SynonZelra
Posts: 8
Joined: Sun Jan 11, 2015 10:07 am

Building a protable pi

Sun Jan 11, 2015 5:21 pm

Greetings everyone.

I'm considering about building a portable pi and I've got two confusions about a screen.

1)I'm told that it you attach a TFT via GPIO, it consumes more power and performace than the HDMI or RCA way because the GPIO driver requires more CPU workload. Pls correct me if this is wrong.

2)I'm also considering about maybe a driving monitor with RCA. i've learned this may work between 6 to 12 voltage.
if i take two 18650 battery parallel, it's like about 7.4v, and take two output line in parallel, connect one to a converter to 5v while the other one direct to the TFT, is this possible?

3)If you have any other solutions on battery, you are more than welcome.

Thanks

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mahjongg
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Re: Building a protable pi

Sun Jan 11, 2015 5:30 pm

SynonZelra wrote:Greetings everyone.

I'm considering about building a portable pi and I've got two confusions about a screen.

1)I'm told that it you attach a TFT via GPIO, it consumes more power and performace than the HDMI or RCA way because the GPIO driver requires more CPU workload. Pls correct me if this is wrong.

2)I'm also considering about maybe a driving monitor with RCA. i've learned this may work between 6 to 12 voltage.
if i take two 18650 battery parallel, it's like about 7.4v, and take two output line in parallel, connect one to a converter to 5v while the other one direct to the TFT, is this possible?

3)If you have any other solutions on battery, you are more than welcome.

Thanks
1) WRONG! You can connect some, carefully selected TFT displays if you write a driver for them , or if they are compatible enough with an existing TFT for which a driver already exist, you can use that driver. But yes, there is a small penalty in performance, but its not really noticable (depending on the quality of the driver).

2) I depends heavily on the panel (with composite video input) you use, many are designed to work with the 12V from a car, but in practice may accept less than that 12V, as the internal 12V to 5V converters can accept less. As said, most internally work on 5V, and you can sometimes bypass the internal 12V to 5V switching power supply, and apply 5V directly.
But they would consume much more energy than a bare TFT panel, as they need a lot of (power using) electronics to convert the analog Composite video back to digital signals for the built in TFT panel.

PiiPatient
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Re: Building a protable pi

Sun Jan 11, 2015 6:19 pm

[quote="SynonZelra"]Greetings everyone.

I'm considering about building a portable pi and I've got two confusions about a screen.
/quote]
I found this on YouTube...>>> http://youtu.be/NhalgdxuOpU?t=1m41s
Certified Glazier/Metal Mechanic, Certified Chef, Hobby Electronics enthusiast. Audiophile

SynonZelra
Posts: 8
Joined: Sun Jan 11, 2015 10:07 am

Re: Building a protable pi

Mon Jan 12, 2015 11:49 am

mahjongg wrote:
SynonZelra wrote:Greetings everyone.

I'm considering about building a portable pi and I've got two confusions about a screen.

1)I'm told that it you attach a TFT via GPIO, it consumes more power and performace than the HDMI or RCA way because the GPIO driver requires more CPU workload. Pls correct me if this is wrong.

2)I'm also considering about maybe a driving monitor with RCA. i've learned this may work between 6 to 12 voltage.
if i take two 18650 battery parallel, it's like about 7.4v, and take two output line in parallel, connect one to a converter to 5v while the other one direct to the TFT, is this possible?

3)If you have any other solutions on battery, you are more than welcome.

Thanks
1) WRONG! You can connect some, carefully selected TFT displays if you write a driver for them , or if they are compatible enough with an existing TFT for which a driver already exist, you can use that driver. But yes, there is a small penalty in performance, but its not really noticable (depending on the quality of the driver).

2) I depends heavily on the panel (with composite video input) you use, many are designed to work with the 12V from a car, but in practice may accept less than that 12V, as the internal 12V to 5V converters can accept less. As said, most internally work on 5V, and you can sometimes bypass the internal 12V to 5V switching power supply, and apply 5V directly.
But they would consume much more energy than a bare TFT panel, as they need a lot of (power using) electronics to convert the analog Composite video back to digital signals for the built in TFT panel.
As per checked some video, i feel that a GPIO TFT seems a little lag in displaying, I don't know why.

I've also seen the fbtft, and maybe that's not so hard to find a tft with listed ICs, but I'm a pure amateur and I'm afraid I can't figure out the pin connection.

Today I have visited the local market, figuring that the car monitor is really cheap (about 10 pound in equivalent), so that's no big deal to get one for testing.

