Add ability to reset display without clearing CGRAM or turning display off.

Author: nseidle

library.properties

@@ -1,5 +1,5 @@
 name=SparkFun Qwiic OLED Graphics Library
-version=1.0.3
+version=1.0.4
 author=SparkFun Electronics <[email protected]>
 maintainer=SparkFun Electronics <sparkfun.com>
 sentence=Library for SparkFun SSD1306 based OLED display products.

src/SparkFun_Qwiic_OLED.h

@@ -169,10 +169,11 @@ class QwiicOLEDBaseClass : public Print { // NOTE: implementing Arduino Print
     //
     //  Parameter   Description
     //  ---------   -----------------------------    
-    //  retval      true on success, false on  failure    
+    //  clearDisplay true - clear the internal buffers during reset
+    //  retval      true on success, false on failure    
 
-    bool reset(void){
-        return _device.reset();
+    bool reset(bool clearDisplay){
+        return _device.reset(clearDisplay);
     }
 
     ///////////////////////////////////////////////////////////////////////

src/qwiic_grssd1306.cpp

@@ -264,7 +264,7 @@ bool QwGrSSD1306::init(void)
 //
 // Returns true on success, false on failure
 
-bool QwGrSSD1306::reset(void){
+bool QwGrSSD1306::reset(bool clearDisplay){
 
     // If we are not in an init state, just call init
     if(!_isInit)
@@ -275,11 +275,11 @@ bool QwGrSSD1306::reset(void){
         return false;
 
     // setup oled
-    setup_oled_device();
+    setup_oled_device(clearDisplay);
 
     // Init internal/drawing buffers and device screen buffer
-
-    init_buffers();
+    if(clearDisplay)
+        init_buffers();
 
     return true;
 }
@@ -320,11 +320,12 @@ void QwGrSSD1306::set_contrast(uint8_t contrast){
 // Method sends the init/setup commands to the OLED device, placing 
 // it in a state for use by this driver/library.
 
-void QwGrSSD1306::setup_oled_device(void){
+void QwGrSSD1306::setup_oled_device(bool clearDisplay){
 
     // Start the device setup - sending commands to device. See command defs in header, and
     // device datasheet
-    send_dev_command(kCmdDisplayOff);
+    if(clearDisplay)
+        send_dev_command(kCmdDisplayOff);
 
     send_dev_command(kCmdSetDisplayClockDiv, 0x80);
     send_dev_command(kCmdSetMultiplex, _viewport.height - 1);
@@ -346,8 +347,8 @@ void QwGrSSD1306::setup_oled_device(void){
     send_dev_command(kCmdSetVComDeselect, _initVCOMDeselect);
     send_dev_command(kCmdDeactivateScroll);
 
-    send_dev_command(kCmdDisplayOn);
-
+    if(clearDisplay)
+        send_dev_command(kCmdDisplayOn);
 }
 ////////////////////////////////////////////////////////////////////////////////////
 // set_comm_bus()

src/qwiic_grssd1306.h

@@ -167,7 +167,7 @@ class QwGrSSD1306 : public QwGrBufferDevice {
     // Device setup
     virtual bool init(void);
     bool is_initialized(void) { return _isInit; };
-    bool reset(void);
+    bool reset(bool clearDisplay = true);
 
     // method to set the communication bus this object should use
     void set_comm_bus(QwI2C &theBus, uint8_t id_bus);
@@ -234,7 +234,7 @@ class QwGrSSD1306 : public QwGrBufferDevice {
     void init_buffers(void); // clear graphics and screen buffer
     void clear_screen_buffer(void);
     void resend_graphics(void);
-    void setup_oled_device(void);
+    void setup_oled_device(bool clearDisplay = true);
 
     // device communication methods
     void send_dev_command(uint8_t command);