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Forum Index : Microcontroller and PC projects : Small VGA monitor

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TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6098
Posted: 11:53am 07 Nov 2012
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While looking for a suitable small VGA monitor for a project I was tempted by this 7 inch one.



Having the controller separate suits my purpose and I decided to go for the one with touch screen in the hope that I can get it working. I haven't found any details on the touch screen yet but I am forever hopeful.

I will have a month or so to wait for the display to arrive so there is time for more research.

Search EBay for:
VGA+2AV+Remote control Reversing driver board+7inch AT070TN92 800×480 with touch

Jim
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jdh2550
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Joined: 16/07/2012
Location: United States
Posts: 62
Posted: 12:52pm 07 Nov 2012
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Cool find Jim - thanks. The used Liliputt I got from ebay isn't working very well - and I like the "minimalist nature" of the one you found (as well as the price)

UPDATE: If you just search on "HCR-N1" you'll also turn up some other options. This appears to be the name of the VGA input to TFT panel controller board. I think the TFT 60 pin connector for bare TFT panels is standard. If so you could source the panel and the controller separately for even more flexibility (plus possibly scavenge an LCD from an otherwise dead source?)Edited by jdh2550 2012-11-08
 
jdh2550
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Posted: 04:41pm 07 Nov 2012
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Check out this one:
http://www.ebay.com/itm/VGA-AV-signal-Driver-Borad-7inch-800 -600-resolution-4-3-A070SN02-tft-lcd-display-/170877360368?p t=LH_DefaultDomain_0&hash=item27c91598f0

It's a 4:3 aspect ratio 7" display (rather than the "widescreen" format you posted above). 4:3 will match the aspect ratio of the VGA output so you won't get "stretched" characters.

That link also has a list of other sizes down the left hand side of the page.
 
TassyJim

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Posted: 04:58pm 07 Nov 2012
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The 4:3 would certainly be better but I couldn't see any with touch screen in 4:3

I am guessing that the one I have on order has a 4 wire resistive touch panel.
If that IS the case, I will have a number of options for interfacing.

I can live with the widescreen thanks to the ability to do user defined fonts.

Jim
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Zougie
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Joined: 04/10/2012
Location: Australia
Posts: 18
Posted: 06:38pm 07 Nov 2012
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I just bought two of these off Ebay for around $72 US each:




I haven't received them as yet, but I also liked the 4:3 aspect ratio and 800x600 resolution.

I'll let you know how good they are once I receive them....a couple of weeks.

I too was was quite excited about the LCD modules, but was concerned with mounting strategies and the fact that they're weren't that much cheaper than a complete housed unit. Resolution of these modules looks to be decent though.

Cheers,
George
 
jman

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Joined: 12/06/2011
Location: New Zealand
Posts: 711
Posted: 08:46pm 07 Nov 2012
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Hi

I have one of these mounted in my Pathfinder



http://www.ebay.com/itm/271050767296?ssPageName=STRK:MEWAX:I T&_trksid=p3984.m1438.l2649

I have it mounted into a double Din housing
Works really well I can post some pics if anybody is interested

John
 
jdh2550
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Posted: 06:15am 08 Nov 2012
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  jman said  

I have it mounted into a double Din housing
Works really well I can post some pics if anybody is interested



I'd be interested - one of my projects is to rip out the cassette (yes, remember them?) radio and CD from my Prius and replace it with a home made infotainment device. I plan on hacking into the AVLan bus for control purposes.
 
jman

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Posted: 09:47am 11 Nov 2012
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Hi

Picture of the above monitor installed in my Pathfinder





John
 
jdh2550
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Posted: 11:20am 14 Nov 2012
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John - very nice install. Where did you get the bezel from? Is the USB on the front panel for a USB host connection? What software are you running?

