What is Raspberry Pi?

v.s. Arduino?

Raspberry Pi

Operating System

RPi 一般使用基於 Linux kernel 的作業系統

• Raspbian (based on debian)
• Pidora (Fedora)
• Arch linux ARM
• RISC OS
• ...

For more Information...

Go to RPi downloads page!

Enter the RPi World

What you will need

• a RPi
• a computer with an ethernet slot
• ethernet cable
• Android phone for USB tethering (optional)

Step by Step (Windows)

• download pietty
• setup internet sharing

Step by Step (Mac OSX)

• (ssh is bulit-in)
• setup internet sharing:
  System Preferences > Sharing > Internet Sharing

Step by Step (Linux)

• install openssh
• google "linux internet sharing"
  • Arch Wiki
  • Ubuntu Wiki

  use 192.168.137.0/24 subnet

Log in to RPi

• pietty: use pi for "Log in as:"
• ssh:

  ssh pi@192.168.137.10

• password is raspberry

A Brief Guide to Linux

Directory Structure

Command Line

• lscd
• touchrmmvcpmkdirrmdir
• catlessheadtail
• man

Package Manager

• sudo
• apt-get install

Pipeline

串接前一個 stdout 到下一個 stdin

cat /etc/passwd | awk -F: '{print $1}' | less

Editor

• vim
• emacs
• nano

vimrc

syntax on
filetype indent plugin on
colorscheme torte
set nu ai ar
set ts=4 sw=4 
set mouse=a
set bs=indent,eol,start ww+=<,>,[,]

I/O Ports on RPi

GPIO

Limitation

It's not easy to do real-time control with RPi GPIO!!

Programming with GPIO

Languages

• C/C++
• Python
• node.js
• ... and more

Python

RPi.GPIO

import RPi.GPIO as GPIO
# GPIO.setmode(GPIO.BOARD)
GPIO.setmode(GPIO.BCM)

Input/Output

GPIO.setup(chan_in, GPIO.IN)
# this will return GPIO.LOW (0) or GPIO.HIGH (1)
GPIO.input(chan_in)
GPIO.setup(chan_out, GPIO.OUT)
GPIO.setup(chan_out, GPIO.OUT, initial=GPIO.HIGH)
# this will set the output state (GPIO.LOW or GPIO.HIGH)
GPIO.output(chan_out, state)
# chan_list is a list of channel number
GPIO.output(out_list, state)
# len(chan_list) == len(state_list)
GPIO.output(out_list, state_list)

Cleanup

GPIO.cleanup()

Docs

Applications of RPi

Imagine It!

• Sensor
• Monitor
• Controller
• Server
• Player
• ...

Project

Goal

Integrate an RFID sensor with an R Pi. The sensor can scan any easy card and do something cool.

Learning

• Python
• Networking
• Event loop concept
• Reading docs
• Google-Fu

Structure

• Use python to read card information
• Use nodejs or python to serve websocket server
• Use web app to get the information and do something cool

Hardware

材料

• RPi * 1
• RFID 模組
• 杜邦線(母母) * 7

SPI

SPI

RFID

• Each card has a UID (but may not be unique)
• Small storage in the card
• Needs a key to read/write

Software

Dependencies

• python (built-in)
• SPI-Py
• pi-rc522
• websocket

Setup

git clone https://github.com/lthiery/SPI-Py
git clone https://github.com/NTUgEEk/pi-rc522
sudo pip3 install ./SPI-Py
sudo pip3 install ./pi-rc522

How to use

Nodejs websocket

curl -sL https://deb.nodesource.com/setup_7.x | sudo -E bash -
sudo apt install nodejs

npm install --save websocket

sudo pip3 install websockets

Websocket

• nodejs: websocket docs
• python: websocket docs

Flow

• Read card UID using python
• Broadcast UID using websocket server
  format: 255.255.255.255 (string)

Event Loop Concept

import asyncio

@asyncio.coroutine
def compute(x, y):
    print("Compute %s + %s ..." % (x, y))
    yield from asyncio.sleep(1.0)
    return x + y

@asyncio.coroutine
def print_sum(x, y):
    result = yield from compute(x, y)
    print("%s + %s = %s" % (x, y, result))

loop = asyncio.get_event_loop()
loop.run_until_complete(print_sum(1, 2))
loop.close()

Hints

Nodejs

const spawn = require('child_process').spawn;