[Windell Oskay]

If you’re going to do this from within PeggyDraw, the first step would be to download the code, and make sure that you can run it without any modifications.

[Windell Oskay]

One way would be to use two tables — one for X, one for Y. 

[Windell Oskay]

The best location for the table will depend upon what your setup looks like. There is not necessarily any latency that would go along with it.

If you have a computer feeding video to the Peggy, then it will be fastest to do the lookup between generating the video frames and sending them to the Peggy.

If you have an animation stored on the Peggy (possibly made in the PeggyDraw 2 program), then it would be fastest to use the lookup table in the PeggyDraw 2 program itself– so that the animation frames are stored with the alternate mapping. 

[Windell Oskay]

First off, read this note about wiring off-board arrays with the Peggy 2: http://www.evilmadscientist.com/2012/mailbag-hacking-peggy/ 

Second, it’s still not clear to me in what context you want to remap the wires. The display is addressable– for whatever context you want send the data in, it’s also possible to remap the data before you send it. That is to say, where does that “A1” come from? D801 is just row 8, column 1. You can build a lookup table to do a mapping like that in any programming environment.

[Windell Oskay]

Can you please give a little context? Is this for a Peggy 2? And, in what context are you trying to “remap” it– are you trying to do this from within a particular program or programming environment?

[Windell Oskay]

You likely wouldn’t change anything on the circuit board– just add wires between the circuit board and the matrix.

[Windell Oskay]

As a starting point, download the datasheets for both matrices, and compare which pin does what on each matrix.

[Windell Oskay]

So, did you build this from scratch, starting with the Meggy Jr RGB PCB?  If so, make sure that you’re using a preprogrammed “Arduino” ATmega328 (such as the preprogrammed ones from our shop), not a “bare” ATmega328 from the manufacturer. 

In any case, that LED matrix has different internal wiring than the Betlux matrix– it’s sort of wired “inside out” compared to the other. If you look at the datasheets for the two matrices, you should be able to map how you’ll have to route the wiring to the matrix in order to get the display to work.

As for the cable, it’s very important to check the wiring order as I indicated, but you should also leave this for a secondary task *after* you get everything else up, running, and verified. 

[Windell Oskay]

Ah– didn’t read closely enough. That cable uses the PL-2303HXD IC — Windows can auto-download the driver for it. 

[Windell Oskay]

Once the kit is put together and powered on — assuming that you’ve finished assembly — there is a built-in (preprogrammed) game there, with lights and sound. You should definitely try and get to the point of having that working, so that you know that the hardware is put together correctly, *before* trying to program it… and it sounds like you need to stop there, and double-check everything.  If you did accidentally succeed and put some other program on it already, that could potentially make it much harder to troubleshoot any hardware issues.

With the buzzer not installed, you obviously won’t get any sound. By “option LEDs”, I assume you mean the row at the top.

I’ve never seen that programming cable before. I’m not sure what chip it has inside; it *may* require a driver to work properly. Also, you should check its pinout against a standard USB-TTL cable for comparison– there is no “green” and “black” end, so you’ll need to make sure that you’ve got the cable correctly oriented (and that the wires match up to what the normal order is).

[Windell Oskay]

*Ignoring* programming, can you please say whether the Meggy Jr is working correctly? Does it power up, and make light and sound?

Second, can you please say exactly what programming interface you are using? Is it the Adafruit FTDIfriend? Is it an FTDI cable? Something else entirely?

[Windell Oskay]

Is the Meggy Jr working correctly otherwise? You note that the chip is in the correct orientation — if that’s a concern here, then it seems like you may not yet be up and running otherwise.

And, exactly which programming interface are you using?

[Windell Oskay]

Quite a few people have just gone ahead and wired it up for USB power. The theoretical issue is that the Meggy Jr can draw more power than the port is rated for, with the theoretical consequence that it could destroy the USB port on the computer. However, most USB ports are power limited, and we’ve never heard of any actual ill effects from doing this. On the other hand, we can’t guarantee that it’s safe in all situations.

[Windell Oskay]

Use the same techniques that you would with any other op-amp.  The hard part is usually understanding what each of those terms really mean in the real world– once you do, it becomes somewhat reasonable to start to design your own tests with them. You might start with a few separate Google searches on how to measure those values.  

Here are some starting points for you:

 http://www.analog.com/library/analogDialogue/archives/45-04/op_amp_measurements.html

http://electronics.stackexchange.com/questions/58925/obtaining-an-op-amps-open-loop-gain

http://electronics.stackexchange.com/questions/73689/what-is-input-and-output-impedance-of-an-opamp

http://www.sengpielaudio.com/calculator-InputOutputImpedance.htm

[Windell Oskay]

Perfect. You might want to add a drop of hot glue in the middle of each jumper wire, to prevent the wires from getting eventually broken off.

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