Storing user data on your FPGA

We’ve seen FPGAs used to recreate everything from classic arcade games to ancient computers, but with each of these builds a common problem arises. Once you’ve got the hardware emulated on an FPGA, you’ve also got to get the ROMs into the project as well. In a very interesting hack, [Mike] figured out that the serial Flash chip that stores the FPGA settings has a lot of space free, so why not store user data there?

[Mike] got the idea from seeing a recreation of the classic BombJack arcade game we featured last month. In that build, [Alex] needed to store 112Kb of game data stored in 16 ROM chips. Unfortunately, [Alex]‘s FPGA only had space for 40Kb of data. After realizing his FPGA had a 512Kb SRAM chip, [Alex] decided to put all the sprites, sounds, and levels of BombJack in the SRAM.

Impressed with [Alex]‘s build, [Mike] set to work generalizing the hack to work with other projects. [Mike] notes that only a few FPGA boards are capable of storing user data next to the  configuration bitstream; the hack is impossible on the Digilent Basys2 board, but it works wonderfully on a Papilio One 250K.

As a very cool build that makes FPGA-related builds even easier, we’ve got to tip our hat to [Mike] for writing up a great tutorial.

Digital picture frame reverse engineering

coby_frame_hack

A few months ago [Jason] got his hands on a free Coby DP700WD digital picture frame and thought it would be fun to hack. After realizing that the frame did not run any sort of Linux-based OS he figured his options were pretty limited, but he gave it a shot anyways.

The frame came with a set of built in images, and his goal was to swap them out for pictures of his own. He started by trying to read data from the frame’s serial flash chip, but found that the processor was preventing him from doing so. He de-soldered the chip from the frame, mounted it on a makeshift breakout board, and started reading up on SPI.

He was eventually able to read the device’s flash chip and swapped out the built-in images with his own. After a bit of trial and error, he was able to replace the frame’s boot screen with his own custom image as well.

If you are looking to do something similar, be sure to swing by his site – all of the tools and code he used to hack his frame are available for the taking.

Continue reading to see his modified picture frame in action.

[Read more...]

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