# [20190526 - Raspberry Pi](https://hackmd.io/s/SkgLJCCnV)
###### tags: `tcfst`
## Author
- Yuan < e61983@gmail.com >
- Wei < demon0303loki@gmail.com >
- Jia-Hao,Hsu < jhs.8901.3737@gmail.com >
## License
## Using Python connect MySQL
- [Try It][online-python_sql]
### Install python-mysqldb
```shell=
sudo apt install -y python-mysqldb
```
or
```shell=
sudo easy_install pip
sudo pip install pip --upgrade
sudo apt-get build-dep python-mysqldb
sudo pip install MySQL-python
```
### Example
#### Read
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
import MySQLdb
db = MySQLdb.connect(host="localhost",
user="db_user", passwd="db_pass", db="db_name")
cursor = db.cursor()
cursor.execute("SELECT * FROM db_table")
# 取回所有查詢結果
results = cursor.fetchall()
for record in results:
col1 = record[0]
col2 = record[1]
print "%s, %s" % (col1, col2)
db.close()
```
#### Insert
```python=
db = MySQLdb.connect(host="localhost",
user="db_user", passwd="db_pass", db="db_name")
cursor = db.cursor()
sql = 'INSERT INTO tempdat \
values(current_data(), now(), 'garage', 18.1)'
try:
cursor.execute(sql)
db.commit()
except:
db.rollback()
db.close()
```
## Using C language connect MySQL
### Install
```shell=
sudo apt install -y libmysqlclient-dev
```
### Example
```c=
#include <mysql.h>
int main(int argc, char **argv)
{
MYSQL *con = mysql_init(NULL);
if (con == NULL)
{
fprintf(stderr, "%s\n", mysql_error(con));
exit(1);
}
if (mysql_real_connect(con, "localhost", "root", "root_pswd",
NULL, 0, NULL, 0) == NULL)
{
fprintf(stderr, "%s\n", mysql_error(con));
mysql_close(con);
exit(1);
}
if (mysql_query(con, "CREATE DATABASE testdb"))
{
fprintf(stderr, "%s\n", mysql_error(con));
mysql_close(con);
exit(1);
}
mysql_close(con);
exit(0);
}
```
## Using PHP connect MySQL
```php=
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("連線失敗: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}
} else {
echo "無结果";
}
$conn->close();
?>
```
## Session & Cookie
負責紀錄在 web server 上的使用者訊息。Session 機制會在一個用戶完成身分認證後，存下所需的用戶資料，接著產生一組對應的 id，存入 cookie 後傳回用戶端。
### PHP Setting
Setting file : /etc/php/7.0/apache2/php.ini
```shell=
sudo vim /etc/php/7.0/apache2/php.ini
```
### Example
index.html:
```html=
<?php
session_start();
if( isset( $_SESSION['counter'] ) ) {
$_SESSION['counter'] += 1;
}else {
$_SESSION['counter'] = 1;
}
$msg = "You have visited this page ". $_SESSION['counter'];
$msg .= "in this session.";
?>
<html>
<head>
<title>Setting up a PHP session</title>
</head>
<body>
<?php echo ( $msg ); ?>
</body>
</html>
```
### Destroying a PHP Session
```php=
<?php
unset($_SESSION['counter']);
?>
```
or
```php=
<?php
session_destroy();
?>
```
### get & post method on PHP
get:
```php=
<?php
echo $_GET[Email];
?>
```
post:
```php=
<?php
echo $_POST["Email"];
?>
```
### 實作會員登入
#### Reference
- [dreamtails-PHP會員登入機制][dreamtails-PHP會員登入機制]
- [SQL語法教學][SQL語法教學]
### More Information
- [PHP 教學][gitbook-PHP]
## I2C - Device
- [datasheet][Datasheet-24LC02]
### 使用 I2C 工具測試
```shell=
# 印出裝置內的資料
sudo i2cdump -y 0x50
# 將第 18 個 byte 的值改寫為 6
sudo i2cset -y 1 0x50 0x12 6
# 讀取第 18 個 byte
sudo i2cget -y 1 0x50 0x12
```
### 使用 Python 讀寫
Example 1
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
import smbus
import time
i2c = smbus.SMBus(1)
addr = 0x50
reg = 0x00
value = 100
i2c.write_byte_data(addr, reg, value)
time.sleep(0.1)
print i2c.read_byte_data(addr, reg)
```
Example 2:
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
import smbus
import time
addr = 0x50
reg = 0x00
vals=[1,2,3,4,5,6,7,8]
i2c.write_i2c_block_data(addr, reg, vals)
time.sleep(0.1)
print i2c.read_block_data(addr, reg, len(vals))
```
## WebIOPi
### Install
```shell=
wget http://webiopi.googlecode.com/files/WebIOPi-0.6.0.tar.gz
tar xvzf WebIOPi-0.6.0.tar.gz
cd WebIOPi-0.6.0
sudo ./setup.sh
```
### Start WebIOPi
Run as program
```shell=
sudo webiopi -d -c /etc/webiopi/config
```
or
Run as service
```
cd /etc/systemd/system/
sudo wget https://raw.githubusercontent.com/doublebind/raspi/master/webiopi.service
sudo systemctl start webiopi
sudo systemctl enable webiopi
```
### Test
Default url: http://localhost:8000/
Default user is "webiopi" and password is "raspberry"
### Change password
```shell=
sudo webiopi-passwd
```
### Reference
- [Official-WebIOPi][Official-WebIOPi]
## RESTful API
REST (Representational State Transfer) API 充分地使用了 HTTP protocol (GET/POST/PUT/DELETE).
