Joining 5 bit variables and splitting them into 8 bit ones later?

[richard]

you are dealing with a matrix that fills like this



its not a particularly easy format to leverage font images that traverse cells , and you cannot read back the data from the matrix
to make life easy i would make a memory array [frame buffer] mapped to the matrix like this





it's then quite straight forward to overlay a font chr into any location
and then create a simple routine to write the frame buffer to the display
in the bit order the matrix demands