Use GxEPD2/extras/sw_spi to probe controller and switch between legacy

and modern epaper displays.

Author: ksedgwic

seedtool/hardware.h

@@ -3,28 +3,11 @@
 #ifndef HARDWARE_H
 #define HARDWARE_H
 
-#include <GxEPD2_BW.h>
+#include <GxEPD2_GFX.h>
 #include <Keypad.h>
 
-// Around April 2020 Waveshare started shipping a new version of the
-// "Waveshare 200x200, 1.54inch E-Ink display module".  The new
-// versions have "Rev2.1" printed under the title on the circuit side
-// of the display.  This new version requires a different driver
-// module from GxEPD2.
-//
-// If you have an *older* display (doesn't have "Rev2.1") uncomment
-// the following line:
-//
-// #define LEGACY_WAVESHARE
-
-#if !defined(LEGACY_WAVESHARE)
-#define EPD_DRIVER GxEPD2_154_D67
-#else
-#define EPD_DRIVER GxEPD2_154
-#endif
-
 // This is hard to hide/encapsulate.
-extern GxEPD2_BW<EPD_DRIVER, EPD_DRIVER::HEIGHT> g_display;
+extern GxEPD2_GFX *g_display;
 
 void hw_setup();
 void hw_green_led(int value);

seedtool/hardware.ino

@@ -4,6 +4,9 @@
 #undef ESP32
 #define SAMD51	1
 
+#define ENABLE_GxEPD2_GFX 1
+#include <GxEPD2_BW.h>
+
 #include "hardware.h"
 #include "util.h"
 
@@ -64,6 +67,8 @@ extern "C" {
 #define GREEN_LED	4
 #endif
 
+GxEPD2_GFX *g_display;
+
 // Display
 #if defined(ESP32)
 GxEPD2_BW<EPD_DRIVER, EPD_DRIVER::HEIGHT>
@@ -72,11 +77,28 @@ g_display(EPD_DRIVER(/*CS=*/   21,
                      /*RST=*/  16,
                      /*BUSY=*/ 4));
 #elif defined(SAMD51)
-GxEPD2_BW<EPD_DRIVER, EPD_DRIVER::HEIGHT>
-g_display(EPD_DRIVER(/*CS=*/   PIN_A4,
-                     /*DC=*/   PIN_A3,
-                     /*RST=*/  PIN_A2,
-                     /*BUSY=*/ PIN_A1));
+
+// Around April 2020 Waveshare started shipping a new version of the
+// "Waveshare 200x200, 1.54inch E-Ink display module".  The new
+// versions have "Rev2.1" printed under the title on the circuit side
+// of the display.  This new version requires a different driver
+// module from GxEPD2 (GxEPD2_154_D67).
+//
+// We declare and initialize both modules and then probe the
+// controller at runtime to see which is connected.
+//
+GxEPD2_BW<GxEPD2_154, GxEPD2_154::HEIGHT>
+display_legacy(GxEPD2_154(/*CS=*/   PIN_A4,
+                          /*DC=*/   PIN_A3,
+                          /*RST=*/  PIN_A2,
+                          /*BUSY=*/ PIN_A1));
+GxEPD2_BW<GxEPD2_154_D67, GxEPD2_154_D67::HEIGHT>
+display_modern(GxEPD2_154_D67(/*CS=*/   PIN_A4,
+                              /*DC=*/   PIN_A3,
+                              /*RST=*/  PIN_A2,
+                              /*BUSY=*/ PIN_A1));
+#define SW_SCK 24
+#define SW_MOSI 23
 #endif
 
 // Keypad
@@ -101,15 +123,30 @@ Keypad g_keypad = Keypad(makeKeymap(keys_), rowPins_, colPins_, rows_, cols_);
 void hw_setup() {
     pinMode(BLUE_LED, OUTPUT);	// Blue LED
     digitalWrite(BLUE_LED, HIGH);
-    
+
     pinMode(GREEN_LED, OUTPUT);	// Green LED
     digitalWrite(GREEN_LED, LOW);
-    
-    g_display.init(115200);
-    g_display.setRotation(1);
 
     Serial.begin(115200);
-    
+
+    // Initialize both versions of the display instance.
+    display_modern.epd2.init(SW_SCK, SW_MOSI, 115200, true, false);
+    display_modern.init(115200);
+    display_legacy.epd2.init(SW_SCK, SW_MOSI, 115200, true, false);
+    display_legacy.init(115200);
+
+    // Read a byte from the display instance to pick a version.
+    uint8_t read_legacy = display_legacy.epd2._readData();
+    serial_printf("read_legacy: readData=0x%02x\n", read_legacy);
+    g_display = read_legacy
+        ? static_cast<GxEPD2_GFX *>(&display_legacy)
+        : static_cast<GxEPD2_GFX *>(&display_modern);
+
+    // Switch back to HW SPI for performance.
+    g_display->epd2.init(-1, -1, 115200, true, false);
+
+    g_display->setRotation(1);
+
 #if defined(SAMD51)
     trngInit();
 #endif

seedtool/seedtool.ino

@@ -17,7 +17,7 @@ void setup() {
     // monitor launched before the tests run.
     //
     // delay(5000);
-    
+
     ui_reset_into_state(SELF_TEST);
 
     Serial.println("seedtool starting");