RESTful 的優點如下所列:
- 瀏覽器即可以作為 client 端
- 可以更高效地利用 cache 來達到更快的回應速度
- 界面與資料分離
- 節省伺服器的計算資源
- 可重用! (web/android/ios 都可以用, 無痛轉換!)
可以參考:
- [Instagram][instagram-api]
## Javascript
### Data Types
```javascript=
let length = 16; // Number
let lastName = "Johnson"; // String
let x = {firstName:"John", lastName:"Doe"}; // Object
```
### Function
```javascript=
// Function is called, return value will end up in x
var x = myFunction(4, 3);
// Function returns the product of a and b
function myFunction(a, b) {
return a * b;
}
```
### More Information
- [專為中學生寫的 JavaScript 程式書
][gitbook-專為中學生寫的 JavaScript 程式書
]
### CORS
CORS (Cross-Origin Resource Sharing) 即跨域資源共享。他的原理就是使用自定義的 HTTP 頭部，讓服務器與瀏覽器進行溝通，主要是通過設置響應頭的 `Access-Control-Allow-Origin` 來達到目的的。這樣，XMLHttpRequest 就能跨網域了。
#### Reference
- [MDN Web Developer - cors][mozilla-cors]
## Thunkable
- [Official][Official-thunkable]
- App
- [Android][android-thunkable.live]
- [iOS][ios-thunkable.live]
Demo Video
{%youtube BfFRmCjQXiQ %}
## MQTT
MQTT(Message Queuing Telemetry Transport)是機器對機器（M2M）/“物聯網”連接協議。它被設計為一個非常輕量級的發布/訂閱消息傳輸。
- App
- [Android][android-mymqtt]
- [iOS][ios-mqtt-tool]
### Specification
- [MQTT Specification 3.1.1][MQTT-SPEC]
### Using Javascript
#### Example
- Install MQTT.js
```shell=
npm install mqtt --save
```
```javascript=
var mqtt = require('mqtt')
var client = mqtt.connect('mqtt://test.mosquitto.org')
client.on('connect', function () {
client.subscribe('presence', function (err) {
if (!err) {
client.publish('presence', 'Hello mqtt')
}
})
})
client.on('message', function (topic, message) {
// message is Buffer
console.log(message.toString())
client.end()
})
```
### Using C Language
#### Install
```shell=
sudo apt install libmosquitto-dev
```
#### Document
- [Official Man page][doc-mosquitto]
#### Example
```c=
#include <stdio.h>
#include <mosquitto.h>
void my_message_callback(struct mosquitto *mosq, void *userdata, const struct mosquitto_message *message)
{
if(message->payloadlen){
printf("%s %s\n", message->topic, message->payload);
}else{
printf("%s (null)\n", message->topic);
}
fflush(stdout);
}
void my_connect_callback(struct mosquitto *mosq, void *userdata, int result)
{
int i;
if(!result){
/* Subscribe to broker information topics on successful connect. */
mosquitto_subscribe(mosq, NULL, "$SYS/#", 2);
}else{
fprintf(stderr, "Connect failed\n");
}
}
void my_subscribe_callback(struct mosquitto *mosq, void *userdata, int mid, int qos_count, const int *granted_qos)
{
int i;
printf("Subscribed (mid: %d): %d", mid, granted_qos[0]);
for(i=1; i<qos_count; i++){
printf(", %d", granted_qos[i]);
}
printf("\n");
}
void my_log_callback(struct mosquitto *mosq, void *userdata, int level, const char *str)
{
/* Pring all log messages regardless of level. */
printf("%s\n", str);
}
int main(int argc, char *argv[])
{
int i;
char *host = "localhost";
int port = 1883;
int keepalive = 60;
bool clean_session = true;
struct mosquitto *mosq = NULL;
mosquitto_lib_init();
mosq = mosquitto_new(NULL, clean_session, NULL);
if(!mosq){
fprintf(stderr, "Error: Out of memory.\n");
return 1;
}
mosquitto_log_callback_set(mosq, my_log_callback);
mosquitto_connect_callback_set(mosq, my_connect_callback);
mosquitto_message_callback_set(mosq, my_message_callback);
mosquitto_subscribe_callback_set(mosq, my_subscribe_callback);
if(mosquitto_connect(mosq, host, port, keepalive)){
fprintf(stderr, "Unable to connect.\n");
return 1;
}
mosquitto_loop_forever(mosq, -1, 1);
mosquitto_destroy(mosq);
mosquitto_lib_cleanup();
return 0;
}
```
## Python GUI Develop - Tkinter
### Install
```shell=
sudo apt install python3-tk
```
### Example - HelloWorld
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
import tkinter as tk # Python 3.x Version
#import Tkinter as tk # Python 2.x Version
if __name__ == '__main__':
root = tk.Tk()
# Create a text label
label = tk.Label(root, text="Hello World!")
