Adafruit have released a new version of the SSD1306 OLED library here:
They have chosen not to implement the SPI speed improvements I posted on their forum here:
http://forums.adafruit.com/viewtopic.php?f=19&t=19079&start=15#p103938
To save arguing with them, I'll just post the relevant changes here.
The diffs for Adafruit_SSD1306.cpp are as follows:
*** Desktop/AdafruitSSD1306/Adafruit_SSD1306.cpp 2012-04-18 14:31:38.000000000 +1000
--- Documents/Arduino/libraries/AdafruitSSD1306/Adafruit_SSD1306.cpp 2012-06-04 13:09:57.000000000 +1000
***************
*** 14,19 ****
--- 14,23 ----
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, check license.txt for more information
All text above, and the splash screen below must be included in any redistribution
+
+ SPI speed-ups by Nick Gammon
+ 4th June 2012
+
*********************************************************************/
#include <avr/pgmspace.h>
***************
*** 21,26 ****
--- 25,31 ----
#include <stdlib.h>
#include <Wire.h>
+ #include <SPI.h>
#include "Adafruit_GFX.h"
#include "Adafruit_SSD1306.h"
***************
*** 155,160 ****
--- 160,167 ----
cspinmask = digitalPinToBitMask(cs);
dcport = portOutputRegister(digitalPinToPort(dc));
dcpinmask = digitalPinToBitMask(dc);
+ SPI.begin ();
+ SPI.setClockDivider (SPI_CLOCK_DIV2);
}
else
{
***************
*** 380,392 ****
inline void Adafruit_SSD1306::fastSPIwrite(uint8_t d) {
! for(uint8_t bit = 0x80; bit; bit >>= 1) {
! *clkport &= ~clkpinmask;
! if(d & bit) *mosiport |= mosipinmask;
! else *mosiport &= ~mosipinmask;
! *clkport |= clkpinmask;
! }
! //*csport |= cspinmask;
}
inline void Adafruit_SSD1306::slowSPIwrite(uint8_t d) {
--- 387,393 ----
inline void Adafruit_SSD1306::fastSPIwrite(uint8_t d) {
! SPI.transfer (d);
}
inline void Adafruit_SSD1306::slowSPIwrite(uint8_t d) {
In plain English ...
Edit the library file Adafruit_SSD1306.cpp. Make the following changes:
-
Add another include:
#include <SPI.h> -
In setup(), add:
SPI.begin ();
SPI.setClockDivider (SPI_CLOCK_DIV2); -
Change the contents of the function fastSPIwrite to read just:
SPI.transfer (d);
Save your changes. That's it!
You also need to add this to the start of your sketch:
#include <SPI.h>
You also need to use different pin-outs to use the hardware SPI. Replace the defines at the top of the sketch with these ones:
#define OLED_DC 8 // pin 9 on CD4050B (output: pin 10)
#define OLED_CS 10 // pin 5 on CD4050B (output: pin 4)
#define OLED_CLK 13 // pin 11 on CD4050B (output: pin 12)
#define OLED_MOSI 11 // pin 14 on CD4050B (output: pin 15)
#define OLED_RESET 7 // pin 3 on CD4050B (output: pin 2)
The wiring now needs to be:
Signal Chip out --> Arduino pin
Reset 3 --> 7 (was 13)
CS 5 --> 10 (was 12)
D/C 9 --> 8 (was 11)
CLK 11 --> 13 (was 10)
DAT/MOSI 14 --> 11 (was 9)
That should compile OK, and run somewhat faster.
The changes use the hardware SPI rather than the the software (bit-banged) SPI that they were using. This restricts you to using the hardware SPI pins, whereas their implementation let you use any pins of your choice. If you want speed, make these changes. If you want flexibility, don't. 
Amended library file attached (keep the other ones as they are). Their license.txt file included in order to comply with the licensing requirements. It hasn't changed.
Adafruit_SSD1306.cpp (15.6 KB)
license.txt (1.46 KB)
