As you may have noticed. It has been a while since my last post. I have thought about starting up again many times sine then. Last week I actually did it.

When I stopped I was still in the process of learning more assembly. Though I understand the concept of setting values in registers, more advanced concepts still elude me.

One of those concepts is variables.

in C I would just provide a type, a name, and default value like so.

int pin3 = 3;

In Assembly this is very different. I read about the various sections available and I came across the .bss and .data sections.

Starting off with .bss which is defined as an unitialized section. Usually for uninitialized data. It is declared as follows.

.bss name [,size in bytes]

The idea now is that servo settings can be configured and stored to persistent flash memory in the .data segment.

From there the initial settings can be loaded into the uninitialized .bss section for variable use.

For each servo I plan to define a .bss section as follows.

.bss	servo1,3

In it I create a label servo1 and reserve 3 bytes of memory for it. Why 3, because initially I thought it could hold the desired position, the current position and the number of steps left to get to the desired position. If I ever get this working it will probably need some more bytes of data. The idea of steps cam from another blog, see l’Hexapod. It is an older and seemingly inactive blog, but it holds a lot of information and insights of a similar project.

Next up… learning to work with the variables. I still need to figure out easy ways to address the other bytes in the defined space. The label seems to only point to the first one.