How do I declare a variable in inline ARM Assembly?

if you're using inline assembler in a C or C++ program, you should just define the variable in the C part of the code:

   static uint32_t variable = 0x22222222;

For a separate module using the gnu assembler, data and program space get relocated at link time as appropriate for the chip, so you have to explicitly tell the assembler which "section" to put things in using ".data", ".text", or ".section" directives.  It would look something like:

.data

variable: .long 0x22222222   // global variable

.text

myfunc:

   ldr r1, =variable  ;; get addr of variable from pc-relative constant
   ldr r2, [r1]       ;; get the actual value of variable
   str r2, [r1]         ;; store it back.

That syntax may be a little off...
If you have a lot of global variables, you'd probably set up the base address for all of them in some register, and access them with the offset form of ldr.
If the variable is "local", you can put it on the stack and use [sp] as the base register.

if you're using inline assembler in a C or C++ program, you should just define the variable in the C part of the code:

   static uint32_t variable = 0x22222222;

For a separate module using the gnu assembler, data and program space get relocated at link time as appropriate for the chip, so you have to explicitly tell the assembler which "section" to put things in using ".data", ".text", or ".section" directives.  It would look something like:

.data

variable: .long 0x22222222   // global variable

.text

myfunc:

   ldr r1, =variable  ;; get addr of variable from pc-relative constant
   ldr r2, [r1]       ;; get the actual value of variable
   str r2, [r1]         ;; store it back.

That syntax may be a little off...
If you have a lot of global variables, you'd probably set up the base address for all of them in some register, and access them with the offset form of ldr.
If the variable is "local", you can put it on the stack and use [sp] as the base register.