Adding i2cWriteMultiple to speed up I2C transfers

Author: PaulZC

keywords.txt

@@ -60,6 +60,9 @@ draw	KEYWORD2
 drawFace	KEYWORD2
 checkComm	KEYWORD2
 
+setI2CTransactionSize	KEYWORD2
+getI2CTransactionSize	KEYWORD2
+
 #######################################
 # Constants (LITERAL1)
 #######################################
@@ -70,5 +73,3 @@ NORM	LITERAL1
 XOR	LITERAL1
 PAGE	LITERAL1
 ALL	LITERAL1
-
-

src/SFE_MicroOLED.cpp

@@ -365,9 +365,18 @@ void MicroOLED::clear(uint8_t mode)
 		{
 			setPageAddress(i);
 			setColumnAddress(0);
-			for (int j = 0; j < 0x80; j++)
+			if (interface == MODE_I2C)
 			{
-				data(0);
+				uint8_t zeros[0x80];
+				memset(zeros, 0, 0x80);
+				i2cWriteMultiple(i2c_address, (uint8_t *)&zeros, 0x80);
+			}
+			else
+			{
+				for (int j = 0; j < 0x80; j++)
+				{
+					data(0);
+				}
 			}
 		}
 	}
@@ -391,9 +400,18 @@ void MicroOLED::clear(uint8_t mode, uint8_t c)
 		{
 			setPageAddress(i);
 			setColumnAddress(0);
-			for (int j = 0; j < 0x80; j++)
+			if (interface == MODE_I2C)
+			{
+				uint8_t zeros[0x80];
+				memset(zeros, c, 0x80);
+				i2cWriteMultiple(i2c_address, (uint8_t *)&zeros, 0x80);
+			}
+			else
 			{
-				data(c);
+				for (int j = 0; j < 0x80; j++)
+				{
+					data(c);
+				}
 			}
 		}
 	}
@@ -438,9 +456,21 @@ void MicroOLED::display(void)
 	{
 		setPageAddress(i);
 		setColumnAddress(0);
-		for (j = 0; j < 0x40; j++)
+		if (interface == MODE_I2C)
 		{
-			data(screenmemory[i * 0x40 + j]);
+			uint8_t store[0x40];
+			for (j = 0; j < 0x40; j++)
+			{
+				store[j] = screenmemory[i * 0x40 + j];
+			}
+			i2cWriteMultiple(i2c_address, (uint8_t *)&store, 0x40);
+		}
+		else
+		{
+			for (j = 0; j < 0x40; j++)
+			{
+				data(screenmemory[i * 0x40 + j]);
+			}
 		}
 	}
 }
@@ -1099,4 +1129,17 @@ void MicroOLED::drawIcon(uint8_t offsetX, uint8_t offsetY, uint8_t iconWidth, ui
 			columnNumber = offsetX;
 		}
 	}
-}
+}
+
+//Sets the global size for I2C transactions
+//Most platforms use 32 bytes (the default) but this allows users to increase the transaction
+//size if the platform supports it
+//Note: If the transaction size is set larger than the platforms buffer size, bad things will happen.
+void MicroOLED::setI2CTransactionSize(uint8_t transactionSize)
+{
+  i2cTransactionSize = transactionSize;
+}
+uint8_t MicroOLED::getI2CTransactionSize(void)
+{
+  return (i2cTransactionSize);
+}

src/SFE_MicroOLED.h

@@ -1,4 +1,4 @@
-/****************************************************************************** 
+/******************************************************************************
 SFE_MicroOLED.h
 Header file for the MicroOLED Arduino Library
 
@@ -21,9 +21,9 @@ Arduino Pro 3.3V
 Micro OLED Breakout v1.0
 
 This code was heavily based around the MicroView library, written by GeekAmmo
-(https://github.com/geekammo/MicroView-Arduino-Library), and released under 
-the terms of the GNU General Public License as published by the Free Software 
-Foundation, either version 3 of the License, or (at your option) any later 
+(https://github.com/geekammo/MicroView-Arduino-Library), and released under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
 version.
 
 This program is distributed in the hope that it will be useful,
@@ -202,6 +202,13 @@ class MicroOLED : public Print
 	void flipVertical(boolean flip);
 	void flipHorizontal(boolean flip);
 
+	//Control the size of the internal I2C transaction amount
+	void setI2CTransactionSize(uint8_t bufferSize);
+	uint8_t getI2CTransactionSize(void);
+
+	//Set the max number of bytes set in a given I2C transaction
+	uint8_t i2cTransactionSize = 32; //Default to ATmega328 limit
+
 private:
 	uint8_t csPin, dcPin, rstPin;
 	uint8_t wrPin, rdPin, dPins[8];
@@ -220,6 +227,7 @@ class MicroOLED : public Print
 	void spiSetup();
 	void i2cSetup();
 	void i2cWrite(byte address, byte control, byte data);
+	boolean i2cWriteMultiple(byte address, uint8_t *dataBytes, size_t numDataBytes);
 	void parallelSetup();
 	void parallelWrite(byte data, byte dc);
 };

src/hardware.cpp

@@ -1,4 +1,4 @@
-/****************************************************************************** 
+/******************************************************************************
 hardware.cpp
 MicroOLED Arduino Library Hardware Interface
 
@@ -20,9 +20,9 @@ Arduino Pro 3.3V
 Micro OLED Breakout v1.0
 
 This code was heavily based around the MicroView library, written by GeekAmmo
-(https://github.com/geekammo/MicroView-Arduino-Library), and released under 
-the terms of the GNU General Public License as published by the Free Software 
-Foundation, either version 3 of the License, or (at your option) any later 
+(https://github.com/geekammo/MicroView-Arduino-Library), and released under
+the terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
 version.
 
 This program is distributed in the hope that it will be useful,
@@ -97,6 +97,48 @@ void MicroOLED::i2cWrite(byte address, byte dc, byte data)
 	Wire.endTransmission();
 }
 
+/** \brief  Write multiple data bytes over I2C
+
+	Write multiple bytes to I2C device _address_.
+	Returns true if all numDataBytes were pushed successfully
+**/
+boolean MicroOLED::i2cWriteMultiple(uint8_t address, uint8_t *dataBytes, size_t numDataBytes)
+{
+  // I2C: split the data up into packets of i2cTransactionSize
+  size_t bytesLeftToWrite = numDataBytes;
+  size_t bytesWrittenTotal = 0;
+
+  while (bytesLeftToWrite > 0)
+  {
+    size_t bytesToWrite; // Limit bytesToWrite to i2cTransactionSize
+    if (bytesLeftToWrite > (i2cTransactionSize - 1))
+      bytesToWrite = i2cTransactionSize - 1;
+    else
+      bytesToWrite = bytesLeftToWrite;
+
+    Wire.beginTransmission(address);
+		Wire.write(I2C_DATA);
+    size_t bytesWritten = Wire.write(dataBytes, bytesToWrite); // Write the bytes
+
+    bytesWrittenTotal += bytesWritten; // Update the totals
+    bytesLeftToWrite -= bytesToWrite;
+    dataBytes += bytesToWrite; // Point to fresh data
+
+    if (bytesLeftToWrite > 0)
+    {
+      if (Wire.endTransmission(false) != 0) //Send a restart command. Do not release bus.
+        return (false);                          //Sensor did not ACK
+    }
+    else
+    {
+      if (Wire.endTransmission() != 0) //We're done. Release bus.
+        return (false);                     //Sensor did not ACK
+    }
+  }
+
+  return (bytesWrittenTotal == numDataBytes);
+}
+
 /** \brief Set up Parallel Interface
 
 	This function initializes all of the pins used in the