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by travistrue2008
Mon Sep 17, 2018 2:57 pm
Forum: General programming discussion
Topic: Writing a Basic Desktop Compositor
Replies: 2
Views: 2516

Re: Writing a Basic Desktop Compositor

I wouldn't want to take on a project anywhere near that ambitious by myself. I just want to implement something really simple to understand what's going on. I read through that blog article. It was an interesting read. So, the VC4 drivers are finally open source? Also, is Eric Anholt working on clea...
by travistrue2008
Sun Sep 16, 2018 6:12 pm
Forum: General programming discussion
Topic: Writing a Basic Desktop Compositor
Replies: 2
Views: 2516

Writing a Basic Desktop Compositor

I've been researching X and Wayland recently, and I've been wondering about how I could go about writing my own windows compositor that could possibly implement part of the Wayland spec on the Raspberry Pi. Here's how I thought about going about it: I've had a window manager program that'd run as a ...
by travistrue2008
Sun Apr 15, 2018 7:08 pm
Forum: General programming discussion
Topic: How Much of the Raspbian Stack is Open Source?
Replies: 7
Views: 1682

Re: How Much of the Raspbian Stack is Open Source?

Thanks everyone! I've updated my answer to reflect that the DTBs are open, and specified that it's the GPU's firmware that isn't open-source. That's good to know that everything in Raspbian is open-source. That makes sense that the user-space libraries are merely wrappers to talk to the GPU's firmwa...
by travistrue2008
Sat Apr 14, 2018 7:30 pm
Forum: General programming discussion
Topic: How Much of the Raspbian Stack is Open Source?
Replies: 7
Views: 1682

How Much of the Raspbian Stack is Open Source?

I'm learning more about running bare-metal code, assembly, and the Linux stack (kernel, DTB, kernel modules, GNU environment, etc). I thought that Raspbian would be a good start since I want to learn how to write assembly in ARM. I think it would be a fun project to write a micro-kernel in Linux usi...
by travistrue2008
Wed Feb 14, 2018 11:56 pm
Forum: Raspbian
Topic: Electron on Stretch Lite
Replies: 1
Views: 1272

Electron on Stretch Lite

Has anyone attempted to build and run an Electron app on Raspbian without X11? I saw that there was a feature request on Github to make it run in headless mode, but I'm not sure if that request was fulfilled or abandoned: https://github.com/electron/electron/issues/4888 . Just wondering, but if so, ...
by travistrue2008
Wed Feb 14, 2018 11:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Hardware Interface for LCD
Replies: 8
Views: 1776

Re: Hardware Interface for LCD

Thanks! I'll keep that in mind. 6-bit could be a nice tradeoff. I think an 18-bit DPI config would free up those PWM pins.
by travistrue2008
Wed Feb 14, 2018 1:43 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Hardware Interface for LCD
Replies: 8
Views: 1776

Re: Hardware Interface for LCD

I checked out that display, and it looks great! I looked at the specs, but it didn't specify if it was a 16-bit display or a 24-bit one. If it is a 16-bit display, then it sounds like I have two options (with trade-offs): 1) Buy a 24-bit display that's cheaper, but I have to hook it up to 20 GPIOs, ...
by travistrue2008
Tue Feb 13, 2018 5:25 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Hardware Interface for LCD
Replies: 8
Views: 1776

Re: Hardware Interface for LCD

Nice! The shipping price seems outrageous, but I always contact the sellers directly to get a direct quote on pricing. Information such as unit price and MOQ in the product search results page sometimes don't match up with the product description page in Alibaba for some reason... I checked out the ...
by travistrue2008
Tue Feb 13, 2018 1:10 pm
Forum: Teaching and learning resources
Topic: Build My Own Embedded System
Replies: 13
Views: 5942

Re: Build My Own Embedded System

It sounds like I'm out of luck when it comes to working directly with SoCs for the time being. It's ok though. I need to get better at a few things. I could be getting better at circuits, I could be learning more about writing device drivers, and I could be learning more about the Linux stack in gen...
by travistrue2008
Tue Feb 13, 2018 12:27 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Hardware Interface for LCD
Replies: 8
Views: 1776

Hardware Interface for LCD

I found this LCD on Alibaba: https://wholesaler.alibaba.com/product-detail/3-5-inch-tft-lcd-display_1991845761.html I'd like to hook it up to a Pi Zero. The LCD comes with a ribbon cable coming from its driver board as normal, but since the Pi Zero lacks a DSI port, I'll have to solder some jumper w...
by travistrue2008
Mon Feb 12, 2018 12:12 pm
Forum: Teaching and learning resources
Topic: Build My Own Embedded System
Replies: 13
Views: 5942

