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1  Community / Products and Services / Arduino compatible sensor boards available on my eBay on: April 13, 2014, 03:41:16 pm
I have now listed a few of these since they are popular.

Compass sensor
Acceleration sensor
Rotary Encoder

If you search a lot + wait upto one month, you can even get these for a little lower price.

Besides, I have now a multivariation listing for LEDs and Microcontrollers on ebay UK.
On US eBay these kinds of listings are not possible at all.

Shipping to UK/Europe : a few days.
to USA: About a week, sometimes 5 days.
2  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 15, 2014, 12:49:26 am
Since I have serial RAMs here I will try it. Thanks for the idea, 32K is just enough for 128x128 at 16bits/pixel.

They are not compatible with the TFT. First I need to write to SRAM only, then copy to the TFT.
3  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 14, 2014, 07:30:55 pm
The parallelel mode has the R/W line I was talking about. Also, the parallel ram concept would depend on you knowing the memory map of the display.

Hmm, of course I know the memory map? I want to display a moving cursor as said above.
One solution is to maintain a smaller tiles memory, and update again, easy if it is graphics, not so easy if it is text from a font, and what if I draw lines and stuff?

I think I will just use the larger 2.4" TFT.

Why it is not possible to read back data? For a cursor it would only be a small number of pixels. All these small TFTs have serial interface only (which of course is handy for wiring).
4  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 14, 2014, 05:59:37 pm
Well yes I have 32K serial RAMs here but I'd need at least two and it's a lot of effort.

I was thinking maybe the 1.8" TFT would work since the line about write only is not found.

going to change to larger chip/2.4" TFT anyway.

In the meanwhie, I am wiring up the small OLED, it has all pins laid out so it can be used in parallel mode.
not so much FLASH left after adding the SD card file system, only about 30% from 32K.

Since I saw today in the OLEd pdf it is write only in serial mode, eventually all of these displays are write only in serial mode.
5  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 14, 2014, 03:15:59 pm
Today I saw the OLED PDF explicitely metions the serial mode is write only.
6  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 14, 2014, 02:53:42 pm
From what i just saw in a PDF for a OLED, the serial connection is really write-only.

By the way the PDFs are available at the URLs above. I have also uploaded them to my blog for easier access (no unzip).

So you kinda say, even without having used the displays, you'd be able to help?

As i say, one of the PDFs contain a line serial mode is write only, while the other doesn't.

Maybe i have to live with that, and build another circuit with a parallel controller.

How can I maintain a cursor on the TFT, if I can't read back? The only way would be to maintain a tile buffer or to use text only, but it would be complicated to code.

7  Using Arduino / Displays / Re: Reading back from 1.44"/1.8" TFT on: March 13, 2014, 05:10:49 pm
The 1.44" TFT
The 1.8" TFT

I have the 1.44" TFT working, but as said, can't read back. The 1.8" controller PDF has many pages appearing almost identical. But the line it can not read back IS NOT present.

So, I wanted to get a response if anyone has ever succeeded to read back from either one of these 1.44" or 1.8" displays.
8  Using Arduino / Displays / Reading back from 1.44"/1.8" TFT on: March 13, 2014, 09:18:03 am
These TFTs are well known, serial interface.

In the 1.44" TFT datasheet there is a line the read command only works with parallel interface.
i tried, but when I attempt to read data, the TFT no longer updates the display.
When I restart next time, I see the updates written to the TFT RAM tough, and they display.

How about the 1.8" TFT? Reading back from the RAM is possible or not?

The datasheets are somehow very identical, even if the chips have different manufacturer/type number.

The only other alternative is to switch to use a larger, parallel TFT with 2.5".

I want to move a cursor on the TFT with a playstation XY encoder, and for that I really need to read the pixels under the cursor, and restore them.
9  Community / Products and Services / Serial LED displays now available for sale on: March 07, 2013, 09:23:56 pm
I have finally made the firmware working to a degree the displays are easy to use.

3-wire serial interface.
At first the display is reset, then it is waiting for a serial data stream.
After all neccessary bits are transfered, the display starts lighting up.

Due to technical reasons, each reset takes about 20 milliseconds.

The serial transfer is relatively independent from the actual used controller.

More information here, including source code to use the displays.
C language is used, so it should be very easy to adapt to Arduino.

It is a synchronous serial transfer.

These displays make circuits much easier and faster to build, as well smaller and cheaper.

Starting at $3.98 for 3 digits!

More info here:

If requested, I have a micro Arduino here, and could adapt the C source to this platform.
It is however not dificult to do I think.

These displays are available now and have been tested.
Developement time was about 2 years.

Indeed any multiplexed LED diplay can be used with upto 12 pins.
Not limited to 7segment displays!

