In the past 20 years I worked on systems as small as 8bit microcontrollers with no Operating System to systems as large as IBM Z-Series Mainframes. I wrote software for small FreeRTOS, Zephyr and RTEMS based controllers with only a few LED’s as “output” to GUI programs for Windows and Linux.
Since low level programming has some special demands on the programming language the main languages I use, and consider myself a professional in, are C, C++, and when it can’t be avoided assembly. Other languages like Python, bash-scripting, lua, cmake, are also part of my daily work.
Due to personal interest and experience there are some areas where I can offer additional knowledge that can speedup things compared to software developers that are new in those areas.
Linux Embedded Distribution Development
For systems that can’t use an average Linux distribution like Debian, Fedora, etc. because of for example storage size restrains I develop highly customizable distributions based on PtxDist or Yocto that can be as small as 8 MByte.
Low Level Driver Development
When there is a need for a small specialized Linux distribution it most of the times means there is some custom hardware in use. For that hardware I can develop low level device drivers for the Linux kernel and bootloaders like U-Boot and Barebox.
RTOS and Baremetal
For systems where a 8 MByte OS is still to large I can offer baremetal or RTEMS, FreeRTOS and Zephyr based solutions on PowerPC, AVR32, and mostly ARM.
Lighting Control
Lighting Control for stage and theater is an rather specialized area with several unique technologies. Having knowledge of technologies like for example DMX, RDM, Art-Net and ACN, makes it a lot easier for me to get up to speed in software development projects that deal with those technologies.
Public Information Systems
Like with Lighting Control systems, Public Information Systems in the public transportation area deal with specialized protocols and demands. Working for clients in doing public transportation information systems and for clients doing public transportation power converters I collected extensive knowledge in that area.
Prettige Kerst, Merry X-Mas, of course in style, by using a Xilinx FPGA to control a cheap 64x32 RGB LED matrix display.
I wrote a small program in VHDL that shift out a image to the RGB module and takes care of everything. After building it with Xilinx Vivado the resulting schematic looks like this;
Of course if this is not an example of how to do things for a real project, first of all the LED module lacks features like PWM control, current correction, over temperature protection, and simply the needed brightness compared to professional displays that are for example produced by my one of my clients.
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After,
Fixing the mainboard Refurbishing the PSU Installing the SCSI2SD Installing the GoTek drive Finally done!
Well almost, because there where some small problems. First of all, and I wonder why I didn’t notice that before, the bottom of the case was badly warped.
So I had to take everything out again and bend the case into a bit more acceptable shape. And of course rebuild the whole thing again. After this “mechanical” problem, it was time to install the software.
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After the SCSI HD conversion from a real HD to a SD-Card, it is time to add a way to easily use floppy images by adding a GoTek floppy emulator.
The GoTek case is a lot smaller than the 3.5" floppy opening, some kind of frame is needed.
Since the previous owner already drilled some holes in the slot plate I used that as a frame for the GoTek. I simply cut out the center and super glued the frame to the GoTek case.
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After fixing the Amiga 2000 motherboard and the refurbishing the PSU I upgraded the HD from a real SCSI-drive to a SD-Card via a SCSI2SD.
Together with my brother in law and his company Art and Tech VoF we created a 3D printed bracket that makes it possible to attach the SCSI2SD onto the Amiga SCSI controller card where the HD used to be. We also created a new slot plate that make it possible to access the SD-card and USB port from the back of the Amiga.
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The MOS Technology 6581/8580 SID (Sound Interface Device) is the almost 40 year old sound chip that was used in the famous Commodore 64. It uses a 5bit address / 8bit data synchronous bus with a chip select, rw, and clock signal. Since the chip uses the 1MHz (well not exactly 1MHz as I’ll explain later) clock signal also to generate all the audio frequencies, so it is important that the clock signal is stable, even though the read/write access would work fine with a unstable clock as long as the signal setup times are correct.
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To understand what this is about you absolutely should watch Dylan Beattie’s brilliant presentation about The Art of Code.
Now you know Rockstar is a computer programming language designed for creating programs that are also hair metal power ballads.
The famous Fizzbuzz program looks like this.
Midnight takes your heart and your soul
While your heart is as high as your soul
Put your heart without your soul into your heart
Give back your heart
Desire is a lovestruck ladykiller
My world is nothing
Fire is ice
Hate is water
Until my world is Desire,
Build my world up
If Midnight taking my world, Fire is nothing and Midnight taking my world, Hate is nothing
Shout "FizzBuzz!
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After fixing the Amiga 2000 motherboard it was time to cleanup the power supply. I preemptively wanted to remove all the electrolytic capacitors so I ordered some new ones.
Since the power supply is just a single sided PCB, getting the old capacitors out and soldering the new capacitors in would be relatively easy. But this model (later versions don’t seem to have it) has a little daughter PCB that kind of block access and itself also had two capacitors on it that I also wanted to replace.
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A while back I bought a non-working Amiga 2000 that, according the seller, only displayed a white screen. In the 80’s and early 90’s I only had an Amiga 500, so I thought it would be fun to now get a working Amiga 2000, and restoring one would be a nice X-mas holiday project.
Dealing with the Amiga Killer One of the main Amiga 2000 killers is the battery, after 30 plus years they tend to leak and in the worst case can corrode away half the PCB.
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How do you mean I can’t do make clean, fix bugs, make all ? When software engineers make hardware things can only go wrong; notice the size of the switch and the footprint on the PCB. But apart from that, pretty fly for a software guy.
The PCB design was done with KiCad on Linux (but it is also available for Windows and MacOS).
