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by tummychow
Tue Jun 04, 2013 12:03 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Which expansion board(s) to interface these...
Replies: 8
Views: 2898

Re: Which expansion board(s) to interface these...

Hm, I was going to suggest that you look for GPIO expanders, but the devices you want to use are a bit more... exacting. Let's start with the easy stuff. Five pots, no problem. MCP3208 or something will clean that up easily. 8 channels of 12-bit analog input is more than enough for reading a pot. Yo...
by tummychow
Mon Jun 03, 2013 11:42 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Cheap I/O Expansion chips
Replies: 16
Views: 11014

Re: Cheap I/O Expansion chips

There's only one place you need to look: http://www.digikey.com/product-search/en/integrated-circuits-ics/interface-i-o-expanders/2556690 Digikey is arguably the premier online part distributor (other good, borderline-universal distributors include mouser and farnell/element14/newark) and they have ...
by tummychow
Sun Jun 02, 2013 9:26 pm
Forum: Other projects
Topic: Cell Phone screens
Replies: 2
Views: 5066

Re: Cell Phone screens

Your best bet is to just search these forums - if someone's doing it, they've probably posted about it here. It's going to depend a lot on the screen, but I'd hazard a guess that many modern smartphone screens, being fairly large and pretty, have long parallel databuses, maybe 16+ data lines. The PS...
by tummychow
Fri May 31, 2013 11:53 pm
Forum: Other projects
Topic: Screen
Replies: 1
Views: 632

Re: Screen

I also want it to be pretty cheap then you better start shopping. Any screen in that size with a connector already onboard will probably be for a car or something... I could have sworn I'd seen them in the sixties of dollars before, but everything I can find right now is 120+ USD. Over triple the c...
by tummychow
Thu May 30, 2013 2:39 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Driving LEDs from GPIO input pins?
Replies: 8
Views: 7891

Re: Driving LEDs from GPIO input pins?

My question is, is it OK to drive LEDs from voltage coming into the input pins (see simplified schematic here: https://www.circuitlab.com/circuit/79k7wt/screenshot/1024x768/ ? I figure about 2mA (LEDs will be pretty dim, but that's OK) will make it to each of the LEDs (x8 inputs), well within the 5...
by tummychow
Thu May 30, 2013 2:31 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Connecting DSI to CSI
Replies: 2
Views: 1011

Re: Connecting DSI to CSI

(with appropriate drivers, perhaps) The word you are looking for is "magic", not "appropriate" (ie "with magic drivers, perhaps"). The DSI port is controlled by a closed driver in the GPU, not end user editable at this time. I'm not sure about the CSI port's protocol s...
by tummychow
Thu May 30, 2013 2:25 am
Forum: Other projects
Topic: Nintendo DSi Screen?
Replies: 2
Views: 6635

Re: Nintendo DSi Screen?

Is there any way to connect the Nintendo DSi touch lcd to my Pi? Depends, see below Can I use the Display serial interface port on my pi? 100% no. Drivers for this port are in the GPU binary blob, and that blob is 100% closed source; we're a very long way from editing that ourselves. Will it be dir...
by tummychow
Wed May 29, 2013 12:36 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Cheap I/O Expansion chips
Replies: 16
Views: 11014

Re: Cheap I/O Expansion chips

If your concern is prices, there are much better ways than ebay. Remember that ebay prices are usually extremely high per unit (I find it's usually well over 100% markup), and the "free" shipping is being subsidized into the cost over their thousands of low-volume orders. There are better ...
by tummychow
Sat May 25, 2013 1:16 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DSI LCD
Replies: 14
Views: 37621

Re: DSI LCD

It doesn't matter if you know how the hardware works. Again, you cannot actually write the driver. DSI is a physical interface, ie it simply refers to the way the connector is formed (plus a few standard instructions and pinouts, but the standard bits aren't enough to make a screen work, they're thi...
by tummychow
Fri May 17, 2013 11:55 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DSI LCD
Replies: 14
Views: 37621

Re: DSI LCD

The screens and displays section of the forum probably spends about half its time discussing raw-pin TFT displays (the other half is spent discussing the kinds that plug in). http://www.github.com/notro/fbtft is a good place to start. The wiki on his github project lists a lot of the details if this...
by tummychow
Fri May 17, 2013 11:52 pm
Forum: Other projects
Topic: GPIO and screens
Replies: 12
Views: 17706

Re: GPIO and screens

would a standard ribbon connector be all I needed to connect the raspberry to that screen? Ain't no such thing as a standard ribbon connector =P a ribbon connector is (generally) just a bunch of wires next to each other with a convenient connector on either end that lets you plug into the devices a...
by tummychow
Fri May 17, 2013 11:39 pm
Forum: Other projects
Topic: Pi + GBA SP TV out and 240x160
Replies: 6
Views: 4787

Re: Pi + GBA SP TV out and 240x160

Excuse my utter noobiness - just want to know how simple this would be to use as the Pi's screen. Been looking for a tiny screen for my Pi for a while, and I've not seen much beyond vast amounts of programming. Just want a tiny screen, that's as close to plug-and-play as possible. The small ones al...
by tummychow
Fri May 17, 2013 11:31 pm
Forum: Other projects
Topic: Display
Replies: 1
Views: 710

Re: Display

Half the size of an iphone screen is very small. You're only going to find screens of that size if you look at ones with the pins exposed, and the burden is on you to write a driver that teaches your GPIOs to control it. http://www.github.com/notro/fbtft is a good place to start. Take a look at the ...
by tummychow
Fri May 17, 2013 11:23 pm
Forum: Other projects
Topic: Hooking up QVGA touch screen
Replies: 3
Views: 3521

