MSP430 Development on Linux

For the last few years, I've moved as many of my programming projects as possible from Windows to Linux. This includes PIC32 programming as explained in MIPS Development on Linux. My most recent MSP430 projects like the Electronic Birthday Card, Kitty Salon, and some Christmas tree ornaments for this past Christmas were programmed entirely on Linux. On the other hand, my Tiny Calculator project, which started in 2018, is compiled with IAR Embedded Workbench running on Windows. Since returning to the Tiny Calculator is one of my goals for the coming year, I spent some time improving my MSP430 setup on Linux.

MIPS Development on Linux

Two of the projects from my 2022 project goals use a PIC32 microcontroller. The company that makes them, Microchip, offers an IDE and a compiler which is a port of GCC. The free version of the compiler has some limitations which would make it difficult to finish one of my projects. However, since the PIC32 is a MIPS core, I was able to set up some tools on Linux as an alternative.

The two main limitations of the Microchip compiler are that it doesn't allow GCC's -O3 level optimizations or compile to the MIPS16e instruction set unless you pay for the full version. The loss of MIPS16e is a real bummer since it saves a lot of program memory by using 16-bit instead of 32-bit instructions like ARM's Thumb instruction set. Microchip claims that programs in this format are 40% smaller without losing much performance which would be great for one of my projects. The standard MIPS GCC has none of these limitations, but it also doesn't come with any headers or other files specific to the PIC32. This got me thinking about how I could combine the two tools and use MIPS GCC on Linux to generate part of the program. Running a few tests shows that Microchip's compiler will accept assembly files written for either the 16-bit or 32-bit instruction set, and the linker will accept object files for either instruction set too. This way, all the chip specific parts of the program like initial setup can be compiled with Microchip's compiler while the bulk of the program can be compiled externally with optimizations and linked in later.

Linux for Embedded Development

A little over a year ago, I bought a new Casio FX-9750GIII graphing calculator. It really appealed to me for several reasons so I decided to buy one even though my days of collecting calculators are mostly over. One of the main things I like is that it comes with Python which has become one of my favorite programming languages. Another interesting thing is that the processor speed was doubled to 59MHz over the preceding FX-9750GII making it as fast as the FX-9860GII and the FX-CG50. Amazingly, there is a port of Xcas for it, so you can run the same Computer Algebra System (CAS) used in the HP Prime, TI-89, and TI-Nspire. The styling of this one has changed back to the standard rectangular design which is much better than the awkward and ugly rounded design Casio used for some of the preceding models. All of this is very impressive and it only costs $39! Best of all, it can run programs written in C and assembly like previous Casio models. Other modern calculators like the HP Prime, TI-Nspire, and TI-84+ CE don't allow native code execution which is why I've stayed away from them. The catch with the FX-9750GIII is that the GCC toolchain put together by the community only runs on Linux. It took quite a bit of work getting the toolchain installed on Ubuntu in a virtual machine since I didn't have much experience with Linux. A few months ago, I moved everything over to an old server that someone donated. Below are some things I've learned while doing more and more of my embedded projects on Ubuntu.

Virtual Machine
At first, I installed Ubuntu Server on VirtualBox so I could use the GCC toolchain for the FX-9750GIII. It took quite a while to install and then some more work to get things like networking and a shared folder with the host to work. The GCC toolchain turned out to be very problematic to install which was not entirely due to my lack of experience with Linux. Thankfully, the maintainer of the toolchain put in a lot of work helping me get it working on the Planet Casio forum. One of the first problems was trying to get the scripts working without understanding how the various types of shells work in Linux which is very different from the Windows command prompt I'm used to using. There is a package called GiteaPC that the maintainers put together that is supposed to install everything, but this didn't work for me at first either. Other problems were beyond my control such as not being able to update CMake to the version the toolchain requires. For this, I had to update Ubtuntu from 20.04 LTS to 21.04 which does not have long term support. CMake also had problems finding the PATH variables. Eventually, I did get the toolchain running, though it failed when trying to install it again sometime later since the maintainers had changed the toolchain's structure so it no longer built correctly. In the end, I did get GiteaPC working, again with the help of the maintainers, though I have to say the weeks-long process of just getting to Hello, World was pretty awful. All of this led me to reinstalling Ubuntu several times on VirtualBox.