backspace119 wrote:
GARTHWILSON wrote:
By "read the primer," do you mean the
6502 primer?
Yes, that's the one, and I may have misunderstood some of the information on the Displays section. From what I was seeing, there were plenty of options for text based panels or monochrome dot matrix panels but I didn't see a lot of info on color panels.
Yeah, I haven't gotten into color, partly because my applications have little use for color, and I don't want the complexity. I'll leave that for the game enthusiasts.
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I'm worried about using a serial line because the transfer rate for something similar to 256x256 at 8 bit color depth would be about 524,288 kbit per frame, so about 15.7 mbit per second for 30 fps. I would be worried I couldn't achieve this kind of bandwidth but I could use some of the tricks I mentioned above on a serial line to greatly reduce the bandwidth load
Daryl's 65SPI IC shifts a byte in and one out (SPI goes both directions simultaneously) in 16 clocks. You'll probably need that much time just to handle each byte during the process anyway; so it wouldn't be slowing you down. He is re-working the design for a newer CPLD since the old one became unavailable. I still have several here I could let go of. The 6522 has a synchronous serial port that's just as fast, although not bidirectional. A few people have used it for one of the SPI modes. I'd have to sharpen my pencil to see what tricks (if any) there might be to using it for SPI.
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GARTHWILSON wrote:
Many of the LCD modules have a fair amount of intelligence built in, and can do things like limited scrolling which would take care of panning without having to re-write all the pixels over the interface. There are also add-on boards for some LCD modules which add things like text capability so you don't have to calculate which pixels to turn on for text. Just tell it where to start and give it the ASCII of what to display. A module (or its add-on board) may hold many pre-formed frames in its own memory so if there are several that you use all the time, you can tell it to just bring up a particular one and then you only change a small amount of it.
I'm not certain how scrolling actually works on a per-pixel basis to be honest,
The monochrome graphics LCD I've used, and another I plan to use, take a command to tell which dot row and column to start with in its internal memory. In this one, it wraps IIRC, so you would have to re-draw just the one row or column that wrapped around to the other side or end. I know I've seen other ones though that have an internal memory that's larger than the screen, so there's a certain amount of panning you can do without re-drawing anything.
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without the use of sprites that is. I was actually planning on using an add-on module for the text, because from the primer I seem to remember they were mentioned, and it should make ascii a lot easier, I was only worried that it would be hard to integrate with the type of display I'm trying to use. As far as the pre-formed frames, I'm a little confused on this part, do you mean like the map frame I could leave loaded and then draw stuff over top of it without much effort?
Yes, just change the bytes you want to, and take advantage of the rest already being what you want.
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Overall, I'm just very cautious about buying parts and putting something together that doesn't work, especially since the only oscilloscope I have was one that my grandfather built in trade school in the 50s that he gifted to me (and the horizontal hold doesn't even work on it). And I'm also very budget-oriented on the build presently,
You can often get free dual-trace, triggered CRT oscilloscopes that businesses or schools are getting rid of, in the range of 20-100MHz. Do yourself a favor and get a decent scope. One of these will be way better than most of the cheap new digital ones like the worthless DSO Nano you hook to your computer, and certainly better than the scope from the 1950's. Just be sure to get a decent pair of 10x probes with it, and take care of them. Good probes are not cheap. There's a lot more there than meets the eye. (The 6502 primer's
section on basic workbench equipment discusses this.)
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And thanks for writing and providing the primer for people just getting into this like me, it really is a wealth of information
You're welcome. It was written to answer a lot of questions and problems that kept coming up over and over in the early years of the forum. It does get frequent small updates. The whole site probably has a thousand links, and I definitely can't check them all every week; so if you find that one has gone dead, please let me know.
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(does 5v give better clock stability as well?)
It's mostly unrelated. If anything, a lower voltage may cause less trouble, because parts are the fastest at their maximum voltage, producing faster edge rates that are more likely to cause ringing and double triggering, and also responding more quickly to it and being less forgiving.
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For surface mount, I can solder by hand and I have a hot air kit and can source solder paste if needed (I've been wanting to build a paste dispenser for a while anyway), I realize I'll probably need to build a reflow oven to do it as well, but adafruit (I believe) had a pretty neat hack for a toaster oven based reflow oven that I might try. Ultimately, I'd like to stick with THT as much as possible though, for both the look and the ease of use (and easier to find sockets)
There are of course thru-hole sockets for PLCCs. Remember also that if you need additional parts or connections on the other side from a DIP, you can forgo the holes and just put pads down on the board to solder the DIP to, holding it on with solder fillets. That should be fairly easy to unsolder too, using solder wick.