Re: Hooking up QVGA touch screen

It's not easy, but to be fair, I think you're overblowing the difficulty of getting drivers. If you're unlucky and your parts have never been seen in this forum before, then you'd be on your own, but there are plenty of drivers for touchscreen controllers (there's one for the TSC2007 somewhere on he...
by tummychow
Wed May 15, 2013 11:01 pm
Forum: Other projects
Topic: Hooking up QVGA touch screen
Replies: 3
Views: 3521

Re: Hooking up QVGA touch screen

first thing you need is information on the screen itself. What chip is inside? How do you talk to aforementioned chip? How many GPIO lines does it require? If you know how to talk to the chip, you can make a driver to put X on it (although I have no idea how to write the drivers; it's not exactly an...
by tummychow
Tue May 14, 2013 11:31 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DSI LCD
Replies: 14
Views: 37621

Re: DSI LCD

you can find a TFT with open pins that can be wired via GPIO, and it will probably be cheaper than the LVDS/HDMI adapter (look on ebay - probably 20 dollars or less), but you'll have to make some driver code for the screen if it doesn't already exist. As ghans mentioned, the dsi connector is control...
by tummychow
Tue May 14, 2013 11:28 pm
Forum: Other projects
Topic: LCD circuit
Replies: 27
Views: 9652

Re: LCD circuit

Is it possible to use a NPN transistor when the line has to be pulled to +3.3V? If you refer to this display: http://www.adafruit.com/products/335, it is wired differently. ITDB02.28 has LEDA brought out to the header through a 100R resistor, and LEDK{1,2,3,4} wired to GND. Adafruit 2.8 has LED-A w...
by tummychow
Sun May 12, 2013 10:25 pm
Forum: Other projects
Topic: LCD circuit
Replies: 27
Views: 9652

Re: LCD circuit

Could you please send an example circuit how to wire it? Which transistor are you recommend? If you're already familiar with how bipolar (BJT) transistors work, then wiring should be straightforward. a 2N2222 will work fine for this job. Adafruit's version of this board uses one. It also lets you P...
by tummychow
Sun May 12, 2013 10:23 pm
Forum: Other projects
Topic: Would this screen work?
Replies: 4
Views: 1194

Re: Would this screen work?

yeah, using an expander on parallel buses that have this many pins is usually a big speed cost. it'll take a while to draw frames (relatively). I also can't tell what controller that screen uses (I couldn't find it on that ebay page... maybe someone else saw it?) so it's not really clear how you wou...
by tummychow
Wed May 08, 2013 10:57 pm
Forum: Other projects
Topic: 4.3" composit display powered with GPIO
Replies: 2
Views: 1551

Re: 4.3" composit display powered with GPIO

Take a closer look at the specs of the display. Looks like it's driven by a boost converter lifting all voltages up to probably around 12V. You can't get power for free (and here I mean the rigorous scientific definition of poewr, ie the rate of energy transfer in watts), so if you feed the device w...
by tummychow
Tue Apr 30, 2013 5:26 pm
Forum: Automation, sensing and robotics
Topic: PWM outputs
Replies: 20
Views: 60207

Re: PWM outputs

as was mentioned in the other thread you made, the proper way to control DC motors is typically with an H-bridge, eg L293D. If you have a servo that demands more PWMs than the Pi provides, I hear the software implementations are pretty good (based on DMA, i think, so pretty stable), but you can easi...
by tummychow
Sun Apr 28, 2013 10:54 pm
Forum: Automation, sensing and robotics
Topic: Battery with 5V regulator - Safety & Power Usage
Replies: 19
Views: 4814

Re: Battery with 5V regulator - Safety & Power Usage

as peterO said earlier, the best way to reduce power consumption in your setup right now is to replace the 7805 with a switching regulator. It's not the Pi that's wasting most of the power here; your linear voltage regulator discards the top 7 out of 12 volts as heat - less than 50% efficient. A swi...
by tummychow
Fri Apr 26, 2013 10:07 pm
Forum: Other projects
Topic: Resistive Touchscreen (5-Wire) connected to the Raspberry Pi
Replies: 3
Views: 6476

Re: Resistive Touchscreen (5-Wire) connected to the Raspberr

Wow, this is actually quite intriguing. I knew AVRs could be used as touchscreen controllers since they have an ADC, but I had never actually considered the possibility. One big advantage I see for this solution is that AVRs often come in DIP packages which is very useful for the hobbyist (where as ...
by tummychow
Thu Apr 18, 2013 1:07 am
Forum: Other projects
Topic: Touchscreen?
Replies: 2
Views: 1066

Re: Touchscreen?

I don't have the particular screen you're thinking of, and I haven't seen any specific reports of success regarding it, so you're going to need some more information than that if you want to connect it to the Pi. As with all raw-wire LCD panels, what's the bus? How many lines? What are the commands ...
by tummychow
Fri Apr 12, 2013 1:19 am
Forum: Other projects
Topic: China 4,3" rearview monitor hacked open
Replies: 3
Views: 1591

Re: China 4,3" rearview monitor hacked open

When you say "power the pi", do you mean, "supply 5V through this device"? Because you probably shouldn't do that without knowing how much current it can push and how clean the regulation is. You might get unexplained dropouts from poorly regulated 5V, or maybe it can't push enou...

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