Flask dashboard to control BLE peripheral based RPI

Elev-air-Hardware

Features

• WiFi SoftAP portal service to serve dashboard frontend without internet connection
• Acquisition data from peripheral sensors/actuators as fit to logic
• BLE peripheral role

Assembleing components

First lets plug Grove Base Hat to Pi Zero W. And then, plug modules as follows.

1. Grove MQ2 Gas sensor - A0 of base hat
2. Grove RTC module - I2C slot of base hat
3. Grove Temp/Humi module - D5 of base hat
4. Grove 2 SPTD relay module - D16 of base hat

Configuration

• Installation of Raspberry Pi OS

  1. Flash latest [Raspberry Pi OS] to sd card

  There are several tools to flash sd card with raspberry pi system image such as Win32 Disk Imager etc.

  2. Enable ssh by generating empty file (File name: ssh) in root of SD card

Setting up WiFi hotspot

In ssh terminal, install packages

sudo apt-get update
sudo apt-get upgrade
sudo apt install hostapd -y
sudo systemctl unmask hostapd
sudo systemctl enable hostapd
sudo apt install dnsmasq -y
sudo DEBIAN_FRONTEND=noninteractive apt install -y netfilter-persistent iptables-persistent

Assign a Static IP Address

To start, run the following command in the Terminal:

sudo nano /etc/dhcpcd.conf

It will open the configuration file for dhcpcd. Scroll to the bottom of this file and add the following lines:

interface wlan0
static ip_address=192.168.4.1/24
nohook wpa_supplicant

Save your changes by pressing Ctrl + O followed by Ctrl + x.

Configure Your DHCP and DNS Services

The dnsmasq package provides a default configuration file, but we don’t need all the options included in this file.

To make things easier, rename dnsmasq’s default configuration file and create a replacement file that’s completely empty. Then open this new “dnsmasq.conf” file in the Nano text editor and add only the configuration options that we actually need.

To start, run the following Terminal commands:

sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
sudo nano /etc/dnsmasq.conf

Add the following configuration options:

interface=wlan0
dhcp-range=192.168.4.2,192.168.4.20,255.255.255.0,24h
domain=wlan
address=/gw.wlan/192.168.4.1

Save your changes by pressing Ctrl + O followed by Ctrl + X.

Create a Network Name and Password

Configure your wireless access point by editing the hostapd configuration file.

To open this file for editing, run the following command:

sudo nano /etc/hostapd/hostapd.conf

Add some information about your wireless access point, including giving it a name and securing it with a password. To help protect your access point, your password should be eight characters or more and feature a mix of letters, numbers and symbols.

This tutorial creates an access point called "PiSoftAP" with the password "password2020" – make sure you use something more secure for your own network!

interface=wlan0
ssid=PiSoftAP
hw_mode=g
channel=7
macaddr_acl=0
auth_algs=1
ignore_broadcast_ssid=0
wpa=2
wpa_passphrase=password2020
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP

Save your changes by pressing Ctrl + O followed by Ctrl + X.

Install additional packages

In ssh terminal, execute following commands.

sudo pip3 install Adafruit_DHT
sudo pip3 install grove
curl -sL https://github.com/Seeed-Studio/grove.py/raw/master/install.sh | sudo bash -s -

Setup RTC service for Grove RTC module

• Setup additional packages

  sudo apt-get install python-smbus i2c-tools
  

• Setting up the Raspberry Pi RTC Time

  With I2C successfully setup and verified that we could see our RTC circuit then we can begin the process of configuring the Raspberry Pi to use our RTC Chip for its time.

  1. To do this, we will first have to modify the Raspberry Pi’s boot configuration file so that the correct Kernel driver for our RTC circuit will be successfully loaded in.

  Run the following command on your Raspberry PI to begin editing the /boot/config.txt file.

  sudo nano /boot/config.txt
  

  2. Within this file, you will want to add one of the following lines to the bottom of the file, make sure you use the correct one for the RTC Chip you are using. In our case, we are using a DS1307.

  dtoverlay=i2c-rtc,ds3231
  

  Once you have added the correct line for your device to the bottom of the file you can save and quit out of it by pressing Ctrl + X, then Y and then Enter.

  3. With that change made we need to restart the Raspberry Pi, so it loads in the latest configuration changes.

  Run the following command on your Raspberry Pi to restart it.

  sudo reboot
  

  4. Once your Raspberry Pi has finished restarting we can now run the following command, this is so we can make sure that the kernel drivers for the RTC Chip are loaded in.

  sudo i2cdetect -y 1
  

  You should see a wall of text appear, if UU appears instead of 68 then we have successfully loaded in the Kernel driver for our RTC circuit.

