μblog: engineering from the trenches

After talking to the manufacturers of the eeprom programmer, we both decided that I should send it back to have it checked/replaced, so no rewritable roms for a week or two. In the mean time, I found a copy of Super Mario Brothers 3 at a local shop. I also decided to open the NES and follow the connector re-conditioning directions for the best experience. Now it’s time to get the power up and win the game.

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I modified two cartridges today, one that is based on a memory-mapper-less cart which holds two 28HC256 EEPROMs (32KByte) and one based on MMC1 which holds two 49F002 flash chips (256KByte.) When it came to testing the cartridges, it was also a good time to test the programmer for the first time, which was not recognized by two separate machines. Their software download site states that there is a new software update today and we should hold off on downloads, so I will wait for the update to see if that works. If not, then its time to send this programmer back and look for something else. I could pull out the old LabView programmer, but its getting late, and there is beer to be drank.

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After spending all those hours writing LabView code to program Atmel 8051 chips as well as EEPROMs, I now have access to a universal DIP programmer. This thing is supposed to be able to program almost any kind of chip (memories, PLD, MCU) that is dip and can be programmed and even some other chips through in-circuit programming capabilities. With this in hand, I can either modify my MMC1 (Nintendo memory mapper v1) and try loading a MMC1-based NES rom onto it or try to find a MMC3 cartridge somewhere and put a MMC3 game on it. (According to Kevin Horton, the only MMC2 video game was Mike Tyson’s Punch-Out and the higher end games are more complicated to design re-programmable cartridges for.) Maybe there is an easier way to get a copy of Super Mario Brothers 3? (If you have it and don’t mind giving it to me, let me know!)

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I have started playing with NES again and have thought about making a re-programmable cartridge since it could be possible to put in EEPROMs instead of the PRG and CHR chips. I will have to look into the ROM file mapping to the chips and modify my parallel EEPROM programmer program accordingly. Below are a pair of files which outline the chip pin-outs and the mapper which are originally from www.tripoint.org/kevtris by way of www.raphnet.net. More on this later when I get the circuit together.

rom.txt NES_ROM_Pinouts.txt

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So I have seen several examples of interfacing microcontrollers (PIC and msp430 specifically) to a TV by way of composite video out, but these examples have all been light on technical details in the way of explicit timing diagrams for these video signals. The motivation for making this interface is the inherent simplicity as we can create a basic black and white composite signal by connecting two digital I/O pins together through a pair of resistors, so, it is fairly easy to add video support to almost any microcontroller project and thus bring about a sense of nostalgia. First, I will explain the basics of composite video and then demonstrate a simple improvement to the system. (more…)

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