Writing to LCD from MSP430

There are no 'C' commands other than the commands defined in the C standard.

Contrary to basic, where there is no standard at all and everyone can call his collection of commands 'basic', C is a standardized programming language that offers everything you nee to structurize your program and the data you want to use. And while Basic is most often an interpreter language (tha tmeans, your program is a script that is interpreted at runtime), C is compiled and then executed on processor hardware level. A C-Program by itself can be compiled for every processor where a C compiler exists.

IF it does what you want, however, depends on some other things:

There is a standard library defined that is usually provided for every C compiler and target processos. This library contains some (often but not always heavily optimized) functions. These functions are not more than standard C code itself, as you could write yourself more or less easily, but provide a base of often-required functionality, such as converting a binary value to a text, comparing two strings and such. This library should be available for your compiler too. Note that this library belongs to the compiler (and often, teh source code of the included functions is also available), even if specifically written for the target processor (as the compiler is too).

There might be more than this standard library available for yor compiler/processor combo. Either from the processor manufavturer, or from the OS manufacturer (if you decide to use one) or from other users. Still this is optional and just more 'C' code (or assembly code, as C supports being linked with machine-level assembly code).

The MSP itself is a dumb thing. Powerful, but with no integreted code (other than the bootloader). Everything it shall do must be implemented by your program, either directly through your code or by additinal libraries that _you_ link to your code (as if they were part of your code). Only the standard library is usually handled automatically.

In C, there is another element in addition to your code: header files. The compiler usually compiles each code file (*.c) separately. To tell the compiler, that other code files contain functions you can use, there are header files (*.h*) which contain info about what has been already compiled in the code file they belong to. THis is no automated process, these files need to be written manually. If you have a library (such as the standard lib), it comes with one or more header files which describe the names and parameters of the functions in the code/library they belong to. (Not necessarily all, there might be more in the lib that is used internally only).

These header files can also describe variables or data structures for global use. And here is the processor specific link. There should be a bunch of header files for the MSP where the hardware regiosters of the MSP are defined as global variables. And the values to write there are defined as global usable values (aliases/macros). These header files are included into your current C file by teh #include directive

#include "msp430xW42x.h"

This file may contain all you need or include others depending on your processor, as some things are common across different MSPs, others are device-specific. Look into it and you'll find many definitions which are to be used later in your code. But keep in mind that this is primarily informaiton for the compiler, so it is valid C code, but maybe not too descriptive for humans. It just tells the compiler facts about what is there, not what it is to be used for. But there may be some additional descriptive comments.

If the TI techdocs talk about a register such as UCA0CTL0 (Usci a0 control register 0), then most certainly a global variable of this name has been defined in one of these MSP header files. So the instruction

UCA0CTL0 = 1;

will write the value 1 into the control register. Instead of '1' there usually are aliases available for all the bits you can find in this register.

I don't have the docs of your processor, but if e.g. there is a register in the docs named LCDM0, then the command LCDM0=0xff; will set all LCD segments this register belongs to to 'on'. As far as I can remember, this would be LCD segment 0 and 1 (lower and upper 4 bit of 0xff) for multiplex0-3 (bit0..3 or 4..7 respectively.) LCDM0=0x82 would set segment 1 on for multiplex stage 1 and segment 0 on for multiplex stage 2 only.

You can then go and write a C function that takes a value (0..9) and a position (0..15) and maybe a 'dot' flag, and calculates which bits in the LCDMx registers to set or clear so the number appears at the desired position. To make things easier you can define tables with the corresponding segment patterns etc. You can also write a funtion that rotates the current display or shifts it or whatever you want.

So what does your LCD demo program do? First, it initialized the hardware. This is settign up a timer that will call the interrupt vector in certain intervals. Then the processor ports are set for proper operation (PxSEL selects special hardware funcitonality for the corresponding port pins of thsi port, PxDIR sets the pins for output, default is standard I/O input), then the LCD icontroller is configured and a initial pattern is written into the display .

Next step don in main() is to set the processor asleep until the timer times out and wakes it up again (this wakeup is done in the basic_timer interrupt fiunction. (the #pragma-lien befor it tells the compiler that this function is to be linked to the timer event). Then Main calls the DisplayAccessories-Function whcih simply writes a new predefined pattern into the LCD memory registers, then port pin P1.0 is toggled (I guess there is an LED attached?) before falling asleep again.

Try to figure out why the display shows what it shows when the code writes certain value sinto the LCD memory and you should finally understand how it works.