SSD1306 OLED (72x40) I2C display from scratch

[richard]

yes , aligning the font data packing with the ssd1306's memory page layout is more efficient usage of the 14 bit width of the flash memory
while it will still need some clever manipulation to unpack it into a 8 bit data stream

[flotulopex]

Okay, found!

[flotulopex]

Here is a simple code to get started with this 72x40 display.

I also include the SSD1306 command and display's datasheets.

Since I use EXCEL to design characters, here's the sheet you may want to have a look at.

And again, lots of thanks to Richard

[richard]

You seem to have the communication to the controller well under control
next step is to try to store a font economically, you have probably discovered a large font on a very resource limited chip
like a 690 stored as a series of code structures like
I2CWrite SDA,SCL,I2CDevice,_
[$40,192,224,240,248,252,126,63,63,63,63,63,63,63,6 3,126,252,248,240,224,192,_
255,255,255,255,128,128,128,128,128,128,128,128,12 8,128,128,128,255,255,255,255,_
255,255,255,255,15,15,15,15,15,15,15,15,15,15,15,1 5,255,255,255,255,_
255,255,255,255,0,0,0,0,0,0,0,0,0,0,0,0,255,255,25 5,255]
will by the time you have 10 digits covered will have blown 75% of the chips flash.
fonts can be stored in much better ways, even expanded out as the are read back

[flotulopex]

fonts can be stored in much better ways

Richard, can you point me the direction to do this?

Should I use some kind of algorithm where repetitive numbers could be stored differently or find a way to make better use of the 14 bits word size of the 16F690?

[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

[flotulopex]

Just for fun, scrolling text example