Linux Fu: Forward To The Past!

February 19, 2024 by Al Williams 5 Comments

Ok, so the title isn’t as catchy as “Back to the Future,” but my guess is a lot of people who are advanced Linux users have — at least — a slight interest in retrocomputing. You’d like an Altair, but not for $10,000. You can build replicas of varying fidelities, of course. You can also just emulate the machine or a similar CP/M machine in software. There are many 8080 or Z80 emulators out there, ranging from SIMH to MAME. Most of these will run on Linux or — at the least — WINE. However, depending on your goals, you should consider RunCPM. Why? It runs on many platforms, including, of course, Linux and other desktop systems. But it also will work with the Arduino, Teensy, ESP32, or STM32 processors. There is also experimental support for SAM4S and Cyclone II FPGAs.

It’s pretty interesting to have one system that will work across PCs and embedded hardware. What’s more is that, at least on Linux, the file system is directly translated (sort of), so you don’t have to use tricks or special software to transfer files to and from CP/M. It is almost like giving Linux the ability to run CP/M software. You still have to have virtual disks, but they are nothing more than directories with normal files in them.

Goals

Of course, if your goal is to simulate a system and you want to have 180 kB floppies or whatever, then the direct file system isn’t a benefit. But if you want to use CP/M software for education, nostalgia, or cross-development, this is the way to go, in my opinion.

It isn’t just the file system, either. If you need a quick utility inside your bogus CP/M environment, you can write it in Lua, at least on desktop systems. On the Arduino, you can access digital and analog I/O. Theoretically, you could deploy an embedded Altair for some real purpose fairly cheaply. Continue reading “Linux Fu: Forward To The Past!” →

Linux Fu: The Infinite Serial Port

May 3, 2022 by Al Williams 23 Comments

Ok, the title is a bit misleading. Like most things in life, it really isn’t infinite. But I’m going to show you how you can use a very interesting Linux feature to turn one serial port from a microcontroller into a bunch of virtual ports. In theory, you could create over 200 ports, but the reality is you will probably want to stick with fewer.

The feature in question is what’s known as pseudoterminal or sometimes a pty or pts. These special files were made to feed data to programs that expect to accept data from a terminal. The files provide two faces. To the client, it looks like any other terminal device. To the creator, though, it is just another file. What you write to that file goes to the fake terminal and you can read anything that is sent from the program connected to the terminal. You use these all the time, probably, without realizing it since running a shell under X Windows, for example, doesn’t attach to a real terminal, after all.

You could, of course, do the same trick with a composite USB device, assuming you have one. Also assuming you can find a working driver and get it working. However, many microcontrollers have a serial port — even one with a USB converter built-in — but fewer have full-blown USB hardware. Even the ones that do are often at odds with strange drivers on the PC side. Serial ports work and work well even on the simplest microcontrollers.

The Plan

The plan is simple enough. A Linux program listens to a real serial port and watches for special character sequences in the data stream. Those sequences will allow you to switch data so that the data stream will go to a particular terminal. Data coming back from the terminals will go to the real serial port after sending a sequence that identifies its source.

Continue reading “Linux Fu: The Infinite Serial Port” →

Hackaday Podcast 090: DIY Linux SBC, HDMI CEC, Fake Bluepills, And SCARA Arms

October 23, 2020 by Mike Szczys 2 Comments

Hackaday editors Elliot Williams and Mike Szczys chat about our favourite hacks from the past week. We start off with a bit of news of the Bennu asteroid and the new Raspberry Pi Compute Module. We drive ourselves crazy trying to understand how bobbin holders on sewing machines work, all while drooling over the mechanical brilliance of a bobbin-winding build. SCARA is the belt and pulley champion of robot arms and this week’s example cleverly uses redundant bearings for better precision. And we wrap up the show looking in on longform articles about the peppering of microcontrollers found on the Bluepill and wondering what breakthroughs are left to be found for internal combustion.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Continue reading “Hackaday Podcast 090: DIY Linux SBC, HDMI CEC, Fake Bluepills, And SCARA Arms” →

STM32CubeMX Makes Makefiles

July 15, 2017 by Elliot Williams 31 Comments

When hardware manufacturers make GUI code-generation tools, the resulting files often look like a canned-spaghetti truck overturned on the highway — there’s metaphorical overcooked noodles and red sauce all over the place. Sometimes we think they’re doing this willfully to tie you into their IDE. Not so the newest version of ST’s graphical STM32CubeMX, which guides you through a pleasant pin-allocation procedure and then dumps out, as of the latest version, a clean Makefile.

Yes, that’s right. This is a manufacturer software suite that outputs something you can actually use with whatever editor, GUI, compiler, or environment that you wish — even the command line. Before this release, you had to go through a hacky but functional script to get a Makefile out of the CubeMX. Now there’s official support for real hackers. Thanks, ST!

