Programming the Raspberry Pi

[Gina]

Thanks Ian   FreeView also works in Linux but not sure what the pros and cons are.

[Gina]

I've ordered a dedicated HDMI monitor with touch screen for the RPi from Amazon UK with Prime delivery tomorrow.  I already have HDMI cables.

Elecrow HDMI Display Monitor 5 Inch HD 800x480 TFT LCD Display for Raspberry Pi 2B B+ Raspberry Pi 3B with Touch Screen

[SilverAstro]

2 hours ago, Gina said:

I've ordered a dedicated HDMI monitor with touch screen for the RPi from Amazon UK

Nice find, thanks ! Never occurred to me to go looking for that sort of thing, not a bad price well in pocket money.

amazing what one learns on fora   I wonder if they do bigger ones, much bigger for my aged eyes ! I 'spect so, so that my domestic staff wont feel the loss of the 40" thing in the corner   It is all looking very retro, hours spent infront of TVs with ZX81 and BeebBs

PS aside - I downloaded NOOBs+Ras, dont know why !, a mad moment,  1hr7min !! , all I need now is a Pi 

[Gina]

I think there's a 7" screen for the RPi but a lot higher price as I recall.  I'll see what I can find.  Amazon do HDMI monitors without touch screens or you can use a small television set - most have HDMI these days.

[Gina]

There's lots about via Google but Amazon seems the cheapest.  You can do your own search, of course   You may find something I've missed.  Cheaper if you're not in a hurry and can wait a few weeks for delivery for China etc.

Here's a bigger one on Amazon :- Makibes@7 Inch Capacitive Touch Screen LCD HDMI 800×480 For Raspberry Pi/BB BLACK/PC/Various Systems

[SilverAstro]

13 minutes ago, Gina said:

 without touch screens or you can use a small television set

Yes TV set was my initial thought, had not thought about dedicated wee things like you found, yes I'll have to do some searching !

had not thought about the "touch" bit, do you think that is going to be an important/desirable thing for functionality of a Pi ?

My main interest in it, such as it was so far, is as a small stand alone controller of various things ( and as a retro toy !! I admit )  I am still havering over going the arduino route but dont much like C any more, flogged my brain cell over it for too long in other rolls, , Python suits my style more !

[Gina]

Not sure how much benefit a touch screen is going to be but I'll find out in due course.  I'm quite happy with C or Python but might get confused if I'm using both, I guess.  I do tend to be more confused these days!!

[SilverAstro]

47 minutes ago, Gina said:

Not sure how much benefit a touch screen is going to be but I'll find out in due course.  I'm quite happy with C or Python but might get confused if I'm using both, I guess.  I do tend to be more confused these days!!

I know what you mean ! I'm wondering if I can remember where my USB kbs & mice were put !!

[Gina]

RPi touch screen has arrived   There's no instructions with it but it evidently plugs into the RPi GPIO socket and has an HDMI adapter to connect the HDMI.  I would assume that the LCD picture is sent via HDMI and the touch screen communicates via the GPIO.

 

[Gina]

Also arrived today was "Raspberry Pi for Dummies" so I'll be doing some reading.

Before I make any changes to the micro SD I shall need to back it up.

[psamathe]

57 minutes ago, Gina said:

RPi touch screen has arrived   There's no instructions with it but it evidently plugs into the RPi GPIO socket and has an HDMI adapter to connect the HDMI.  I would assume that the LCD picture is sent via HDMI and the touch screen communicates via the GPIO

(Not an important point but) Maybe power through the GPIO ? (does HDMI include a power output ?)

Ian

[Gina]

There's a mini USB connector on the screen so that's probably for power.  However, there is 5v available on GPIO so I shall have to investigate further.

[Gina]

Powered up the RPi 3 from my bench PSU USB power port.  Here's the screen display...

[Gina]

Yes, the micro SD card is IN and everything is properly connected.  I'll try the HDMI output on a television next.

[Gina]

In took everything apart and put it back together again, connected the power and switched on.  This time the display sprang into life and displayed a stream of startup lines usual for a Linux start.  However, after a few seconds, the screen gradually got stronger and stronger vertical lines of various colours.  I decided to take a series of photos of this process - which was repeatable - and here it is.

[Stub Mandrel]

What happens if you switch it on with no input?

[Gina]

This is without an input.  Nothing plugged into the USB sockets and only the touch screen module connected to the GPIO and HDMI.  The only other connection is a genuine RPi power cable plugged into a USB power source (USB power socket on bench PSU).

Tried it on a TV via a short HDMI cable (touch screen module removed) and it started up normally and after a little while displayed a graphical interface with a gert big raspberry in the middle.  Later, after several minutes it seems to have gone into screen-saver mode - black with just a coloured square in the top right corner.

I wonder if the load of the touch screen module increases the overall load current from the supply to over the standard 500mA USB current rating.  If so I would have thought anything plugged into the USB ports would also add to the load.  I find it strange that the RPi is designed to run off a single USB connection rather than proper external power like the Arduino.

[Gina]

Been doing some reading and it seems the RPi 3 needs up to 2.5A and not standard USB 500mA - maybe I got a cable for an early RPi model.  Anyway, for while I'm experimenting, I've ordered a genuine RPi power supply.  Also, reading the RPi web site it seems the RPi 3 wants 5.1v rather than 5v.  For astronomy use I shall make up a special power cable and run the RPi from a "buck converter" or other voltage regulator, from my 13.8v observatory power supply.