Thanks.
 
jman

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Posted: 11:53am 14 Nov 2012
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Thanks for the kind comments

I got the bezel from here bybyte

The usb is host so I can plugin my iPhone or flash drive in
The Operating system is Windows 7 with Centrafuse as the frontend
Centrafuse makes for a real cool touch friendly system.
Centrafuse
It is also connected the the cars OBDII port so i can see live data from the ECU

The PC itself is mounted under the back set and uses a DC-DC PSU
Lots of hours of setup time
I have also interfaced the steering wheel controls via A/D to USB HID

Regards

John
 
jdh2550
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Posts: 62
Posted: 12:05pm 14 Nov 2012
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  jman said  
I have also interfaced the steering wheel controls via A/D to USB HID

Can you explain this part a bit more? I'm still gathering options for how to upgrade my Prius - I'm thinking of an Android tablet. But may do an LCD hooked to an SBC running Android (rPI? or Olimex A13?). A big part of the puzzle is the best way to interface to the car. If I go tablet then I'll use ADK (an SBC acting as host talking to the tablet) - this will work but it seems like "one processor too many".

Thanks!
 
TassyJim

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Location: Australia
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Posted: 10:55pm 15 Nov 2012
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My new toy arrived today.


The UBW32 is on the left. I really must get one of Mick's boards for the final installation!

The display works well with the Maximite and I have a rough working touch program.
Only two extra resistors were needed for a low parts count.
I have to do a bit more fine tuning with the timing delays but I am pleased with a first attempt.

See the XPT2046 or ADS7843 data sheets for a good description of how the resistive touch screen works.



How the interrupt works:

TouchIntEnable is set high
Y2 is set low

When the touch contact is made the low resistances of the X and Y resistors pulls TouchInt low.
This triggers the interrupt.
TouchIntEnable is then turned off to prevent it from interfering with the readings.

X1 is driven High and X2 low and the mid point voltage read through Y1. The Y resistance has no effect on the reading due to the high input impedence.

Y1 is then driven high and Y2 low and the Y positoin is read through X1.

The delays are needed because of the high capacitance of the touchscreen and we need settling time.

***EDIT: In my real circuit, I have the Interrupt connected to the Y resistor and grounded X2. The theory is the same and it doesn't matter which way it's done.

' touch display demo
' by TassyJim
' 16 Nov 2012
' see the XPT2046 or ADS7843 data sheets for a description
' of how the resistive touch screen works
cls
TouchY1=37 ' 4 analogue input pins for the resistors
TouchY2=35
TouchX1=38
TouchX2=36
TouchIntEnable=34 ' any digital output pin
TouchInt=28 ' digital interupt pin

gosub _touchEnable

_mainLoop:
'do stuff while waiting for a touch
if t=1 then
font 1, 4
print @(100, 40)"X ";Xhit;" ";@(100, 90)"Y ";Yhit;" "
pause 100
gosub _touchEnable
endif
goto _mainLoop

_touchEnable:
setpin TouchY1, 1
setpin TouchY2, 1
setpin TouchX1, 1
setpin TouchX2, 8
Pin(TouchX2)=0
setpin TouchIntEnable, 8
pin(TouchIntEnable)=1
pause 100
setpin TouchInt, 7, _Touched
t=0
return

_Touched:
pause 5 ' debounce time
if pin(TouchInt)=0 then ' touch still there
setpin TouchInt, 0 ' disable the interupt
setpin TouchIntEnable,0 ' disable the interupt resistor
setpin TouchX1, 8 '
Pin(TouchX1)=1 ' X1 is now high and X2 low
pause 5
Xvolt=pin(TouchY1) ' read the X position using Y1
setpin TouchX1, 1
setpin TouchX2, 1 ' set the X as input
setpin TouchY1, 8 ' and the Y as potential divider
setpin TouchY2, 8
Pin(TouchY1)=1
Pin(TouchY2)=0
pause 5
Yvolt=pin(TouchX1) ' read the Y position using X1
Xhit=int(mm.hres*Xvolt/3.3) ' you can scale to any value here
Yhit=int(mm.vres*Yvolt/3.3)
if Xhit >470 or Yhit < 5 then 'reading is suspect
Xhit=0 ' so set the results to zero
Yhit=0
endif
t=1 ' flag to indicate a touch decoded
endif
ireturn


The next job is to get some working menus
(and work out where in the caravan it is going to live)

Jim
Edited by TassyJim 2012-11-17
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