Breaking out the Sega Saturn out of the closet for a hit of 90’s nostalgia comes with its own set of compromises: the wired controllers, the composite video, and worst of all that dead CR2032 battery behind the backdoor. Along with the death of that battery went your clock and all those precious hours put into your game save files. While the bulk of us kept feeding the insatiable SRAM, a friendly Canadian engineer named [René] decided to fix the problem for good with FRAM.
The issue with the battery-backed memory in the Saturn stems from the particularly power-hungry factory installed SRAM chip. Normally when the console is plugged-in to a main power source the CR2032 battery is not in use, though after several weeks in storage the battery slowly discharges. [René’s] proposed solution was to use a non-volatile form of RAM chip that would match the pinout of the factory SRAM as close as possible. This would allow for easier install with the minimum number of jumper wires.
Enter the FM1808 FRAM chip complete with a whopping 256 kB of addressable memory. The ferroelectric chip operates at the same voltage as the Saturn’s factory SRAM, and has the added benefit of being able to use a read/write mode similar to that of the Saturn’s original memory chip. Both chips conform to a DIP-28 footprint, and only a single jumper wire on pin 22 was required to hold the FM1808 chip’s output-enable signal active-low as opposed to the active-high enable signal on the Saturn’s factory memory chip. The before and after motherboard photos are below:
After a quick test run of multiple successful read and writes to memory, [René] unplugged his Saturn for a couple days and found that his save files had been maintained. According to the FM1808 datasheet, they should be there for the next 45 years or so. The only downside to the upgrade is that the clock & calendar settings were not maintained upon boot-up and reset to the year 1996. But that’s nothing a bit of button-mashing through couldn’t solve, because after all wasn’t the point of all this to relive a piece of the 90s?
The Internet of Things is here in full force. The first step when adding to the Internet of Things is obvious, adding a web interface to your project. [Jaspreet] wrote in to tell us about his project that adds a web interface to his MSP430 based project, making it easy to add any project to the internet of things.
Creating a web interface can be a bit overwhelming if you have never done it before. This project makes it easy by using a dedicated computer running Linux to handle all of the web related tasks. The LaunchPad simply interfaces with the computer using USB and Python, and the computer hosts the webpage and updates it in real time using Node.js. The result is a very professional looking interface with an impressively responsive display that can control the on-board LEDs, read analog values from the integrated ADC, and stream accelerometer data. Be sure to see it in action after the break!
“Energia is an open-source electronics prototyping platform … with the goal to bring the Wiring and Arduino framework to the Texas Instruments MSP430 based LaunchPad.” The newest release of Energia is exciting for the sole reason that the new TivaC Connected LaunchPad and Wolverine FRAM LaunchPad are supported. The TivaC Connected LaunchPad is a $20 development board for TI’s low-power ARM processors that has Ethernet connectivity. The MSP430 at the heart of the Wolverine FRAM LaunchPad uses up to 250x less power than flash based MCUs at low speeds in addition to many other cool benefits.
Be sure to keep an eye out for the new version of Energia, it should be arriving sometime next week. Now is a better time than ever to try out the Tiva C or the MSP430 MCUs!
For the longest time, hardware tinkerers have only been able to play around with two types of memory. RAM, including Static RAM and Dynamic RAM, can be exceedingly fast but is volatile and loses its data when power is removed. Non-volatile memory such as EPROMS, EEPROMS, and Flash memory retains its state after power is removed, but these formats are somewhat slower.
There have always been competing technologies that sought to combine the best traits of these types of memory, but not often have they been available to hobbyists. [Majenko] got his hands on a few MRAM chips – Magneto-Resistive RAM – and decided to see what they could do.
Magneto-Resistive RAM uses tiny pairs of magnetic plates to read and write 1s and 0s. [Majenko] received a sample of four MRAM chips with an SPI bus (it might be this chip, 4 Megabits for $20, although smaller capacity chips are available for about $6). After wiring these chips up on a home-made breakout board, [Majenko] had 16 Megabits of non-volatile memory that was able to run at 40 MHz.
The result was exactly what the datasheet said: very fast write and read times, with the ability to remove power. Unlike EEPROMS that can be destroyed by repeated reading and writing, MRAM has an unlimited number of write cycles.
While MRAM may be a very young technology right now, it’s a wonderful portent of things to come. In 20 (or 30, or 40) years, it’s doubtful any computer from the largest server to the smallest microcontroller will have the artificial separation between disk space and memory. The fact that any hardware hacker is able to play around with this technology today is somewhat amazing, and we look forward to more builds using MRAM in the future.
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