[psamathe]

15 hours ago, Gina said:

Been doing some reading and it seems the RPi 3 needs up to 2.5A and not standard USB 500mA - maybe I got a cable for an early RPi model.  Anyway, for while I'm experimenting, I've ordered a genuine RPi power supply.  Also, reading the RPi web site it seems the RPi 3 wants 5.1v rather than 5v.  For astronomy use I shall make up a special power cable and run the RPi from a "buck converter" or other voltage regulator, from my 13.8v observatory power supply.

Mine runs fine from various USB power sources (not found one yet that it does not work on).

Re the current - I think how much is needed will depend on how much you are taking out (e.g. through devices connected such as USB devices powered through through RPi). RPi3 has 4 USB ports that provide power so clearly the input will have to be adequate to deliver that power (as well as power the RPi itself).  I'd expect that screen to be taking some of that current as well.

In my own case as I hope in the future (longer term?) to be using auto-guiding through the RPi and my impression is that most cameras sold for auto-guiding are USB powered that with powered auto-guiding USB camera, mount I/F, imaging camera and filter wheel (longer term) so I've avoided as many additional power drains on the RPi.  Most of the time I run it from my astro 12V battery using a 24W car USB power adapter (one that will deliver 2.4 amps to the RPi).

Ian

[Gina]

I took the USB plug off the power cable, stripped back the wires and connected the +5v and Gnd to the +ve and -ve terminals of my bench PSU.  Connected power lead to micro USB socket and HDMI to a TV set and switched on.  RPi 3 booted up and displayed the graphics screen.  No coloured square - which I found out indicated low power.  As it started up and displayed it's load of text etc. I watched the current taken and it went up to about 0.6A then settled back down to around 0.2A.  The USB power output on my bench PSU is rated at 500mA so that was the problem before.

Wireless trackball arrived in the post this morning but the keyboard is coming by courier - hopefully this afternoon.  I was able to use the trackball to go through the menus and look around.  I ran Python 3 but since that came up in text mode I couldn't go any further without a keyboard. 

I then shut down, removed power and plugged the 5" LCD touch screen in and powered up again.  This time the supply current went up to nearly an amp before settling down to just over 200mA.  The screen worked properly   However the text on it is very small and I don't think I shall use it for programming or anything text based.  I have a 19" TV that will provide quite a nice display for the RPi for getting it set up and programmed.

[Gina]

Keyboard has arrived and I have plugged it into the RPi.  Everything connected and running and I'm typing this on the RPi keyboard.  Comms is via Ethernet CAT5E cable to router as I haven't setup WiFi yet.  It all just works

Why anyone should be afraid of Linux I don't know.  Here I have a complete computer system with browser, email, office app, picture editor etc. etc. and all just available from a menu just like Windows - except that this system is way faster   Shortly I'll add up all I've bought to enable this to work.  Let me just add that this is the first time I have had the Raspberry Pi working except for quick tests.  This is a very cheap wired keyboard and not as nice as my regular one but quite adequate.  The screen is a cheap small television set connected via HDMI cable.  Rather smaller than my desktop monitor but again quite adequate.

Connecting to SGL was simply a matter of choosing the browser from the menu and entering "stargazers lounge" in the search.  Then I just entered my name and password in the SGL login and here I am.

But this RPi is not for general computer use - it's for running my imaging sessions.  That is a bit more technical.  Use as a PC is not the slightest technical as long as you know how to plug things in

I'll go from here now as this lot is set up on the living room table and against the light and it's straining my poor old eyes

[kens]

When you come to using it for imaging, you will almost certainly want to add in a powered USB hub to take the load off the Pi. That is assuming you haven't done that already. Its amazing how quickly you use up ports. My 7 port hub has:

1. Power for the Pi
2. EQDIR (or possibly Buetooth dongle for EQDIR-BT - not needed for Pi3)
3. Imaging cam
4. Guide cam
5. Memory stick (ny boot drive and for image storage)
6. Wifi dongle (not needed for Pi3)
7. Reserved for either focusser or gamepad dongle

 

[wimvb]

I just got the INDI server installed on my RPi B with Ubuntu Mate as OS.

Have controlled my AZ EQ6 from this setup using the HITECASTRO eqdir adapter between the RPi and the mount. As indi client I used PixInsight. It works great, but the client isn't fully developed yet. It should also work with Stellarium, but couldn't get it to work

I control the RPi through my home network, running PuTTY on a windows 8 laptop.

In the field it should also work with a mobile phone as a hotspot, but data transfer is very slow with this solution (at least it was when using a phone as hotspot in another application)

For now, the RPi server is on hold as it has been too cloudy for any testing. (Probably an aftereffect of me buying the aforementioned AZ EQ6)

Here's a short write up of my first experiences

http://wimvberlo.blogspot.se/2016/08/first-experience-with-indi-on-raspberry.html

(2 posts in this link)

[Gina]

Thank you both   Interesting

[wimvb]

12 hours ago, kens said:

When you come to using it for imaging, you will almost certainly want to add in a powered USB hub to take the load off the Pi. That is assuming you haven't done that already. Its amazing how quickly you use up ports. My 7 port hub has:

1. Power for the Pi
2. EQDIR (or possibly Buetooth dongle for EQDIR-BT - not needed for Pi3)
3. Imaging cam
4. Guide cam
5. Memory stick (ny boot drive and for image storage)
6. Wifi dongle (not needed for Pi3)
7. Reserved for either focusser or gamepad dongle

 

Do you control this stuff with the RPi (running a server like indi)? Or do you channel the equipment through the RPi to your computer (virtual usb ports)?