Iboard and DMD

The Dot Matrix Display (DMD) is a 32x16 array of high-brightness LEDs for visually striking effects. [Product Page]
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celestin
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Iboard and DMD

Post by celestin » Tue Nov 19, 2013 2:51 pm

Greetings to all of you!

Please help me with this issue I am having with my DMD.

I am trying to control it using an iBoard (http://imall.iteadstudio.com/im120410001.html), I am using for connection the pins A0-A5 and I've modified the values DMD.h. The only problem is that I am not getting anything to be displayed on the DMD.

All the best,
Celestin

andrew
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Re: Iboard and DMD

Post by andrew » Tue Nov 19, 2013 9:03 pm

Hello
Have you connected your DMD to external power?
Problem is with your iBoard - it uses 3.3V I/O whereas the DMD is designed for 5V. Although some have had success with 3.3V I/O such as with a Raspberry Pi, the DMD could be causing a brownout due to the inability of the iBoard to power the MCU, Wiznet chip and so on.

Furthermore the DMD is basically an SPI device, so if you don't have any luck after the power suggestion, restore the DMD library to original state and connect it to the required digital pins - looks like you might need to hack the iBoard up a bit to do that.

Finally there are a few forum members who have worked on bit-banging to the DMD without the SPI pins, have a search through the forum for these discussions.

celestin
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Re: Iboard and DMD

Post by celestin » Wed Nov 20, 2013 7:30 am

Yes, of course I've connected the DMD to an external power supply.

The Iboard only gives me the pins A0 to A5 to connect the DMD. In the library there is also the pin 10 but it's not connected to anything.

Regarding raspberry PI, we are controlling 8 DMD's with one Raspberry PI and everything works smooth.

The issue is that I want to control the DMD using a board that has Ethernet connection. I was thinking at an Arduino Nano + ENC Ethernet module, but I really preffer the iBoard.

celestin
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Re: Iboard and DMD

Post by celestin » Thu Nov 21, 2013 12:46 pm

Still one more question: If my IBoard uses SPI for other devices, is it possible that the pins A0-A5 can't be used for SPI with the DMD?

andrew
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Re: Iboard and DMD

Post by andrew » Thu Nov 21, 2013 9:54 pm

celestin wrote:Still one more question: If my IBoard uses SPI for other devices, is it possible that the pins A0-A5 can't be used for SPI with the DMD?
You can still use SPI on the normal pins, as the library will have to be modified to use A0~A5. You may want to reconsider the choice of board to one that has all the digital pins broken out.

celestin
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Re: Iboard and DMD

Post by celestin » Wed Nov 27, 2013 10:45 pm

Well I've managed to control it with the iBoard, beacause I found the pins for SPI.

Now I have another problem, the iBoard has the Wiznet W5100 chip on it. I want to read a txt file from a webpage and then display it on the DMD. How can I do this?

andrew
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Re: Iboard and DMD

Post by andrew » Thu Nov 28, 2013 9:36 pm

celestin wrote:Well I've managed to control it with the iBoard, beacause I found the pins for SPI.

Now I have another problem, the iBoard has the Wiznet W5100 chip on it. I want to read a txt file from a webpage and then display it on the DMD. How can I do this?
Reading a webpage can be tricky. However it can be done. You need to scrape the text then place it in a String variable for display on the DMD.

celestin
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Re: Iboard and DMD

Post by celestin » Fri Dec 06, 2013 12:42 pm

The problem is that when I try to access the WIZNET, the DMD flashes or displays ambiguous informations...

angusgr
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Re: Iboard and DMD

Post by angusgr » Wed Dec 11, 2013 10:14 pm

Hi celestin,

In the DMD.h file in the DMD library there's a line like this:

Code: Select all

#define PIN_OTHER_SPI_nCS 10
If you set this to the CS pin that that W5100 uses, it should stop the flickering update problems.

Please let us know how you go.

- Angus

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