pull out the framebuffer writing code

Author: ladyada

src/Adafruit_EPD.cpp

@@ -281,6 +281,46 @@ void Adafruit_EPD::drawPixel(int16_t x, int16_t y, uint16_t color) {
   }
 }
 
+void Adafruit_EPD::writeRAMFramebufferToEPD(uint8_t *buffer, uint32_t buffer_size, 
+                                            uint8_t EPDlocation) {
+  // write image
+  writeRAMCommand(EPDlocation);
+  dcHigh();
+  for (uint16_t i = 0; i < buffer1_size; i++) {
+    SPItransfer(buffer[i]);
+  }
+  csHigh();
+  return;
+}
+
+void Adafruit_EPD::writeSRAMFramebufferToEPD(uint16_t SRAM_buffer_addr, uint32_t buffer_size, 
+                                             uint8_t EPDlocation) {
+  uint8_t c;
+
+  // use SRAM
+  sram.csLow();
+  // send read command
+  SPItransfer(MCPSRAM_READ);
+  // send address
+  SPItransfer(SRAM_buffer_addr >> 8);
+  SPItransfer(SRAM_buffer_addr & 0xFF);
+  
+  // first data byte from SRAM will be transfered in at the same time
+  // as the EPD command is transferred out
+  c = writeRAMCommand(EPDlocation);
+  
+  dcHigh();
+  for (uint16_t i = 0; i < buffer_size; i++) {
+    c = SPItransfer(c);
+    // Serial.print("0x"); Serial.print((byte)c, HEX); Serial.print(", ");
+    // if (i % 32 == 31) Serial.println();
+  }
+  csHigh();
+  sram.csHigh();
+}
+
+
+
 /**************************************************************************/
 /*!
     @brief Transfer the data stored in the buffer(s) to the display
@@ -303,72 +343,23 @@ void Adafruit_EPD::display(bool sleep) {
   setRAMAddress(0, 0);
 
   if (use_sram) {
-    sram.csLow();
-    // send read command
-    SPItransfer(MCPSRAM_READ);
-    // send address
-    SPItransfer(buffer1_addr >> 8);
-    SPItransfer(buffer1_addr & 0xFF);
-
-    // first data byte from SRAM will be transfered in at the same time
-    // as the EPD command is transferred out
-    c = writeRAMCommand(0);
-
-    dcHigh();
-    for (uint16_t i = 0; i < buffer1_size; i++) {
-      c = SPItransfer(c);
-      // Serial.print("0x"); Serial.print((byte)c, HEX); Serial.print(", ");
-      // if (i % 32 == 31) Serial.println();
-    }
-    csHigh();
-    sram.csHigh();
+    writeSRAMFramebufferToEPD(buffer1_addr, buffer1_size, 0);
   } else {
-    // write image
-    writeRAMCommand(0);
-    dcHigh();
-    for (uint16_t i = 0; i < buffer1_size; i++) {
-      SPItransfer(buffer1[i]);
-    }
-    csHigh();
-  }
-
-  if (buffer2_size == 0) {
-    update();
-    return;
+    writeRAMFramebufferToEPD(buffer1, buffer1_size, 0);
   }
 
-  // oh there's another buffer eh?
-  delay(2);
-
-  // Set X & Y ram counters
-  setRAMAddress(0, 0);
-
-  if (use_sram) {
-    sram.csLow();
-    // send read command
-    SPItransfer(MCPSRAM_READ);
-    // send address
-    SPItransfer(buffer2_addr >> 8);
-    SPItransfer(buffer2_addr & 0xFF);
-
-    // first data byte from SRAM will be transfered in at the same time
-    // as the EPD command is transferred out
-    c = writeRAMCommand(1);
-
-    dcHigh();
-    for (uint16_t i = 0; i < buffer2_size; i++) {
-      c = SPItransfer(c);
-    }
-    csHigh();
-    sram.csHigh();
-  } else {
-    writeRAMCommand(1);
-    dcHigh();
-
-    for (uint16_t i = 0; i < buffer2_size; i++) {
-      SPItransfer(buffer2[i]);
+  if (buffer2_size != 0) {
+    // oh there's another buffer eh?
+    delay(2);
+    
+    // Set X & Y ram counters
+    setRAMAddress(0, 0);
+    
+    if (use_sram) {
+      writeSRAMFramebufferToEPD(buffer2_addr, buffer2_size, 1);
+    } else {
+      writeRAMFramebufferToEPD(buffer2, buffer2_size, 1);
     }
-    csHigh();
   }
 
 #ifdef EPD_DEBUG

src/Adafruit_EPD.h

@@ -73,6 +73,11 @@ class Adafruit_EPD : public Adafruit_GFX {
   void display(bool sleep = false);
 
 protected:
+  void writeRAMFramebufferToEPD(uint8_t *buffer,
+                             uint32_t buffer_size, uint8_t EPDlocation);
+  void writeSRAMFramebufferToEPD(uint16_t SRAM_buffer_addr, 
+                             uint32_t buffer_size, uint8_t EPDlocation);
+
   /**************************************************************************/
   /*!
     @brief Send the specific command to start writing to EPD display RAM