Thanks

PiGraham
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Re: Building a protable pi

Mon Jan 12, 2015 12:03 pm

What size screen do you want? How important is display quality? 2 to 4 inch TFTs on SPI bus GPIO work quite well.
There are many cheap 7" 800 x 480 TFT screens around, many with touch, that have HDMI interface boards. They will give a much better picture than the smaller TFTs.

Composite video will give a poorer quality display than a digital interface (SPI or HDMI) for a give screen resolution.

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kusti8
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Re: Building a protable pi

Mon Jan 12, 2015 1:25 pm

http://blog.parts-people.com/2012/12/20 ... rpi-to-go/
It even includes the files to 3d print the case.
There are 10 types of people: those who understand binary and those who don't.

SynonZelra
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Re: Building a protable pi

Tue Jan 13, 2015 6:44 pm

PiGraham wrote:What size screen do you want? How important is display quality? 2 to 4 inch TFTs on SPI bus GPIO work quite well.
There are many cheap 7" 800 x 480 TFT screens around, many with touch, that have HDMI interface boards. They will give a much better picture than the smaller TFTs.

Composite video will give a poorer quality display than a digital interface (SPI or HDMI) for a give screen resolution.
Hi,

I would like a size between 4 to 5 inch.

As for the quality, it's a little hard to describe. I don't care much about the colour, but maybe a fresh rate is more important. I mean, if you are programming, that's no big deal, but if you play a video, lagging will kill it.

PiGraham
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Location: Waterlooville

Re: Building a protable pi

Tue Jan 13, 2015 8:55 pm

SynonZelra wrote:
PiGraham wrote:What size screen do you want? How important is display quality? 2 to 4 inch TFTs on SPI bus GPIO work quite well.
There are many cheap 7" 800 x 480 TFT screens around, many with touch, that have HDMI interface boards. They will give a much better picture than the smaller TFTs.

Composite video will give a poorer quality display than a digital interface (SPI or HDMI) for a give screen resolution.
Hi,

I would like a size between 4 to 5 inch.

As for the quality, it's a little hard to describe. I don't care much about the colour, but maybe a fresh rate is more important. I mean, if you are programming, that's no big deal, but if you play a video, lagging will kill it.
I think HDMI is your best current option for refresh rate and lag. How about this:
http://www.ebay.co.uk/itm/HDMI-Driver-b ... 3a98ed4e6c

Or this?

http://www.ebay.co.uk/itm/HDMI-input-LC ... 3ce566ea96

khusro017
Posts: 1
Joined: Tue Jan 20, 2015 1:49 pm

Re: Building a protable pi

Wed Jan 21, 2015 8:46 pm

plz tell me how to install 7 inch tft touch screen lcd with raspberry pi.
i have a touch screen given in below link.

http://www.sainsmart.com/7-inch-tft-lcd ... a-2av.html

but now i dont know what to do.
plz tell me how can i install this lcd.

BMS Doug
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Location: London, UK

Re: Building a protable pi

Thu Jan 22, 2015 6:29 pm

khusro017 wrote:plz tell me how to install 7 inch tft touch screen lcd with raspberry pi.
i have a touch screen given in below link.

http://www.sainsmart.com/7-inch-tft-lcd ... a-2av.html

but now i dont know what to do.
plz tell me how can i install this lcd.
Connect hdmi lead from pi to lcd driver board. Connect lcd ribbon to lcd driver board.
Connect usb board to lcd driver board
connect usb lead between pi and lcd driver board.
connect 12v to lcd power input. Connect 5v to pi power input.
Doug.
Building Management Systems Engineer.

PiGraham
Posts: 3778
Joined: Fri Jun 07, 2013 12:37 pm
Location: Waterlooville

Re: Building a protable pi

Thu Jan 22, 2015 6:35 pm

khusro017 wrote:plz tell me how to install 7 inch tft touch screen lcd with raspberry pi.
i have a touch screen given in below link.

http://www.sainsmart.com/7-inch-tft-lcd ... a-2av.html

but now i dont know what to do.
plz tell me how can i install this lcd.
Did you watch the video? https://www.youtube.com/watch?v=ILBcgpW ... 1421828030

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scidata
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Re: Building a protable pi

Thu Jan 22, 2015 7:34 pm

Of course, if you have a notebook PC, the easiest way to make a portable pi is to just connect the two via ethernet cable. The notebook can then be the KVM for the pi (as well as the power source maybe). That's about as clean and portable as it gets.
"Self-education is, I firmly believe, the only kind of education there is" - Isaac Asimov

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