"Honwaka Notification Lamp" on Raspberry Pi Part 1

Help monitor with Raspberry Pi

Create a device that gently notifies you of notifications from the system with Raspberry Pi. The goal is like this.

• Get changes to be notified from Cloud
• If you find a change, let us know with a lamp and chime
• Separate the color, blinking speed, and chime type according to the notification content.

Get Raspberry Pi

I bought the RaspberryPi from Amazon.

The attached special case has an opening in the GPIO socket part and is suitable for connecting to the base outside the case.

System configuration

The configuration of the notification lamp is as follows.

In this article, I will write about the hardware part of "Color LED" and the "Led Driver" part that operates it.

hardware

Make the hardware of the "notification lamp". The mechanism of operating the LED from Raspberry Pi is almost the same as ["L Chika" written by many people](http://qiita.com/search?utf8= ✓ & sort = rel & q = L Chika + raspberry Pi & sort = rel) is.

There are various types of color LEDs, and there are various methods for controlling brightness and color, but here, we will design based on the following.

• Power LED drive with transistor array The GPIO output of the Raspberry Pi is amplified by a transistor (array) so that sufficient current can flow through the Power LED.

• Color control by software PWM (Puls Width Moduration) In order to be able to freely control the brightness of the three color LEDs with software, we will make a circuit that can independently turn on / off each RGB color by operating GPIO.

Wiring diagram

You can change the GPIO port to use. In that case, change the definition of the program described later.

Used parts

The parts were purchased at Akizuki Denshi Tsusho (mail order).

Tools and consumables

The following tools and consumables are recommended for production.

Parts placement

The appearance of the produced board is as follows.

On the back of the right end, there is a 40-pin pin socket for connecting to the Raspberry Pi. This pin socket has a long pin, but if you solder it at the tip without cutting it, you can connect it just so that the base rests on the case. In the photo, the gray part in the upper center of the board is the "push switch", but it is not used in this explanation, so please ignore it. The base of the Power LED is aluminum, so be careful not to let the wiring touch the edges. Although not visible in the photo, three 47Ω resistors are located under the LED.

Led Driver The module that controls the color and blinking of the LED is called "Led Driver" here. By configuring the "notification lamp" as a child process of the calling process, it is possible to operate asynchronously with the upper module.

The functionality of the Led Driver is simple. If you specify "Color" and "Blinking cycle (seconds)", the LED will continue to blink as it is. If you change the specification during the blinking process, it will be reflected within 1 second.

The module configuration is as follows.

• Led Class that performs LED blinking
• LedDeamon Class that handles Deamonization and interprocess communication

IPC queues are used to communicate with Deamon. LedDeamon will change to the default Down state display if the lighting mode setting (set_mode) is not executed for 80 seconds. This is a function for detecting down of the upper program.

For details, see the source code below.

I'm new to Python, so I'm looking forward to your warmth!

Test execution method:

python

$ sudo ./led.py

led.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import RPi.GPIO as GPIO
import time


class Led(object):
    # Define your GPIO Ports
    RED_PORT = 13
    GREEN_PORT = 26
    BLUE_PORT = 5

    # Controll resolution Params
    # You don't have to change following 3 Params usually
    FREQUENCY = 200  # PWM Frequency
    RESOLUTION = 50.0  # Brightness control per span
    SPAN = 1.0  # Drive time in second at one call

    # Brightness
    MAX_BRIGHTNESS = 1.0 # Master Brightness parameter 0.1 - 1.0

    # Color Table
    # You can append your own colors
    COLORS = {
        "Red": [1.0, 0.0, 0.0],
        "Pink": [1.0, 0.3, 0.3],
        "Green": [0.0, 1.0, 0.0],
        "LightGreen": [0.2, 1.0, 0.2],
        "Blue": [0.0, 0.0, 1.0],
        "LightBlue": [0.3, 0.3, 1.0],
        "Yellow": [1.0, 1.0, 0.0],
        "Orange": [1.0, 0.3, 0.0],
        "Cyan": [0.0, 1.0, 1.0],
        "Lime": [0.0, 1.0, 0.3],
        "Magenta": [1.0, 0.0, 1.0],
        "Violet": [0.3, 0.0, 1.0],
        "White": [1.0, 1.0, 1.0],
        "Black": [0.0, 0.0, 0.0]
    }
    # Color index for Color Table
    RED = 0
    GREEN = 1
    BLUE = 2

    def color_names(self):
        return Led.COLORS.keys()

    def __init__(self):
        self.phase = 0.0
        self.color = Led.COLORS["Black"]

        GPIO.setmode(GPIO.BCM)

        # set GPIO port as output
        GPIO.setup(Led.RED_PORT, GPIO.OUT)
        GPIO.setup(Led.GREEN_PORT, GPIO.OUT)
        GPIO.setup(Led.BLUE_PORT, GPIO.OUT)

        # set port as software PWM with f Hz
        self.red = GPIO.PWM(Led.RED_PORT, Led.FREQUENCY)
        self.green = GPIO.PWM(Led.GREEN_PORT, Led.FREQUENCY)
        self.blue = GPIO.PWM(Led.BLUE_PORT, Led.FREQUENCY)

