{"id":2139,"date":"2014-05-10T11:02:37","date_gmt":"2014-05-10T07:02:37","guid":{"rendered":"http:\/\/nayarweb.com\/blog\/?p=2139"},"modified":"2014-05-10T11:08:57","modified_gmt":"2014-05-10T07:08:57","slug":"control-raspberry-pis-gpio-with-rest-qt-webiopi","status":"publish","type":"post","link":"https:\/\/nayarweb.com\/blog\/2014\/control-raspberry-pis-gpio-with-rest-qt-webiopi\/","title":{"rendered":"Control Raspberry Pi’s GPIO with REST (Qt, WebIOPi)"},"content":{"rendered":"

Abstract<\/h3>\n

To control the GPIO pins of my raspberry pi<\/em>, I am using WebIOPi framework. You can thus have a web page to remotely control the GPIO from a laptop, mobile phone or anything web capable on ‘http:\/\/192.168.1.x:8000’ where x is the Raspberry Pi on your LAN. You get an interface like this:<\/p>\n

\"snapshot10\"<\/a><\/center>But if you want to create a real application to control the GPIO, you gotta need some API.<\/p>\n

WebIOPi REST API learnt from bash<\/h3>\n

WebIOPi provides a REST API. Here’s the API reference: https:\/\/code.google.com\/p\/webiopi\/wiki\/RESTAPI
\nI’m assuming you have already installed WebIOPi on your Raspberry Pi and the daemon<\/em> is running.<\/p>\n

1.Install curl<\/em> on my laptop. <\/strong>
\n$ sudo apt-get install curl<\/code><\/p>\n

2. Testing a few commands to see if work. <\/strong>(-u username:password)
\n2.1 Making GPIO 4 as OUT<\/p>\n

HTTP GET \/GPIO\/(gpioNumber)\/function
\nReturns “in” or “out”<\/p><\/blockquote>\n

$ curl -v -X POST -u webiopi:raspberry http:\/\/192.168.1.x:8000\/GPIO\/4\/function\/out<\/code><\/p>\n

The web interface displays the change automatically.<\/p>\n

\"snapshot11\"<\/a><\/center>2.2 Outputting voltage on GPIO 4<\/p>\n

HTTP POST \/GPIO\/(gpioNumber)\/value\/(0 or 1)
\nReturns new value : 0 or 1<\/p><\/blockquote>\n

$ curl -v -X POST -u webiopi:raspberry http:\/\/192.168.1.x:8000\/GPIO\/4\/value\/1<\/code><\/p>\n

\"snapshot12\"<\/a><\/center>However, including the above commands in your custom application as a system call is not so desirable because it needs curl to be installed on the target machine and has to be Linux\/UNIX type.To make cross-platform apps which run on Linux, Windows and Android, I use Qt Framework.<\/p>\n

Qt<\/h3>\n

To create the above call in Qt C++, it is done like this:
\n
\n#include<\/span><QDebug><\/span><\/code><\/p>\n

#include<\/span><QNetworkAccessManager><\/span><\/pre>\n
#include<\/span><QUrl><\/span><\/pre>\n
#include<\/span><QNetworkRequest><\/span><\/pre>\n
#include<\/span><QNetworkReply><\/span><\/pre>\n
 int main(int argc, char *argv[])
\n{
\n   int no = 4; \/\/ GPIO number
\n   int value = 1; \/\/ 1 or 0 for On and Off
\n\u00a0 \u00a0QNetworkAccessManager<\/span>*<\/span>manager<\/span>=<\/span>new<\/span>QNetworkAccessManager<\/span>(<\/span>this<\/span>);<\/span><\/code><\/p>\n
   QUrl <\/span>url<\/span>(<\/span>\"http:\/\/192.168.1.6:8000\/GPIO\/\"<\/span>+<\/span>QString<\/span>::<\/span>number<\/span>(<\/span>no<\/span>)\r\n<\/span>+<\/span>\"\/value\/\"<\/span>+<\/span>QString<\/span>::<\/span>number<\/span>(<\/span>value<\/span>));<\/span><\/pre>\n
   url<\/span>.<\/span>setUserName<\/span>(<\/span>\"webiopi\"<\/span>);<\/span><\/pre>\n
   url<\/span>.<\/span>setPassword<\/span>(<\/span>\"raspberry\"<\/span>);<\/span><\/pre>\n
   QNetworkReply <\/span>*<\/span>reply <\/span>= <\/span>manager<\/span>-><\/span>post<\/span>(<\/span>QNetworkRequest<\/span>(<\/span>url<\/span>),<\/span>\"\"<\/span>);<\/span><\/pre>\n
   qDebug<\/span>() <\/span><< <\/span>reply<\/span>-><\/span>readAll<\/span>();\r\n<\/span>}\r\n\r\nYou just need to change the URL each time for different functions ;)<\/pre>\n
Next, i’m gonna create a UI in QML to control the GPIO so as to be able to be used to make a remote controlled car. Stay tuned \ud83d\ude42<\/p>\n","protected":false},"excerpt":{"rendered":"
Abstract To control the GPIO pins of my raspberry pi, I am using WebIOPi framework. You can thus have a web page to remotely control the GPIO from a laptop, mobile phone or anything web capable on ‘http:\/\/192.168.1.x:8000’ where x is the Raspberry Pi on your LAN. You get an interface like this: But if … Continue reading Control Raspberry Pi’s GPIO with REST (Qt, WebIOPi)<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[61,186,167,109,189],"class_list":["post-2139","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-linux","tag-qt","tag-raspberry-pi","tag-ubuntu","tag-webiopi"],"_links":{"self":[{"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/posts\/2139","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/comments?post=2139"}],"version-history":[{"count":15,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/posts\/2139\/revisions"}],"predecessor-version":[{"id":2157,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/posts\/2139\/revisions\/2157"}],"wp:attachment":[{"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/media?parent=2139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/categories?post=2139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nayarweb.com\/blog\/wp-json\/wp\/v2\/tags?post=2139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}