SSD1306 OLED (72x40) I2C display from scratch

[richard]

the font is just a simple block of data
this one is for digits 0 to 9 + "." + "%" its 14 bits high and 10 bits wide [to match chip flash]
so total size is 120 words
for convenience lets locate it a the end of flash - 120 words ie. 0xf88
note this is only partially "filled" in and not very carefully at that

asm       ;incomplete and very rough font 14x10
 org 0xf88
 dw    0x1ffc,0x3ffe,0x3006,0x3006,0x3006,0x3006,0x3006,0x3006,0x3ffe,0x1ffc ;"0"
 dw    0,0x300C,0x300E,0x300F,0x3ffF,0x3ffF,0x3ffF,0x3000,0x3000,0
 dw    0x3806,0x3C07,0x3E03,0x3703,0x3383,0x31E3,0x30F3,0x307F,0x303E,0
 dw    0x3018,0x3006,0x3186,0x3186,0x3186,0x3186,0x3186,0x3006,0x3cf8,0x1ffc  ;"3"
 dw    0,0x3ffe,0,0x3ffe,0,0x3ffe,0,0x3ffe,0,0
 dw    0,0x3ffe,0,0x3ffe,0x3ffe,0x3ffe,0,0x3ffe,0,0
 dw    0x3ffe,0x3ffe,0x3ffe,0,0,0,0,0x3ffe,0x3ffe,0x3ffe
 dw    0x3ffe,0x3ffe,0x3ffe,0,0,0x3ffe,0,0x3ffe,0x3ffe,0x3ffe
 dw    0x1ffc,0x3ffe,0x3186,0x3186,0x3186,0x3186,0x3186,0x3186,0x3ffe,0x1ffc  ;"8"
 dw    0,0x3ffe,0x3ffe,0x3ffe,0x3ffe,0x3ffe,0x3ffe,0x3ffe,0x3ffe,0x3ffe
 dw    0,0,0,0xE00,0x1F00,0x1F00,0xE00,0,0,0    ;"."
 dw    0x181f,0xC11,0x611,0x31f,0x1C0,0x60,0x1F38,0x110c,0x1106,0x1F02  ;"%"
endasm

normally i would make the font an include and give it a label rather than manually locate it like this
dt's macro as found in dt-ints is ideal to find and numerate the font address

GetAddress macro Label, Wout
CHK?RP Wout
movlw low Label ; get low byte
movwf Wout
movlw High Label ; get high byte
movwf Wout + 1
endm

when the fonts address is known its simple to use readcode command to retrieve font data