        # start software PWM with 0.0%
        self.red.start(0.0)
        self.green.start(0.0)
        self.blue.start(0.0)
        return

    def _set_brightness(self, brightness):
        percent = Led.MAX_BRIGHTNESS * (brightness ** 2) * 100.0
        # set duty cycle
        self.red.ChangeDutyCycle(min(100.0, percent * self.color[Led.RED]))
        self.green.ChangeDutyCycle(min(100.0, percent * self.color[Led.GREEN]))
        self.blue.ChangeDutyCycle(min(100.0, percent * self.color[Led.BLUE]))

    def set(self, color, interval):
        # Color name to RGB value
        self.color = Led.COLORS[color]

        # interval in second
        self.interval = float(interval)

        # control resolution parameter
        if self.interval > 0.0:
            self.pitch = 1.0 / (Led.RESOLUTION * self.interval)

        # Reset phase
        self.phase = 0.0

    def run(self):
        if self.interval == 0.0:
            # No Blink
            self._set_brightness(0.5)
            time.sleep(Led.SPAN)
        else:
            for i in range(int(Led.RESOLUTION * Led.SPAN)):
                self.phase += self.pitch
                if self.phase >= 1.0:
                    self.phase = 0.0
                if self.phase < 0.5:
                    br = self.phase * 2.0
                else:
                    br = 1.0 - ((self.phase - 0.5) * 2.0)
                # keep a little light
                br += 0.0001
                self._set_brightness(br)
                time.sleep(1.0 / Led.RESOLUTION)

    def destroy(self):
        self.red.stop()
        self.green.stop()
        self.blue.stop()
        GPIO.cleanup()

if __name__ == ("__main__"):

    l = Led()
    l.set("Blue", 0.5)
    l.run()
    l.set("Black", 0)
    l.run()
    for interval in [0, 0.5, 1.0]:
        print("- Inrerval = %2.1f" % interval )
        for c in l.color_names():
            if c == "Black":
                continue
            print(c)
            l.set(c, interval)
            for i in range(max(1, int(interval * 2.0))):
                l.run()
    l.destroy()

Test execution method:

python

$ sudo ./led_deamon.py

led_deamon.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-


import time
import multiprocessing
import Queue
from led import Led


class LedDeamon(object):
    DOWN = {"color": "Magenta", "interval": 0}

    def __init__(self):
        self.queue = multiprocessing.Queue()
        self.lighting_mode = None

    def start(self):
        p = multiprocessing.Process(target=self._led_control, args=(self.queue, ))
        # Set deamon flug to kill process when parent process died
        p.daemon = True
        p.start()

    def set_mode(self, lightning_mode):
        self.queue.put(lightning_mode)

    # Child loop
    def _led_control(self, queue):
        count = 0
        lighting_mode = LedDeamon.DOWN
        self.led = Led()
        while True:
            # get mode from queue
            try:
                lighting_mode = self.queue.get(False)
                count = 0
                # print("lighting_mode = %s" % lighting_mode)
            except Queue.Empty:
                count += 1
                # parent seems dead
                if count > 80:
                    lighting_mode = LedDeamon.DOWN
            self._drive(lighting_mode)  # Drive for about 1 sec.

    def _drive(self, lighting_mode):
        if self.lighting_mode != lighting_mode:
            self.lighting_mode = lighting_mode
            self.led.set(lighting_mode["color"], lighting_mode["interval"])
            # print("lighting_mode = %s" % lighting_mode)
        self.led.run()

if __name__ == '__main__':
    mode_map = {
        "DOWN": {"color": "Magenta", "interval": 0},
        "ERR_UNACKED": {"color": "Red", "interval": 0.5},
        "WARN_UNACKED": {"color": "Yellow", "interval": 2},
        "ERR_ACKED": {"color": "Green", "interval": 4},
        "WARN_ACKED": {"color": "Green", "interval": 8},
        "NORMAL": {"color": "Blue", "interval": 8}}

    # Create and start LED Driver
    ld = LedDeamon()
    ld.set_mode(mode_map["NORMAL"])
    ld.start()
    time.sleep(8)
    ld.set_mode(mode_map["ERR_UNACKED"])
    time.sleep(8)
    ld.set_mode(mode_map["WARN_UNACKED"])
    time.sleep(8)
    ld.set_mode(mode_map["ERR_ACKED"])
    time.sleep(8)
    ld.set_mode(mode_map["WARN_ACKED"])
    time.sleep(8)
    ld.set_mode(mode_map["DOWN"])
    time.sleep(8)

Limitations

• Does not consider simultaneous use from multiple processes
• Full software control, so it may flicker a little when the system is overloaded.
• If GPIO is used for other purposes, it needs to be modified.
• Since it is software controlled, it consumes a little CPU. Python process is about 2.5% of 1Core. It seems that it consumes about 1% of the total 4Core.

bonus

This is how it shines when an important problem occurs. When combined with a suitable chime, you can create a sense of urgency. (I don't want to see it too much ...)

The dome-shaped cover that covers the LED is a diversion of the LED light cover that was sold at Daiso. Actually, the hardest part of hardware production was finding this cover. (Lol)

Next schedule

Next time, I will write about the module Detector that controls notifications.