll_counter()
    _init_ext_sensors()


def _reset_poll_counter():
    """Reset the poll counter"""
    global NUM_POLLS
    NUM_POLLS = 0


def _init_ext_sensors():
    # Set up thermistor
    readAdc(thermisterAdcChannel)
    adcRefSelect(18)  # Force 1.8v ADC REF (default is 1.6v)

    # Set up photocell
    setPinDir(photoCellPin,True)
    writePin(photoCellPin, True) # Set the pin high to power the device
    _read_photo()  # take an initial reading to get things started


@setHook(HOOK_1S)
def _read_photo():
    """Get darkness value from photo cell reading, scaled 0-99"""
    global photoMax, photoMin

    # Sample the photocell
    curReading = readAdc(photoCellAdcChannel)

    # Auto-Calibrate min/max photocell readings
    if photoMax < curReading:
        photoMax = curReading
    if photoMin > curReading:
        photoMin = curReading

    if photoMax <= photoMin:
        return 0

    photoRange = photoMax - photoMin
    if photoRange < requiredRange:  # if not yet calibrated
        return 0

    # Remove zero-offset to get value in range 0-1024 (10-bit ADC)
    curReading -= photoMin

    # Scale 0-100, careful not to exceed 16-bit integer positive range (32768)
    curReading = (curReading * 10) / (photoRange / 10)

    # Return value scaled 0-99
    return (curReading * 99) / 100


def _get_poll_counter():
    """Increment and return the poll counter"""
    global NUM_POLLS
    NUM_POLLS += 1

    return NUM_POLLS