The displays work best at 3V however also can be used at 5 volts.
It is either possible to change the firmware a little so they are less bright,
or use them with high brightness.

I will accept requests to code the data tables for any 7segment display,
preferably if you buy more than one display.
All I need is the datasheet and a sample if possible. Or information where to buy a sample display.

I have available here 4digit displays and 3digit displays, but can offer other colors than red if there is demand.
10  Using Arduino / LEDs and Multiplexing / Re: 74HC595 and LEDs on: April 04, 2012, 03:06:42 pm
I mean Grumpy_Mike, I use 2.2k resistors for each LED, and 4x switching.

So my circuit is totally on the safe side at 5 volts! Guarantee.  smiley-sweat

I'm happy that I can know it's total correct circuit.
11  Using Arduino / LEDs and Multiplexing / Re: 74HC595 and LEDs on: April 04, 2012, 03:05:02 pm
Yes it's poor wording from a poor Windows programmer soul.

I have good news: use 4x 2.2k Ohm resistors is OK for modern clear LEDs.

So the OP has no need to bother about my precautions. Think Grumpy_Mike many other people will read this thread. So I only add relevant additional info.

The Answer to the OP realy is: Yes it's safe for my purposes. If you know what can go wrong, it can be safe. If you don't have the LED datasheet, or a beginner, IT IS NOT SAFE.

You see Grumpy_Mike it's difficult to give a valid answer, unless you think backwards, only to satisfy people who are new to this technology. Is this a teacher or school technique?
12  Using Arduino / LEDs and Multiplexing / Re: 74HC595 and LEDs on: April 04, 2012, 02:38:30 pm
there are 10 to 20 factors that limit current, otherwise the IC (Arduino) would really use 3 Amps, using 10 pins shorted to ground. It would pop up instantly. There are limiting factors but different from using LEDs, shorting too many I/O will destroy most smaller controllers.

The lowest gap, 0.5 volts, has really large increase in current. What becomes the limit then are the MOS channels, to the current distributes. They work like resistors and that's OK for them. 120 ohms, but i do not know it can change due to voltage. not a ohm resistor.
13  Using Arduino / LEDs and Multiplexing / Re: 74HC595 and LEDs on: April 04, 2012, 02:28:03 pm
This is the rating for the continuous current.
If you use 6x multiplex, it's only 16.6% modulation.

A trick is to use 4 LEDs on the H drive and 4 on the L drive.

At 3 volts the currents are lower than 20mA, so it can work 50% or 100%.
14  Community / Bar Sport / Re: Laws of the Forum on: April 04, 2012, 02:16:01 pm
On the positive side, many members strike a commendable balance between giving the answer and giving the information to find the answer. In the short time that I have been around the forum I have never seen it formalised anywhere, it just seems to be the spirit of the forum, its great, keep it up.

Duane B

Every living forum has a hidden self-inherent purpose or goal.
Usually these include to cooperate towards financial improvement.
So you lay out your action that all people can do their business without too much trolling or distrubing on purpose.

Trolls randomly add adverts, unrelated random word chains containing url's, and one big brand sign of trolls is spelling URL's two times.

They can bring down a forum if they become too many.

And every forum originally needs a critical mass to start off.

From zero, forums take years even to have a few members.

So it's often inherent from the original core group.

Generally, forums contain automatic rules that enforce sense of community, common sense, and kind of self censorship. Other's unfortunately really allow graphical violence and this qualifies communities as unprofessional.

Every social and friendly forum should declare "About Us", including where the admins come from. At least the country, and what they do for a living. You can't really trust made up handles.

The admins here on Arduino have at least experienced a moderation process, that made them Admins.

Some admininstrated forums are sensible against any kind of pattern that they have not seen before. So if a new member starts to talk in a pattern they don't know, and correlations they don't understand, these people get into trouble.

That's really a complex digital feedback network that interacts with the human mind, but there are some theories about these dynamics.
15  Community / Bar Sport / unique SMD LEDs that need "burn in" using high current on: April 04, 2012, 02:00:19 pm
Hello I wonder what is the reason for this, or how is this possible technically?

These are very small SMD LEDs, that after soldering, don't glow very bright. As if they were damaged from high temperature. Some were brighter, ans quite normal.

Now, I tapped them with shorft 5v volts pulses manually (1/2 second or so).

Then these LEDs would sudden increase 5x in brightness, and remain at this level.
When I use lower voltage later, they are still high brightness!

As if the phospors or the Gallium were "heat cured". or no, let say, "high current cured".

It really worked that way!

Still have some reel cuts of these, new.
They are way too small for human soldering.

I tried with half-size SOT23 PNP transistors, but gave up the project after soldering 15 LEDs.

Maybe 4 years ago? This piece is long gone.
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