If you’re compiling on your own, you’ll need to update the BINPATH variable to point to your compiler. (We use the excellent GNU ARM Embedded Toolchain ourselves, which is super-easy to install on almost any Linux.) If you want to use STM32CubeMX with the Eclipse IDE, [kali prasad yadav] sent us PDF instructions — it’s not hard.

If you doubt that the availability of a free, open, and non-constraining toolchain can matter for a silicon vendor, we’d point to AVR and the Arduino platform that spun off of their support of GCC. Sure, Atmel still pushes their all-in-one wonder, Atmel Studio, which is better than the Arduino IDE by most any metric. But Studio is closed, and Arduino is open. We’d love to see the number of Studio users compared with Arduino users.

Congratulations to ST for taking a big step in the right, open-toolchain, direction.

New Part Day: STM32F7, An ARM Cortex-M7

June 26, 2015 by Brian Benchoff 62 Comments

It was announced last year, but ST is finally rolling out the STM32F7, the first microcontroller in production that is based on the ARM Cortex-M7.

The previous go-to part from the ST catalog was the STM32F4, an extremely powerful chip based on the ARM Cortex M4 processor. This chip was incredibly powerful in its time, and is still a respectable choice for any application that needs a lot of horsepower, but not a complete Linux system. We’ve seen the ~F4 chip pump out 800×600 VGA, drive a thermal imaging camera, and put OpenCV inside a webcam. Now there’s a new, even more powerful part on the market, and the mind reels thinking what might be possible.

Right now there a few STM32F7 parts out, both with speeds up to 216MHz, Flash between 512k and 1MB, and 320kB of RAM. Peripherals include Ethernet, USB OTG, SPDIF support, and I²S. The most advanced chip in the line includes a TFT LCD controller, and a crypto processor on-chip. All of the chips in the STM32F7 line are pin compatible with the STM32F4 line, with BGA and QFP packages available.

As with the introduction of all of ST’s microcontrollers, they’re rolling out a new Discovery board with this launch. It features Ethernet, a bunch of audio peripherals, USB OTG, apparently an Arduino-style pin layout, and a 4.3 inch, 480×272 pixel LCD with capacitive touch. When this is available through the normal distributors, it will sell for around $50. The chips themselves are already available from some of the usual distributors, for $17 to $20 in quantity one. That’s a chunk of change for a microcontroller, but the possibilities for what this can do are really only limited by an engineer’s imagination.

THP Entry: A Wireless Bootloaders And Linux Build Systems

June 23, 2014 by Brian Benchoff 7 Comments

radio With The Hackaday Prize, you’re not just limited to one entry. Of course it would be better to devote your time and efforts to only one project if you’re competing for a trip to space, but if you’re [Necromant], you might be working on two highly related project that are both good enough for The Hackaday Prize

[Necromant]’s first project is rf24boot, an over-the-air bootloader using the very cheap and very popular NRF24L01 2.4GHz wireless module. There have been many, many projects that add wireless bootloading to microcontrollers using XBees and the NRF24, but [Necromant] is doing something different with this project: he’s building in support for a wide variety of microcontrollers, that include the STM32, MSP430, PIC32, 8051, and of course AVR chips for that ever so popular Arduino compatibility.

The support of multiple microcontroller platforms is a result of [Necromant]’s other entry to The Hackaday Prize, Antares, the Linux kernel-like build system for microcontrollers. The idea behind Antares is to separate the writing of code from microcontrollers away from compiling and burning. Think of it as a giant makefile on steroids that works with everything, that also includes a few libraries for common projects.

Supported platforms for Antares include the popular aforementioned targets, and allow you to use any IDE you could possibly desire. emacs? Sure. Eclipse? Right on. Arduino? You’re a masochist. For a really great overview of Antares you can check out the Readme, or the post we did a year or so ago.

It’s all very cool stuff, and very easy to see the potential of what [Necromant]’s working on. Combining the two together, it’s almost a complete system for developing that Internet of Things we’ve been hearing about – uploading code to simple AVRs for simple sensors, and deploying significantly more complex code for your ARM-powered dishwasher or microwave.

In-depth Comparison At STM32 F3 And F4 Discovery Boards

November 15, 2012 by Mike Szczys 5 Comments

The STM32 F3 and F4 Discovery boards have been around for a while now. We’ve looked at both separately and they’re impressive dev boards for the price. Now can get a closer look at each from this in-depth comparison of the two Cortex-M4 development tools.

To start off, both of the boards have the same size and footprint (there are two dual-row pin headers which break out the connections to the ARM chip). Fundamentally the F3 and F4 chips have a different level of features, but the boards themselves are aimed at different applications as well. The F3 series of microcontrollers looks to be more affordable than the F4, containing less program memory, no Ethernet capability, and only one USB port. But both have hardware floating-point abilities and they’re blazing fast. The boards offer a MEMS accelerometer for prototyping. But the Discovery-F3 also contains a gyroscope while the Discovery-F4 provides audio hardware like a microphone, and DAC.

If you want to use a Linux box to develop with these tools you might find this guide helpful.