FPGA Emulates NES Cart; Prototype So Cyberpunk

By now, most of us have had some experience getting ROMs from classic video games to run on new hardware. Whether that’s just on a personal computer with the keyboard as a controller, or if it’s a more refined RetrioPie in a custom-built cabinet, it has become relatively mainstream. What isn’t mainstream, however, is building custom hardware that can run classic video games on the original console (translated). The finished project looks amazing, but the prototype blows us away with it’s beauty and complexity.

[phanick]’s project is a cartridge that is able to run games on the Polish Famicon clone called the Pegasus. The games are stored on an SD card but rather than run in an emulator, an FPGA loads the ROMs and presents the data through the normal edge-connector in the cartridge slot of the console. The game is played from the retro hardware itself. It takes a few seconds to load in each ROM, but after that the Pegasus can’t tell any difference between this and an original cartridge.

The original prototype shown here was built back in 2012. Since then it’s been through a few iterations that have reduced the size. PCBs were designed and built in-house, and the latest revision also includes a 3D-printed case that is closer to the size of the original Famicon cartridges.

Even if you don’t have an interest in classic video games or emulation, the video below is worth checking out. (Be sure to turn on the subtitles if you don’t speak Polish.) [phanick] has put in a huge amount of time getting all of the details exactly right, and the level of polish shows in the final product. In fact, we’ve featured him before for building his own Famicom clone.

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Boost Converter Functionality at Rock-Bottom Prices

Linear voltage regulators are pretty easy to throw into a project if something in it needs a specific voltage that’s lower than the supply. If it needs a higher voltage, it’s almost just as easy to grab a boost converter of some sort to satisfy the power requirements. But if you’re on a mission to save some money for a large production run, or you just like the challenge of building something as simply as possible, there are ways of getting voltages greater than the supply voltage without using anything as non-minimalistic as a boost converter. [Josh] shows us exactly how this can be done using a circuit known as a charge pump to drive a blue LED.

One of the cool things about AVR microcontrollers is that they can run easily on a coin cell battery and source enough current to drive LEDs directly from the output pins. Obviously enough, if the LED voltage is greater than the voltage of the power supply, this won’t work. That is, unless you have a spare diode and capacitor around to build a charge pump.

The negative charge pump works by charging up a capacitor that is connected to an AVR pin, with the other side between the LED and a garden-variety diode to ground. That results in a roughly (VCC – 0.7) volt difference across the capacitor’s plates. When the AVR pin goes low, the other side of the capacitor goes negative by this same amount, and this makes the voltage across the LED high enough to light up. Not only is this simpler than a boost converter, but it doesn’t need any bulky inductors to work properly.

Will this work for any load? Am I going to start any fires by overdriving the LED? Luckily, [josh] answers all of these questions and more on the project page, and goes into some detail on the circuit theory as well. Granted, the charge pump doesn’t have the fine control over the power supply that you can get out of a buck or boost converter (or any switch-mode power supply). But it does have good bang-for-the-buck.

Flashing An ARM With No Soldering

[Sami Pietikäinen] was working on an embedded Linux device based on an Atmel SAMA5D3x ARM-A5 processor. Normally, embedded Linux boxes will boot up off of flash memory or an SD card. But if you’re messing around, or just want to sidestep normal operation for any reason, you could conceivably want to bypass the normal boot procedure. Digging around in the chip’s datasheet, there’s a way to enter boot mode by soldering a wire to pull the BMS pin. As [Sami] demonstrates, there’s also a software way in, and it makes use of mmap, a ridiculously powerful Linux function that you should know about.

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Do You Know The CR816?

Hackaday readers (and writers) are an odd bunch. While the rest of the tech press falls over for the newest, shiniest CPU on the market, we’re the type who’s more interested the unexplored dark corners of metaphorical Silicon Alley. So when someone comes to us with a good writeup of a chip that we’d never heard about, we’re all ears.

[Remy]’s writeup of the CoolRISC 816 microcontroller CPU makes it obvious that he shares our taste for the esoteric. It has a 22-bit “RISC” instruction set. It has a dedicated 8-to-16 bit multiplier. Some of the instructions are so un-reduced that [Remy] calls bunk on its RISC claims. All of the operations, including the un-RISC ones, run in a single cycle. And the CoolRISC does this by cheating — the last stages of the pipeline run not on every clock tick, but on the rising and falling flanks of the clock respectively.