  5. Now that we have successfully got the kernel driver activated for the RTC Chip and we know it’s communicating with the Raspberry Pi, we need to remove the fake hwclock package. This package acts as a placeholder for the real hardware clock when you don’t have one.

  Type the following two commands into the terminal on your Raspberry Pi to remove the fake-hwclock package. We also remove hwclock from any startup scripts as we will no longer need this.

  sudo apt-get -y remove fake-hwclock
  sudo update-rc.d -f fake-hwclock remove
  sudo systemctl disable fake-hwclock
  

  6. Now that we have disabled the fake-hwclock package we can proceed with getting the original hardware clock script that is included in Raspbian up and running again by commenting out a section of code.

  Run the following command to begin editing the original RTC script.

  sudo nano /lib/udev/hwclock-set
  

  7. Find and comment out the following three lines by placing # in front of it as we have done below.

  Find

  if [ -e /run/systemd/system ] ; then
      exit 0
  fi
  

  Replace With

  #if [ -e /run/systemd/system ] ; then
  
  # exit 0
  
  #fi
  

  Once you have made the change, save the file by pressing Ctrl + X then Y then Enter.

• Set TimeZone

  Using raspi-config in terminal,

  4 Localisation Options / I2 Change Time Zone / US / [Choose your Zone]

• Syncing time from the Pi to the RTC module

  Now that we have our RTC module all hooked up and Raspbian and the Raspberry Pi configured correctly we need to synchronize the time with our RTC Module. The reason for this is that the time provided by a new RTC module will be incorrect.

  1. You can read the time directly from the RTC module by running the following command if you try it now you will notice it is currently way off our current real-time.

  sudo hwclock -D -r
  

  2. Now before we go ahead and sync the correct time from our Raspberry Pi to our RTC module, we need to run the following command to make sure the time on the Raspberry Pi is in fact correct. If the time is not right, make sure that you are connected to a Wi-Fi or Ethernet connection.

  date
  

  3. If the time displayed by the date command is correct, we can go ahead and run the following command on your Raspberry Pi. This command will write the time from the Raspberry Pi to the RTC Module.

  sudo hwclock -w
  

  4. Now if you read the time directly from the RTC module again, you will notice that it has been changed to the same time as what your Raspberry Pi was set at. You should never have to rerun the previous command if you keep a battery in your RTC module.

  sudo hwclock -r
  

• Setup syncing date time of Pi from RTC when bootup

  In terminal, execute

  sudo nano /etc/rc.local
  

  and add the following lines to the file:

  sudo hwclock -s
  date
  

  To save the file, press Ctrl+X, Y then return.

Setup systemd service for auto start

• Copy elevator_ble directory to /home/pi/ of Pi via SFTP.

• Create new service in ssh terminal,

  sudo nano /etc/systemd/system/elevatorair.service
  

  Copy following lines:

  [Unit]
  Description=Elevator Air Service for RPI Zero W
  
  [Service]
  TimeoutStartSec=0
  Type = simple
  Restart=always
  RestartSec=15s
  WorkingDirectory=/home/pi/elevator_ble
  ExecStart=/bin/bash start.sh
  
  [Install]
  WantedBy=multi-user.target
  

  To save the file, press Ctrl+X, Y then return.

  cd elevator_ble
  sudo chmod +x start.sh
  sudo systemctl enable elevatorair.service
  sudo systemctl start elevatorair.service
  sudo reboot
  

Finding Pi via WiFi and connecting to admin web

Find WiFi hotspot within your mobile or WiFi builtin machine.

Hotspot ssid: PiSoftAP, password: password2020.

We could change ssid and password easily within section Create a Network Name and Password.

After connected to it, you could browse http://192.168.4.1

BLE peripherals functionalties

• Service UUID: 0d7e0001-3e26-454e-9669-1a8b67b52161"

Charateristic UUID	Descriptions	Access level
0d7e0002-b5a3-f393-e0a9-e50e24dcca9e	Peripheral sensors	notify
0d7e0003-b5a3-f393-e0a9-e50e24dcca9e	Configuration	read/write
0d7e0004-b5a3-f393-e0a9-e50e24dcca9e	Forcing relay	write
0d7e0005-b5a3-f393-e0a9-e50e24dcca9e	Edit schedule	read/write
0d7e0006-b5a3-f393-e0a9-e50e24dcca9e	Adjust system time	notify/write