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MVS-99-6 - Project on hold until further notice (2014-03-10)
Yvan256:
I was able to find a Donkey Kong Jr. marquee in EPS format, the colors seem indeed much better IMHO.
Yvan256:
I need funds to help buy parts such as that 1.8" LCD, so I've listed my 6-slot MVS board for sale on eBay.
I also have Samurai Shodown with mini-marquee, Samurai Shodown II with mini-marquee and Crossed Sword (cart only) for sale, though I would like to at least keep the Samurai Shodown or Crossed Sword cart until this project is over to make a "comparison photo" for the size reference.
edit: 1.8" LCD ordered with the help of one of my best friend.
edit 2: package left Solarbotics in Calgary.
edit 3: package is supposed to be on its way.
Yvan256:
The new 1.8", rectangular TFT LCD for the mini-marquee has arrived, along with some other parts. :cheers:
You can see the footprint of the two PCBs are nearly identical in height but the new LCD display is taller.
Included is a comparison between a Neo-Geo marquee displayed at 130x130 vs 128x160. Less black = better Neo-Geo mini-marquee ratio.
Yvan256:
After a bit of research, I've decided that TIFF is way too complex for the code space and RAM available in the ATtiny861.
So after some reading I've decided to go with the TGA file format for the marquees. It's a fixed 18-bytes header followed by the pixel data itself (for 24-bit color images anyway). Couldn't be any simpler, even BMP is more complicated. Even if there's variations, I don't care since it's a closed system where I control which images are used.
Preview, on Mac OS X 10.5, can save TGA but only with RLE compression, meaning it's quite simple to de-compress on the fly and doesn't require huge amounts of buffering to decode either. Worst case scenario, the TGA format also supports uncompressed images so all I'll have to do is find software to save them as uncompressed TGA.*
I'm currently wiring and coding for the new LCD and compressed TGA graphics, I should have photos in a few hours days.
* I did some tests on a web page with PHP and I was able to decode RLE-compresed TGA graphics with no problems. Apart from the graphic data itself it only takes eight 8-bit variables for the whole thing if I limit the decoding logic to the size of my new LCD display. ;D
Attached is a picture of the Donkey Kong, Donkey Kong Jr. and Bubble Bobble marquees:
* Left picture: RLE-compressed pixels
* Middle picture: non-compressed pixels
* Right picture: all pixels, resulting in the final graphic
Of course, it's all done in one pass when it's decoded but I thought some graphics might help understand RLE compression for non-coders.
Yvan256:
I'm not even done with initializing the LCD and I'm almost running out of code space. :P
Never mind accessing a microSD card via FAT16 and communicating with the computer via the serial port. :cry:
So... long story short, I've switch to another microcontroller I already had laying around, ATmega644P. This one has eight times more code space and RAM than the ATtiny861, it should be enough for everything. As a bonus, I'm gaining a real UART (for the serial port connection) and two more SPI ports (if I use another SD-card interface I got here, I should be able to both read from the SD card and write to the LCD at the same time).
I could even have enough code space left at the end to store the MVS logo as a "boot screen" (currently takes 14162 bytes as an RLE-compresed TGA file).
Below is the obligatory photo of the current setup. For those into electronics, you might be wondering how many rows of pins are free on the breadboard. There's none. It's a 30 rows breadboard, the ATmega644P takes 20 and the LCD takes 10. :o
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