By default, LDR and STR access complete words of memory (four bytes). However, they can be made to access non word wide memory by the use of the 'B' and 'H' suffixes.
Sizes available:
B byte wide access
H half word access (ARM architecture 4 and later)
Stores to memory which have individual byte lane enables will result in only the chosen lane(s) being updated, but for memory regions which don't have individual byte lane enables, the unused top 8 or 16 bits will be set to zero.
Similarly when reading a 32 bit number with the B or H suffix, the remainder of the bits are zero'd for you.
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