jemenake
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Re: Using an iPad/iPhone/Something as a display?

Tue Apr 03, 2012 7:49 pm

The size and power requirements of the RPi make it idea for use in a car, or for making a little battery-powered unit that I could put in a Rubbermaid container and place somewhere for interesting purposes.

Interfacing with it in the field, for the most part, doesn't seem too tough. USB keyboards and mice are easily portable. Displays, however, are a problem. The cheapest portable HDMI-capable displays I've seen are the Lilliput ones, for a little under $200 (and that's without figuring in any costs of the batteries to power the display in the field).

However, there's an app for the iPad called "Air Display", which allows you to use your iPad as a second monitor for Mac's and PC's. They don't have plans for a Linux driver, but someone else makes an iPad/iPhone app which is an X server.

So, it appears that the promised-land is tantalizingly close. It looks like there might actually be a way to bring a battery-powered RPi out... miles from a power plug, whip out an iPad/iPhone/OtherSomethingWeAlreadyOwnWithADisplay and a keyboard, and boot it and be able to interact with it.

Has anybody made any plans (or headway) for doing something like this?

Harrkev
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Re: Using an iPad/iPhone/Something as a display?

Tue Apr 03, 2012 8:08 pm

VNC is available on Android (should be on iPad too, unless Apple still has a hissy-fit over anything open-source on their store).  It should be no problem to get VNC running on a Pi, since (AFAIK) there is a completely open-source server.

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Jim Manley
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 3:59 am

Yes, you can use any of a number of VNC apps on the iPad (or iPhone/iPod Touch, if you"re a real glutton for bleary-eyed punishment) to view the R-Pi desktop, you can also SSH (Secure SHell) in for command-line access, SFTP (Secure File Transfer Protocol) to transfer files, and pretty much everything else you can do from any laptop/desktop into a Linux system over a network. Just search for each of these terms in the App Store (along with "free" if you don"t need every whiz-bang feature) and you will find dozens of apps. Different people like various features, so try them all and ditch the ones you don"t like (the star ratings and comments are a good general guide as to which are the most stable and have the most popular features). Some free apps are lite versions of commercial apps and, if you find some you really like and need the advanced features in a paid version, it"s a good way to test drive the various offerings.
The best things in life aren't things ... but, a Pi comes pretty darned close! :D
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!

zfh10
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 8:59 am

Interesting.

I want to (ideally) figure out a way of hooking up a replacement iphone screen, although I'm not sure it is currently possible.  Looks promising, but I don't think anyone has done it yet.

If I can't find a little screen, is it possible to instead use this remote-view app to use the RasPi mainly as a juke box?  Connected would be speakers, usb hard drive, usb wifi dongle.  But no monitor.  Could I somehow use my android tablet or another pc to remotely control the Pi?

davesedar
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 11:09 am

I was hoping to connect the AV-OUT port of the Pi to the AV-IN port of a low-cost sat-nav (eg http://www.ebay.co.uk/itm/2609.....5998wt_952 )

as a monitor in the car.

Any idea if it would work?

ceteras
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 1:28 pm

@davesedar, I don't know about that one, but for example, I have an old Philips Carin gps nav system, and its display works with separate video input. That would work, but at a very low resolution, good for a SD video player maybe.


jemenake
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 2:00 pm

davesedar said:


I was hoping to connect the AV-OUT port of the Pi to the AV-IN port of a low-cost sat-nav (eg http://www.ebay.co.uk/itm/2609.....5998wt_952 )

as a monitor in the car.

Any idea if it would work?


I thought of that, too. My Sat-Nav has a composite-in for hooking up a backup camera. However, that idea falls flat for two reasons: 1) I've already got a backup camera hooked to it, and 2) The resolution would be terrible.

I hadn't thought of using VNC or ssh, but now... it's starting to make sense.

When I started this thread, the notion was to use a dedicated keyboard (and mouse, if needed) and all I needed was an external display. VNC would work for this, but then you have the problem of establishing a LAN connection between the iPad and the RPi.

Because the iPad doesn't have a wired LAN socket, there are only two ways (that I can think of) to get them talking to each other: 1) Plug a wi-fi dongle into the RPi and then, somehow, turn it into an access point, or 2) Rig up a battery-powered wireless router (like a little FON router or even a bigger, 4-port one) and then plug the RPi into one of its wired ports). I'd be interested to know how easy it would be, using one of the standard RPi distros, to turn it into an access point.

But the mention of SSH and VNC got me thinking along other lines. I could just use my laptop. I already use it to SSH into lots of other hosts, it has a wired ethernet port, it brings its own keyboard and pointer, and all I have to do is either run a dhcpd on the RPi to give my laptop an IP, or I can just hard the laptop's IP.

I'm still interested in hearing about what everyone else is going to do, but I think I've decided on my solution: laptop with wired ethernet, and using SSH (and, optionally, an X server) to control the RPi.

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Jim Manley
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 9:43 pm

jemenake,

Yes, you can use anything that can establish a wired Ethernet or WiFi connection to control your R-Pi. You"ll need to hook up a monitor and keyboard (plus mouse/trackpad for a GUI) to the R-Pi in order to configure the VNC, SSH, SFTP, HTTP/SHTTP, etc., services to come up on boot, plus a password-protected user account (do _not_ just use root, use sudo from the user account) but, once that"s done, you won"t need the other I/O devices. To get WiFi, just plug in a ~$10 USB WiFi dongle (which may need to be configured for boot, e.g., access point address, use DHCP, etc.) and any device with WiFi will be able to access the R-Pi via the user account you created. Easy-peasy!
The best things in life aren't things ... but, a Pi comes pretty darned close! :D
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!

hamjudo
Posts: 59
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Re: Using an iPad/iPhone/Something as a display?

Wed Apr 04, 2012 9:56 pm

I am going to try a really cheap used Android phone (no service) and a Bluetooth dongle for a low bandwidth remote control and status display for my robot. Bluetooth won't work all applications, but it is really inexpensive. This should give me something that acts like a serial port. There would be a Python script on the RPi running in the robot, and a Python script in the rooted Android phone.

This wouldn't be a generic solution, just something to display a few values, like battery voltage, and to provide an E-stop function for the robot when it is autonomous, and a driver station when it isn't.

jemenake
Posts: 3
Joined: Tue Apr 03, 2012 6:18 pm

Re: Using an iPad/iPhone/Something as a display?

Thu Apr 05, 2012 1:54 am

hamjudo said:


I am going to try a really cheap used Android phone (no service) and a Bluetooth dongle for a low bandwidth remote control and status display for my robot. Bluetooth won't work all applications, but it is really inexpensive. This should give me something that acts like a serial port.


Nice idea! Yeah... I don't want to have to delve into how to get IP networking going over bluetooth, but it should be pretty easy to set up a ttyS0 serial port. From there, you can probably use inittab to run mgetty to give you a login prompt over serial.

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