Re: Build My Own Embedded System

I know I'm beating a dead horse at this point, but I had one last question: would a laser cutter be decent-enough for prototyping my PCBs in-house in the beginning to mount an SoC to it? Here's a Hack a Day article I found where a cheap (<$200), DIY laser cutter from Banggood was able to etch circui...
by travistrue2008
Sun Feb 11, 2018 12:13 pm
Forum: Teaching and learning resources
Topic: Build My Own Embedded System
Replies: 13
Views: 5942

Re: Build My Own Embedded System

Mainly on the job I would say, though not necessarily large companies. People have or acquire an interest in electronics or software engineering, learn theory and skills at college, join companies where they gain the experience in actually doing it, often as part of a team which provides mentoring ...
by travistrue2008
Sat Feb 10, 2018 11:50 am
Forum: Teaching and learning resources
Topic: Build My Own Embedded System
Replies: 13
Views: 5942

Re: Build My Own Embedded System

It is not feasible to buy the SoC. Though the Compute Module overcomes this issue: www.raspberrypi.org/products/ I want to learn how to design and build the embedded hardware, and build my own software stack. I think a custom PCB is an option from the licensed contractors, Element14/RS. Start with ...
by travistrue2008
Fri Feb 09, 2018 11:39 pm
Forum: Teaching and learning resources
Topic: Build My Own Embedded System
Replies: 13
Views: 5942

Build My Own Embedded System

Ever since I was a kid, I always wanted to develop my own video game console. I started using the Pi Zero W as my development board, which is great for developing software apps, learning more about low-level Linux APIs, learning how to develop my own Linux OS stack (I bought a book on the Yocto Proj...
by travistrue2008
Wed Jan 31, 2018 8:18 pm
Forum: C/C++
Topic: Software vs Hardware SPI
Replies: 2
Views: 2179

Re: Software vs Hardware SPI

That's good to know. I only need to read 13 bits of data 100 times a second. I wasn't aware of the SPI driver in the Linux kernel, but I did know about the GPIO driver. I was going off of the gamecon source code, which works off of direct register access to the GPIO.
by travistrue2008
Thu Jan 25, 2018 10:13 pm
Forum: C/C++
Topic: Software vs Hardware SPI
Replies: 2
Views: 2179

Software vs Hardware SPI

I'm writing a device driver based off of the GPIO gamecon driver code. It uses direct registers to interface with the GPIO, and implements SPI in software. I'm going this route because I won't have physical access to all of the pins I need on the board due to the cramped enclosure the Pi has to go i...
by travistrue2008
Wed Jan 24, 2018 6:44 pm
Forum: General discussion
Topic: Powering Pi Zero W OTG
Replies: 5
Views: 1095

Re: Powering Pi Zero W OTG

Ok, that's really good to know. I was worried about connecting the PowerBoost 1000C to the dedicated power port, and then plugging the Pi Zero W into a USB port because it's rare to find one that's not high-powered these days. I'm still new to how circuits work, so I was worried that the PowerBoost ...
by travistrue2008
Tue Jan 23, 2018 7:13 pm
Forum: General discussion
Topic: Powering Pi Zero W OTG
Replies: 5
Views: 1095

Re: Powering Pi Zero W OTG

I'd be using a 2000mAh LiPo battery. Safety has been a major concern, but I've talked it over on the Adafruit forums and also met up with a battery consultant. Fortunately, it looks like the PowerBoost 1000C handles these safety concerns. It's just a matter of making sure I get batteries that have c...
by travistrue2008
Mon Jan 22, 2018 10:20 pm
Forum: General discussion
Topic: Powering Pi Zero W OTG
Replies: 5
Views: 1095

Powering Pi Zero W OTG

I want to develop a battery-powered device out of the Pi Zero W that's also used as a USB gadget in OTG mode. This will allow the user to plug it into a computer's USB port, and use the desktop support software I'm writing to do things such as configuring wifi, transfer files over USB, etc. Then I l...
by travistrue2008
Thu Oct 05, 2017 10:23 pm
Forum: OpenGLES
Topic: Stream OpenGLES to Chromecast
Replies: 0
Views: 1290

Stream OpenGLES to Chromecast

I'm writing an OpenGL ES 2.0 application on my Pi Zero W, and I'd like to stream audio and video to my TV via wifi when not plugged into HDMI, possibly at a lower audio bitrate and video resolution. Right now, I'm considering using a Chromecast to act as the receiver device. I'm using the hello_tria...

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