# Pack it into the window
label.pack(padx=20, pady=20)
root.mainloop()
```
### Example - Button
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
import tkinter as tk
def button_click_handler():
label.configure(text="Hi")
if __name__ == '__main__':
root = tk.Tk() button = Button(root, text="show", command=button_click_handler)
button.pack()
root.mainloop()
```
### Event and Binding
```python=
#!/usr/bin/python
# -*- coding: utf-8 -*-
# Python 2.x
from Tkinter import *
import tkMessageBox
def callback():
if tkMessageBox.askokcancel("Quit", "Do you really wish to quit?"):
root.destroy()
root = Tk()
root.protocol("WM_DELETE_WINDOW", callback)
root.mainloop()
```
#### Reference
- [Event and Binding][effbot-even-and-binding]
### More Information
- [Thinter 教學][tutorials-tkinter]
## 梗區
> 我什麼都沒有改啊~怎麼不會動
> [name=Jia-Hao]
> 程式寫得好就不用註解
> [name=ChroXX]
> 公司配的鍵盤Enter鍵是壞的
> [name=Jia-Hao]
>
>> Pchome 24h
>> <img style="width:20%; height:auto;" src="https://i.imgur.com/y9wB0PQ.jpg" >
>> [name=Yuan]
> ~~原來今天有講了這麼多概念阿~~
> [name=Chun-Wei]
[online-python_sql]:
https://www.tutorialspoint.com/python_mysql_online.php
[SQL語法教學]:
https://www.1keydata.com/tw/sql/sql.html
[dreamtails-PHP會員登入機制]:
http://dreamtails.pixnet.net/blog/post/23583385-%5B%E6%95%99%E5%AD%B8%5Dphp%E6%9C%83%E5%93%A1%E7%99%BB%E5%85%A5%E6%A9%9F%E5%88%B6%EF%BC%8Csession%E7%9A%84%E4%BD%BF%E7%94%A8%EF%BC%8C%E7%B0%A1%E6%98%93%E5%9E%8B
[Datasheet-24LC02]:
https://www.holtek.com/documents/10179/116711/HT24LC02v190.pdf
[Official-WebIOPi]:
http://webiopi.trouch.com/
[instagram-api]:
https://www.instagram.com/developer/
[mozilla-cors]:
https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
[mozilla-javascript-tutorial]:
https://developer.mozilla.org/en-US/docs/Learn/JavaScript/First_steps
[Official-thunkable]:
http://app.thunkable.com/login/
[android-thunkable.live]:
https://play.google.com/store/apps/details?id=com.thunkable.live
[ios-thunkable.live]:
https://itunes.apple.com/tw/app/thunkable-live/id1223262700?mt=8
[MQTT-SPEC]:
http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/mqtt-v3.1.1.html
[android-mymqtt]:
https://play.google.com/store/apps/details?id=at.tripwire.mqtt.client
[ios-mqtt-tool]:
https://itunes.apple.com/us/app/mqttool/id1085976398?mt=8
[doc-mosquitto]:
https://mosquitto.org/man/libmosquitto-3.html
[effbot-even-and-binding]:
https://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
[gitbook-專為中學生寫的 JavaScript 程式書
]:
https://ccckmit.gitbooks.io/javascript/content/
[gitbook-PHP]:
https://wizardforcel.gitbooks.io/w3school-php/content/
[tutorials-tkinter]:
https://morvanzhou.github.io/tutorials/python-basic/tkinter/
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