Linux Graphics Programming

September 1, 2017 by 24 Comments

There was a time when embedded system developers didn’t need to worry about graphics. When you have a PIC processor and two-line LCD, there isn’t much to learn. But if you are deploying Linux-based systems today, graphics are a real possibility. There are many options for doing Linux graphics including Wayland, X11, and frame buffers. Confused? This tutorial can help. The sections on Wayland and Mir are under construction, but that’s probably not what you are going to be using on a typical hacker project for the foreseeable future, anyway.

Of course, even inside those broad categories, you have multiple choices. If you are doing X11, for example, you can go low-level or pick any of a number of high-level libraries.

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Microchip’s PIC32MZ DA — The Microcontroller With A GPU

May 30, 2017 by 63 Comments

When it comes to displays, there is a gap between a traditional microcontroller and a Linux system-on-a-chip (SoC). The SoC that lives in a smartphone will always have enough RAM for a framebuffer and usually has a few pins dedicated to an LCD interface. Today, Microchip has announced a microcontroller that blurs the lines between what can be done with an SoC and what can be done with a microcontroller. The PIC32MZ ‘DA’ family of microcontrollers is designed for graphics applications and comes with a boatload of RAM and a dedicated GPU.

The key feature for this chip is a boatload of RAM for a framebuffer and a 2D GPU. The PIC32MZ DA family includes packages with 32 MB of integrated DRAM designed to be used as framebuffers. Support for 24-bit color on SXGA (1280 x 1024) panels is included. There’s also a 2D GPU in there with support for sprites, blitting, alpha blending, line drawing, and filling rectangles. No, it can’t play Crysis — just to get that meme out of the way — but it is an excellent platform for GUIs.

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Manual LCD Makes Information Display Tedious, Educational

April 28, 2017 by 28 Comments

The HD44780 is one of the first chips we learned about as a kid, and chances are good you’ve used one in your project at some point, and almost certain that you’ve interacted with one in your life. The character LCD is ubiquitous, easy to interface, and very robust. They come in sizes from 8 x 1 to 20 x 4 and even larger, but they almost all have the same pinout, and there are libraries in many embedded environments for interacting with them. [The 8-Bit Guy] decided to interface with one using just switches and a button, (YouTube, embedded) with the intent of illustrating exactly how to use them, and how easy they are.

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Upgrade The Graphics On A Sega Game Gear To Mental

March 15, 2016 by 23 Comments

[Nino K] built a portable game player for text adventures. He decided he had spent enough time with the ATmega328 kit from NerdKits to build a more advanced project.

To start with, he built a prototype PCB and tested out the concept. It worked so he began on the real thing. He tore out the guts from a broken Game Gear, saving some parts like those responsible for supplying power. Impressively, he etched his own replacement boards for the Game Gear’s control pads; surprising himself at how simple it ended up being. He fit a 16×4 LCD into the space previously occupied by the Game Gear’s screen.

The program itself is a simple text adventure of his own creation. He even added little 8-bit sprites. The story is classic, a princess has gotten herself in some trouble and a brave hero has been coerced into saving her. Last, he added some music and sound effects from Zelda with a piezo buzzer.

This project is guaranteed to disappoint a visiting younger cousin or relative, but we like to think of that as a feature and not a bug. Great work!

Better 3D Graphics On The Arduino

January 2, 2016 by 20 Comments

There are cheap LCDs available from China, and when plugged into an Arduino, these displays serve as useful interfaces or even shinier baubles for your latest project. [Michael] picked up a few of these displays in the hope of putting a few animated .GIFs on them. This is an impossible task with an ATMega microcontroller – the Arduino does not have the RAM or the processing power to play full-screen animations. It is possible to display 3D vector graphics, with an updated graphics library [Michael] wrote.

The display in question uses the ILI9341 LCD driver, found in the Adafruit library, and an optimized 3D graphics driver. Both of these drivers have noticeable flicker when the animation updates, caused by the delay between erasing a previous frame and when a new frame is drawn.

With 16-bit color and a resolution of 320×240 pixels, there simply isn’t enough memory or the processing power on an ATMega microcontroller to render anything in the time it takes to display a single frame. There isn’t enough memory to render off-screen, either. To solve this problem, [Michael] built his render library to only render pixels that are different from the previous frame.

Rendering in 3D presents its own problems, with convex surfaces that can overlap themselves. To fix this, [Michael]’s library renders objects from front to back – if the pixel doesn’t change, it doesn’t need to be rendered. This automatically handles occlusions.

In a demo application, [Michael]’s LCD and Arduino can display the Stanford bunny, a low-poly 3D face, and geometric object. It’s not a video game yet, but [Michael] thinks he can port the classic game Spectre to this platform and have it run at a decent frame rate.

Video of the demo below.

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Hackaday Prize Entry: HOMER, A 2D GPU For Microcontrollers

June 19, 2015 by 37 Comments

Just about the hardest thing you’ll ever do with a microcontroller is video. The timing must be precise, and even low-resolution video requires relatively large amounts of memory, something microcontrollers don’t generally have a lot of. HDMI? That’s getting into microcontroller wizard territory.

Despite these limitations, [monnoliv] is working on a GPU for microcontrollers. It outputs 1280×720 over HDMI, has a 24 bit palette, and 2D hardware acceleration.

It’s a very interesting project; usually, if you want graphics and a display in a project, you’re looking at a Linux system, and all the binary blobs and closed source drivers that come with that. [monnoliv]’s HOMER video card doesn’t need Linux, and it doesn’t need a very high-powered microcontroller. It’s just a simple SPI device with a bunch of memory and an FPGA that turns the most minimal microcontroller into a machine that can output full HD graphics.

This isn’t the only open source graphics card for microcontrollers in the Hackaday Prize; just a few days ago, we saw VGAtonic, another SPI-controlled video card for microcontrollers, this time outputting VGA instead of HDMI. Both are excellent projects, and if either makes it into production, they’ll both be cheap: under $100 for both of them. Just the thing if you want to play around with high-resolution video without resorting to Linux.

The 2015 Hackaday Prize is sponsored by:

Hackaday Prize Entry: An Open Source Graphics Card

June 15, 2015 by 22 Comments

For last year’s Hackaday Prize, [PK] tried to build a video card for microcontrollers and headless Linux systems. It was only 640×480 resolution VGA, but the entire project was designed around a CPLD communicating with a microcontroller over SPI. This prize entry was, by [PK]’s own admission, a failure. It was late, but now he’s had an entire year to perfect his design. That means he can enter version two of his VGATonic in The Hackaday Prize.

The VGATonic version 2 uses a Xilinx XC95144XL CPLD for the VGA timing, and an ATTiny 2313a to read the SPI bus. Video memory is four megabits of static RAM. That’ls pretty much all you need for the most basic VGA graphics card, and all of this is packed onto a 3×3 inch PCB.

You can do a lot with 640×480 8-bit graphics running at 25FPS. In the video below, [PK] has a ‘hello world’ of sorts, Doom, running on a Raspberry Pi 2 with his SPI graphics card. Yes, it’s a graphics card for the Raspberry Pi, and it looks really good.

Further refinements of the design will include some primitive graphics routines. Not OpenGL or anything fancy, just something to reduce the number of writes on the SPI bus. It’s a great project, and perfect if you want to add video out to an Intel Galileo or other microcontroller project. [PK] has a video demo, you can check that out below.

The 2015 Hackaday Prize is sponsored by:

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