data-analytics/data-dash/pi/run.py

#!/usr/bin/python
# Copyright 2024 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import time

from google.cloud import bigtable
from mfrc522 import SimpleMFRC522
import RPi.GPIO as GPIO

from beam_break_sensor import BeamBreakSensor
from side_controller import SideController

# Pins as mapped to the Pis
PINS = [i for i in range(19, 27)]

# Subtract current_time from this value to get rows ordered last to first
MAX_VALUE = 9999999999

# Read RFID every N seconds
RFID_READ_INTERVAL = 3

# Load args
project_id = os.environ["PROJECT_ID"]
instance_id = "data-dash"
table_id = "races"
table_id_meta = "metadata"

# Bigtable objects
client = bigtable.Client(project=project_id)
instance = client.instance(instance_id)
table = instance.table(table_id)
meta_table = instance.table(table_id_meta)

try:
    # Initialize Pi connections to read as BCM
    GPIO.setmode(GPIO.BCM)

    # Initialize sensors
    sensors = [BeamBreakSensor(i, pin, table, meta_table)
               for i, pin in enumerate(PINS, start=1)]

    # Initialize RFID sensor
    reader = SimpleMFRC522()

    # SideController controls if this Pi should 
    side_controller = SideController(meta_table)

    # Column mappings of side_controller
    car_side_map = {
        side_controller.LEFT_CONST: "car1",
        side_controller.RIGHT_CONST: "car2",
    }

    # Initialize the "side" of the webapp this Pi streams
    side = side_controller.get_side()

    id = None
    rowkey = None
    last_scan = 0
    last_seen = 0

    print(side)
    print(f"STARTING SIDE: {car_side_map[side]}")
    while True:
        _time = time.time()

        # Only accept RFID reads after a certain period
        if _time - last_scan > RFID_READ_INTERVAL:
            id = reader.read_id_no_block()
            last_scan = _time

            id_is_car = id and not side_controller.is_side(id)
            # todo: When does side get reset? – (a: side gets reset in is_side cmd)
            if id_is_car:
                side = side_controller.get_side()
                rowkey = f"track{side+1}#{MAX_VALUE - _time}"
                print(f"starting race for {rowkey}")
                row = table.direct_row(rowkey)
                row.set_cell("cf", "car_id", str(id))
                row.commit()

        # Poll sensors
        if rowkey:
            for sensor in sensors:
                try:
                    sensor.read(rowkey)
                except Exception as e:
                    print(f"Error reading sensor {sensor.id}")
finally:
    GPIO.cleanup()