Dear all,
I have two versions of what I believe to be SSD1306 displays
-
HelTec, CS is already connected to GND, this is the OLD version of the HelTec
http://www.ebay.com/itm/201009010892?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT -
Another brand, CS is brought out as a pin, reason I bought it
http://www.ebay.com/itm/291168368309?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Now both displays work with U8Glib, I used the OLED_Scale example with this constructor:
U8GLIB_SSD1306_128X64 u8g(13, 11, 10, 9, 2); // SW SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9
Display (1) seems to work fine with the AdaFruit libraries for the SSD1306, however display (2) only works partially with this code. I want to understand why (in order to write a few very simple functions for my display).
My code taken from the AdaFruit example:
#include <SPI.h>
#include "ssd1306_1.h"
#include "Arduino.h"
#include "glcdfont.h"
typedef volatile uint8_t PortReg;
typedef uint8_t PortMask;
PortReg *mosiport, *clkport, *csport, *dcport;
PortMask mosipinmask, clkpinmask, cspinmask, dcpinmask;
int8_t vccstate, sid, sclk, dc, rst, cs;
void setup()
{
Serial.begin(9600);
dc = 9;
rst = 2;
cs = 10;
vccstate = SSD1306_SWITCHCAPVCC;
pinMode(dc, OUTPUT);
pinMode(cs, OUTPUT);
pinMode(rst, OUTPUT);
csport = portOutputRegister(digitalPinToPort(cs));
cspinmask = digitalPinToBitMask(cs);
dcport = portOutputRegister(digitalPinToPort(dc));
dcpinmask = digitalPinToBitMask(dc);
SPI.begin ();
SPI.setClockDivider (SPI_CLOCK_DIV2); // 8 MHz
// Setup reset pin direction (used by both SPI and I2C)
digitalWrite(rst, HIGH);
// VDD (3.3V) goes high at start, lets just chill for a ms
delay(1);
// bring reset low
digitalWrite(rst, LOW);
// wait 10ms
delay(10);
// bring out of reset
digitalWrite(rst, HIGH);
// turn on VCC (9V?)
// Init sequence for 128x64 OLED module
ssd1306_command(SSD1306_DISPLAYOFF); // 0xAE
ssd1306_command(SSD1306_SETDISPLAYCLOCKDIV); // 0xD5
ssd1306_command(0x80); // the suggested ratio 0x80
ssd1306_command(SSD1306_SETMULTIPLEX); // 0xA8
ssd1306_command(0x3F);
ssd1306_command(SSD1306_SETDISPLAYOFFSET); // 0xD3
ssd1306_command(0x0); // no offset
ssd1306_command(SSD1306_SETSTARTLINE | 0x0); // line #0
ssd1306_command(SSD1306_CHARGEPUMP); // 0x8D
if (vccstate == SSD1306_EXTERNALVCC)
{ ssd1306_command(0x10); }
else
{ ssd1306_command(0x14); }
ssd1306_command(SSD1306_MEMORYMODE); // 0x20
ssd1306_command(0x00); // 0x0 act like ks0108
ssd1306_command(SSD1306_SEGREMAP | 0x1);
ssd1306_command(SSD1306_COMSCANDEC);
ssd1306_command(SSD1306_SETCOMPINS); // 0xDA
ssd1306_command(0x12);
ssd1306_command(SSD1306_SETCONTRAST); // 0x81
if (vccstate == SSD1306_EXTERNALVCC)
{ ssd1306_command(0x9F); }
else
{ ssd1306_command(0xCF); }
ssd1306_command(SSD1306_SETPRECHARGE); // 0xd9
if (vccstate == SSD1306_EXTERNALVCC)
{ ssd1306_command(0x22); }
else
{ ssd1306_command(0xF1); }
ssd1306_command(SSD1306_SETVCOMDETECT); // 0xDB
ssd1306_command(0x40);
ssd1306_command(SSD1306_DISPLAYALLON_RESUME); // 0xA4
ssd1306_command(SSD1306_NORMALDISPLAY); // 0xA6
ssd1306_command(SSD1306_DISPLAYON);//--turn on oled panel
/* fill screen with alternating black and white pixels */
ssd1306_command(SSD1306_COLUMNADDR);
ssd1306_command(0); // Column start address (0 = reset)
ssd1306_command(127); // Column end address (127 = reset)
ssd1306_command(SSD1306_PAGEADDR);
ssd1306_command(0); // Page start address (0 = reset)
ssd1306_command((SSD1306_LCDHEIGHT == 64) ? 7 : 3); // Page end address
// SPI
*csport |= cspinmask;
*dcport |= dcpinmask;
*csport &= ~cspinmask;
for (uint16_t i=0; i<(SSD1306_LCDWIDTH*SSD1306_LCDHEIGHT/8); i++)
{
(void)SPI.transfer(B10101010);
}
*csport |= cspinmask;
}
void loop()
{
}
void ssd1306_command(uint8_t c)
{
// SPI
//digitalWrite(cs, HIGH);
*csport |= cspinmask;
//digitalWrite(dc, LOW);
*dcport &= ~dcpinmask;
//digitalWrite(cs, LOW);
*csport &= ~cspinmask;
(void)SPI.transfer(c);
//digitalWrite(cs, HIGH);
*csport |= cspinmask;
}
void ssd1306_data(uint8_t c)
{
// SPI
//digitalWrite(cs, HIGH);
*csport |= cspinmask;
//digitalWrite(dc, HIGH);
*dcport |= dcpinmask;
//digitalWrite(cs, LOW);
*csport &= ~cspinmask;
(void)SPI.transfer(c);
//digitalWrite(cs, HIGH);
*csport |= cspinmask;
}
The code is supposed to print alternating black and white lines on the screen. I get the following results:
If I run my own (adafruit-based) code first, I get images (1A) en (2A): a lot of trash on screen (2). Running the U8Glib code yields good results: (1B) and (2B). If I then flash my Arduino to my own code and run it, I get (1C) (good again) and (2C): it seems I can only write to part of the screen. (I ran the tests in the order 1A, 1B, 1C, 2A, 2B, 2C)
Now the U8Glib code is done very nicely, but I find it hard to track what is happening. As far as I can tell it uses the same initialization sequence as AdaFruit (the code says so). Display (2) does work, just not with my code. There must be something I'm missing, but I have no clue. I have worked through the datasheet of the SSD1306, but found no extra clues.
I hope someone (mayhaps even Oliver) can shed some light on this and give me a pointer where to look.
Cheers,
Jack
): yes it is. But it runs to 132 instead of 128 before rolling over, so pixels tend to get displaced after writing an entire row. So better reset this when you select a new page.