SSD1306 OLED (72x40) I2C display from scratch

[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

[richard]

i'm not seeing a font , i had a look at a 40x18 font this morning with my new 72x40 that just arrived
encoded this way seems the best compromise for easy of unpacking into a 18 x 5 byte stream to send to display










i dont like most of you inital sfr settings
i would replace the entire section with
OSCCON = $70 ;% 01110000 'Internal RC set to 8MHZ


for these reasons
OPTION_REG = % 10000000 'PORT A&B Pull-Ups disabled (see WPUA & WPUB)
Pull-Ups are set that way by default anyway . that does other things to that may later prove to be incorrect Like set int edge to falling, reassign and alter the prescaler, change timer 0 clock source

OSCCON = % 11100000 'Internal RC set to 8MHZ
no 'OSCCON = % 01110000 for 8mhz you have set it for 4 mhz


ANSEL = % 00010100 'Select analog inputs Channels 0 to 7 (AN2 + AN4 selected)
ok but you then go on to make those pins be digital outputs , not recommended except for smoke generation if used as analog inputs


ADCON0 = % 10000000 'A/D Module (Bit5:2 select channels 0:11)
ADCON1 = % 00000000 'A/D control register
why ? makes no sense adc is off by default


CM1CON0 = % 00000000 'Comparator1 Module is OFF
CM2CON0 = % 00000000 'Comparator2 Module is OFF
why ? Comparator 1 and 2 Modules are OFF by default


INTCON = % 00000000 'INTerrupts CONtrol (TMR0 OFF)
why serves no purpose ints are off by default


TRISA = % 00000000 'Set Input/Output (0 to 5)
bad call when an2
TRISB = % 00000000 'Set Input/Output (4 to 7)
bad call when 4,6 used for i2c
TRISC = % 00000000 'Set Input/Output (0 to 7)
bad call when an4


why ? i2c pins can left as be inputs
when breadboarding leave unused pins as inputs. fine set them as low outputs for the "production" version if a few microwatts of power dissipation makes a difference



PORTB = % 00000000 'Ports High/Low (4 to 7)
why ? i2c pins being set low is not useful