Slight efactor of st7789 driver, and addition of the flip function

drivers/st7789/st7789.cpp

@@ -7,6 +7,7 @@
 #include "hardware/pwm.h"
 
 namespace pimoroni {
+  char madctl[2];
 
   void ST7789::init(bool auto_init_sequence) {
     // configure spi interface and pins
@@ -50,16 +51,17 @@ namespace pimoroni {
       sleep_ms(150);
 
       if(width == 240 && height == 240) {
-        command(reg::MADCTL,    1, "\x04");  // row/column addressing order - rgb pixel order
-        command(reg::TEON,      1, "\x00");  // enable frame sync signal if used
-        command(reg::COLMOD,    1, "\x05");  // 16 bits per pixel
+        madctl = 0x04;
       }
 
       if(width == 240 && height == 135) {
-        command(reg::MADCTL,    1, "\x70");
-        command(reg::COLMOD,    1, "\x05");
+        madctl = 0x70;
       }
       
+      command(reg::MADCTL,    1, madctl);  // row/column addressing order - rgb pixel order
+      command(reg::TEON,      1, "\x00");  // enable frame sync signal if used
+      command(reg::COLMOD,    1, "\x05");  // 16 bits per pixel
+
       command(reg::INVON);   // set inversion mode
       command(reg::SLPOUT);  // leave sleep mode
       command(reg::DISPON);  // turn display on
@@ -147,4 +149,9 @@ namespace pimoroni {
   void ST7789::vsync_callback(gpio_irq_callback_t callback) {
     gpio_set_irq_enabled_with_callback(vsync, GPIO_IRQ_EDGE_RISE, true, callback);
   }
+
+  void ST7789::flip(){
+    madctl[0] ^= 0xC0;
+    command(reg::MADCTL,    1, madctl);
+  }
 }

drivers/st7789/st7789.hpp

@@ -47,6 +47,7 @@ namespace pimoroni {
     void vsync_callback(gpio_irq_callback_t callback);
     void update(bool dont_block = false);
     void set_backlight(uint8_t brightness);
+    void flip();
 
     enum reg {
       SWRESET   = 0x01,

libraries/pico_display/pico_display.cpp

@@ -79,4 +79,7 @@ namespace pimoroni {
     return !gpio_get(button);
   }
 
+  void flip() {
+    screen.flip();
+  }
 }

libraries/pico_display/pico_display.hpp

@@ -26,6 +26,7 @@ namespace pimoroni {
     void set_backlight(uint8_t brightness);
     void set_led(uint8_t r, uint8_t g, uint8_t b);
     bool is_pressed(uint8_t button);
+    void flip();
   };
 
 }