VIC™ - A compiler for Microchip’s PIC® Microcontrollers

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The Inception of VIC™

VIC™ originated from finding difficulty in writing generic code that would run on any micro-controller of Microchip’s PIC® family that were similar in nature, such as any PIC® of the PIC12, PIC16 family or the PIC18 family.

There were various options such as using C or PICBASIC™ with Microchip’s compilers or using Just Another Language (JAL) which is an interesting high level language that also helps users to program PIC® microcontrollers with ease and provides a variety of libraries.

However, the JAL syntax did not seem interesting since it was based off of Pascal. Their simulator webpage links also did not work. Using Microchip’s PICBASIC™ was equally as cumbersome as using their C compiler, which did not allow for ease of understanding of the code after a period of time. With increasing complexity of code, these options started to seem less and less desirable. Every time a new project was to be done, we ended up having to copy-paste code for various common things and obviously, that led to various unforeseen errors and sometimes having to rewrite everything from scratch every time. We did start to write functions and libraries of our own, but in the end we decided that auto-generation of code was more desirable for long term maintenance of our projects.

This is one of the main reasons of the desire to use a domain specific language such as VIC™ which would make it easy for the developer to write code representing the Do What I Mean (DWIM) philosophy and allowing for code re-use without having to deal with issues arising from copy-pasting code from earlier projects. The other necessity was that if we wanted to swap out one microcontroller for another, we should not have to read the data sheet and make sure that the code would work, or have to make changes to register names for the code to be usable. We just wanted the compiler to do this for us. Hence, today VIC™ does that for you. VIC™ also would then allow for custom optimizations to be made for specific microcontrollers that would not be needed for the generic cases.

Moreover, there was a requirement to write code in such a way such that it would be less procedural and more event or action based, where certain functions would invoke certain actions if needed. This would enable clarity for the programmer and QA tester who would be verifying the code and creating test benches to verify outputs.

Another requirement was to make the code very easy to debug, which is why VIC™ generates valid assembly code which can work in any existing PIC® debugger such as that from Microchip or something open source like Piklab.

We also wanted to have an easy way to generate boiler plate code. In various scenarios, you would want boiler plate code generated and then modified slightly for different applications. This boiler plate code would be generated using pre-processor macros which were quite irritating to use and create, especially if you wanted to use the same boiler plate code for different microcontrollers, you would have to write these macros for each microcontroller. VIC™ would automate this where you would write the boilerplate code once, and the compiler would generate the appropriate code for the microcontroller specified. This would generate assembly to which further modification could take place by the experienced developer for specific cases where assembly programming would be necessary.

VIC™ would also have a way to integrate with existing PIC® simulators like GNU PIC simulator gpsim, and integrates with the GNU PIC assembler gpasm.

In addition to all of this, having to read data sheets for each microcontroller in detail to implement standard features like debouncing inputs, analog to digital conversion (ADC), UART/SPI/I2C serial bus implementation could be completely avoided if VIC™ provided these out of the box.

Last but not the least, VIC™ would have a method to perform formal verification of the code. This would be the killer feature needed for those performing microcontroller programming for devices that are mission critical and need to have a high reliability rating such as in the fields of medicine and aerospace. However, this feature has not been implemented yet.

Development Style

VIC™’s development style is a mixture of procedural and event-based. Certain instructions such as timers, debouncers have event-based actions that get invoked when the conditions are met. This allows for the programmer to implement Perl or Javascript like event callbacks for such tasks.

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Vikas N Kumar (@vikasnkumar) is the author of VIC™. All copyrights belong to the author and Selective Intellect LLC.

VIC™ is licensed under the license terms of Perl.
The development of VIC™ is sponsored by Selective Intellect LLC.

This page was last updated on 2014-10-28 21:27:34 -0400.