Why all these odd bits? They make the job of the assembly programmer, or compiler designer, a lot easier. With all single-cycle instructions, counting cycles is the same as counting lines of code. The not-really-RISC instructions are great for compiling C into. So what happened? [Remy] speculates that the MSP430, another not-really-RISC microcontroller that came out about the same time, ate the CoolRISC’s lunch. The MSP430 is a 16-bit machine, and chances are good that you’ve heard of TI. The same may not be true of Xemics, maker of the CoolRISC.

But still it’s nice to have someone saying the eulogy for this strange little chip. Or maybe the reports of the CR816’s death are premature — it seems to be inside TI’s bq20x80 chip that’s used in a number of battery power monitors. Oh, the irony! Indeed, watch [Charlie Miller] tear into a battery and find a CR816.

Have any of you used a CR816? What’s the strangest microcontroller architecture that you’ve ever seen?

VGA Without A Microcontroller

One of the most challenging projects you could ever do with an 8-bit microcontroller is generating VGA signals. Sending pixels to a screen requires a lot of bandwidth, and despite thousands of hackers working for decades, generating VGA on an 8-bit microcontroller is rarely as good as a low-end video card from twenty years ago.

Instead of futzing around with microcontrollers, [Marcel] had a better idea: why not skip the microcontroller entirely? He’s generating VGA frames from standard logic chips and big ‘ol EEPROMs. It works, and it looks good, too.

VGA signals are just lines and frames, with RGB pixel values stuffed in between horizontal sync pulses, and frames stuffed between vertical sync pulses. If you already know what you want to display, all you have to do is pump the right bits out through a VGA connector fast enough. [Marcel] is doing this by saving images on two parallel EEPROMs, sending the output through a buffer, through a simple resistor DAC, and out through a VGA connector. The timing is handled by a few 74-series four-bit counters, and the clock is a standard 25.175 MHz crystal.

There’s not much to this build, and the entire circuit was assembled on a breadboard. Still, with the clever application of Python to generate the contents of the ROM, [Marcel] was able to build something that displays eight separate images without using a microcontroller.


Microchip Launches New Family Of PICs

Over the last few years, we’ve seen projects and products slowly move from 8-bit microcontrollers to more powerful ARM microcontrollers. The reason for this is simple — if you want to do more stuff, like an Internet-connected toaster, you need more bits, more Flash, and more processing power. This doesn’t mean 8-bit microcontrollers are dead, though. Eight bit micros are still going strong, and this week Microchip announced their latest family of 8-bit microcontrollers.

The PIC16F15386 family of microcontrollers is Microchip’s latest addition to their portfolio of 8-bit chips. This family of microcontrollers is Microchip’s ‘everything and the kitchen sink’ 8-bit offering. Other families of PICs have included features such as a complementary waveform generator, numerically controlled oscillator, a configurable logic controller, power saving functionality and the extreme low power features, but never before in one piece of silicon.

This feature-packed 8-bit includes a few new tricks not seen before in previous Microchip offerings. Of note are power management features (IDLE and DOZE modes), and a Device Information Area on the chip that contains factory-calibrated data (ADC voltage calibration and a fixed voltage reference) and an ID unique to each individual chip.

As you would expect from a new family of PICs, the 16F15386 is compatible with the MPLAB Xpress IDE and the MPLAB Code Configurator, a graphical programming environment. The products in the family range from 8-pin packages (including DIP!) with 3.5kB of program Flash to 48-pin QFPs with 28kB of program Flash. The goal for Microchip is to provide a wide offering, allowing designers to expand their builds without having to change microcontroller families.

All of these chips can be sampled now, although the lower pin count devices won’t be available through normal means until next month.

Does This Demo Remind You of Mario Kart? It Should!

Here’s a slick-looking VGA demo written in assembly by [Yianni Kostaris]; it’s VGA output from an otherwise stock ATmega2560 at 16MHz with no external chips involved. If you’re getting some Super Mario Kart vibes from how it looks, there’s a good reason for that. The demo implements a form of the Super Nintendo’s Mode 7 graphics, which allowed for a background to be efficiently texture-mapped, rotated, and scaled for a 3D effect. It was used in racing games (such as Super Mario Kart) but also in many others. A video of the demo is embedded below.

[Yianni] posted the original demo a year earlier, but just recently added detailed technical information on how it was all accomplished. The AVR outputs VGA signals directly, resulting in 100×120 resolution with 256 colors, zipping along at 60 fps. The AVR itself is not modified or overclocked in any way — it runs at an entirely normal 16MHz and spends 93% of its time handling interrupts. Despite sharing details for how this is done, [Yianni] hasn’t released any code, but told us this demo is an offshoot from another project that is still in progress. It’s worth staying tuned because it’s clear [Yianni] knows his stuff.

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