Hand coded,yes! This was the really work that I did in my first single board computer that at 1979, a NEC uPC8080A CPU was used with a very little size of monitor for me to input program,data, test and run!!! I forgot the ram size, it seems only got 512 bytes or even less!! There was a keyboard that with less than 20keys on the motherboard, a 6 digs 7 segments LED display onboard, a RESET sw, and some pre-drilled hole area on the PBC...I need to do everything with that SBC without the help of the PC because the computer at that time such as the TRS-80, the PET, the APPLE ][ were very very expensive, so the SBC was the only things that I could use. Therefore programming at that time was really a tough and difficult work. But it is not bad because you will treat it series if it is difficult! I remembered at that time I took out my project design book my logbook together with a protable cassette player everytime when I took out my 8080A SBC. Moreover the price of the hardware was very expensive at that time, say the 74LS245 was HK$20 and a 2114 RAM chip (1024*4) was HK$100 !!! Therefore I did very little hardware work in my first computer. So it is really lucky today to do MCU and digital hardware projects....
Back to your question, I suggest you to go to lib to find some books on real time programming, structure programming and program develoment skill. You need to spend some time to read, digest and apply. I also suggest you to get some background knowedge on control theory, what is stabiltiy and how to achive it, what kinds of controller in the plant, how to achive that, what are the algorithms.....etc. if you really want to dig deep in the robotic field, then you are not in programming field but in engineering field. So Maths skill is rather important although it is not fun (at least for me). Try to reserve some time in your everyday life to look at the maths! Anyway Maths is not difficult if you think it is not difficult. Try to tell yourself those are not difficult and you can solve it, overcome it... If you encounter a difficult maths problem and get stuck there, get fear of it and not try to find methods to solve, you will get stuck forever. This was my experience when I first faced the Engineering Maths in undergrad year 1 study. I was not good at maths but too bad I need maths in my study, so I spent days, weeks, months in the lib with my Kreyszig book, read the book, tried the problems, asked my tutor.... Finally I got grade 'A' in my Adv Engg maths subject that year. About Kreyszig, it is rather a good maths book for engg students, I spent lots of hours on it. You can have a look on it if you want to take engg stream in your undergrad study in later years, the name of the book is Advanced Engineering Mathematics, Erwin Kreyszig. I still get the Seventh Edition at hand that bought at 1995 or somethings, I bought the early edition before but that book was damaged due to my everyday using... That book is really thick, my edition got over 1300 pages!!!!
Talk too much on maths! Well hope every success on your project and your study..
Best 73 from Li.