Autodetect SSD1306 vs SH1106 OLED type

main/configuration.h

@@ -169,11 +169,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #endif
 
 #define RED_LED 4  // GPIO4 on T-Beam v1.1
-// -----------------------------------------------------------------------------
-// OLED
-// -----------------------------------------------------------------------------
-
-#define SSD1306_ADDRESS 0x3C
 
 // -----------------------------------------------------------------------------
 // GPS

main/main.cpp

@@ -99,8 +99,9 @@ float min_dist_moved = MIN_DIST;
 AXP20X_Class axp;
 bool pmu_irq = false;  // true when PMU IRQ pending
 
-bool ssd1306_found = false;
+bool oled_found = false;
 bool axp192_found = false;
+uint8_t oled_addr = 0; // i2c address of OLED controller
 
 bool packetQueued;
 bool isJoined = false;
@@ -498,7 +499,7 @@ void lora_msg_callback(uint8_t message) {
 void scanI2Cdevice(void) {
   byte err, addr;
   int nDevices = 0;
-  for (addr = 1; addr < 127; addr++) {
+  for (addr = 1; addr < 0x7F; addr++) {
     Wire.beginTransmission(addr);
     err = Wire.endTransmission();
     if (err == 0) {
@@ -511,9 +512,10 @@ void scanI2Cdevice(void) {
 #endif
       nDevices++;
 
-      if (addr == SSD1306_ADDRESS) {
-        ssd1306_found = true;
-        Serial.println("SSD1306 OLED display");
+      if (addr == 0x3C || addr == 0x78 || addr == 0x7E) {
+        oled_addr = addr;
+        oled_found = true;
+        Serial.printf("OLED at %02X\n", oled_addr);
       }
       if (addr == AXP192_SLAVE_ADDRESS) {
         axp192_found = true;
@@ -720,11 +722,11 @@ void setup() {
   // Don't init display if we don't have one or we are waking headless due to a
   // timer event
   if (0 && wakeCause == ESP_SLEEP_WAKEUP_TIMER)
-    ssd1306_found = false;  // forget we even have the hardware
+    oled_found = false;  // forget we even have the hardware
 
   // This creates the display object, so if we don't call it.. all screen ops are do-nothing.
-  if (ssd1306_found)
-    screen_setup();
+  if (oled_found)
+    screen_setup(oled_addr);
   is_screen_on = true;
 
   // GPS power on, so it has time to setttle.
@@ -794,7 +796,7 @@ void low_power_sleep(uint32_t seconds) {
   if (axp192_found) {
     axp.setPowerOutPut(AXP192_LDO3, AXP202_ON);  // GPS power
     // axp.setPowerOutPut(AXP192_DCDC1, AXP202_ON);  // OLED power
-    // if (ssd1306_found)
+    // if (oled_found)
     //  screen_setup();
   }
 

main/screen.cpp

@@ -25,6 +25,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <Wire.h>
 
 #include "OLEDDisplay.h"
+#include "SH1106Wire.h"
 #include "SSD1306Wire.h"
 #include "configuration.h"
 #include "credentials.h"
@@ -34,9 +35,12 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #define SCREEN_HEADER_HEIGHT 24
 
-SSD1306Wire *display;
+OLEDDisplay *display;
 uint8_t _screen_line = SCREEN_HEADER_HEIGHT - 1;
 
+enum display_types { DISPLAY_UNKNOWN, DISPLAY_SSD1306, DISPLAY_SH1106 };
+enum display_types display_type = DISPLAY_UNKNOWN;
+
 void screen_show_logo() {
   if (!display)
     return;
@@ -99,9 +103,77 @@ void screen_update() {
     display->display();
 }
 
-void screen_setup() {
+/*
+ * The SSD1306 and SH1106 controllers are almost the same, but different.
+ * Most importantly here, the SH1106 allows reading from the frame buffer, while the SSD1306 does not.
+ * We exploit this by writing two bytes and reading them back.  A mismatch probably means SSD1306.
+ * Probably.
+ */
+enum display_types display_get_type(uint8_t id) {
+  uint8_t err;
+  uint8_t b1, b2;
+
+  Wire.begin(I2C_SDA, I2C_SCL);
+  Wire.setClock(7000000);
+
+  Wire.beginTransmission(id);
+  uint8_t a[] = {0, 0, 0x10, 0xB0};
+  Wire.write(a, sizeof(a));
+  if ((err = Wire.endTransmission(false)) != 0) {
+    Serial.printf("err=%d EndTransmission=%d(%s)", err, Wire.lastError(), Wire.getErrorText(Wire.lastError()));
+    return DISPLAY_UNKNOWN;
+  }
+
+  Wire.beginTransmission(id);
+  uint8_t b[] = {0x40, 'M', 'P'};
+  Wire.write(b, sizeof(b));
+  if ((err = Wire.endTransmission(false)) != 0) {
+    Serial.printf("err=%d EndTransmission=%d(%s)", err, Wire.lastError(), Wire.getErrorText(Wire.lastError()));
+    return DISPLAY_UNKNOWN;
+  }
+
+  Wire.beginTransmission(id);
+  uint8_t c[] = {0, 0, 0x10};
+  Wire.write(c, sizeof(c));
+  if ((err = Wire.endTransmission(false)) != 0) {
+    Serial.printf("err=%d EndTransmission=%d(%s)", err, Wire.lastError(), Wire.getErrorText(Wire.lastError()));
+    return DISPLAY_UNKNOWN;
+  }
+
+  Wire.beginTransmission(id);
+  Wire.write(0x40);
+  if ((err = Wire.endTransmission(false)) != 0) {
+    Serial.printf("err=%d EndTransmission=%d(%s)", err, Wire.lastError(), Wire.getErrorText(Wire.lastError()));
+    return DISPLAY_UNKNOWN;
+  }
+
+  err = Wire.requestFrom((int)id, (int)3, (int)1);
+  if (err != 3) {
+    return DISPLAY_UNKNOWN;
+  }
+  Wire.read();  // Discard
+  b1 = Wire.read();
+  b2 = Wire.read();
+  Wire.endTransmission();
+
+  if (b1 == 'M' && b2 == 'P')
+    return DISPLAY_SH1106;
+  else
+    return DISPLAY_SSD1306;
+}
+
+void screen_setup(uint8_t addr) {
+  /* Attempt to determine which kind of display we're dealing with */
+  if (display_type == DISPLAY_UNKNOWN)
+    display_type = display_get_type(addr);
+
   // Display instance
-  display = new SSD1306Wire(SSD1306_ADDRESS, I2C_SDA, I2C_SCL);
+  if (display_type == DISPLAY_SSD1306)
+    display = new SSD1306Wire(addr, I2C_SDA, I2C_SCL);
+  else if (display_type == DISPLAY_SH1106)
+    display = new SH1106Wire(addr, I2C_SDA, I2C_SCL);
+  else
+    return;
   display->init();
   display->flipScreenVertically();
   display->setFont(Custom_ArialMT_Plain_10);

main/screen.h

@@ -16,5 +16,5 @@ void screen_off(void);
 void screen_on(void);
 
 void screen_show_logo(void);
-void screen_setup(void);
+void screen_setup(uint8_t addr);
 void screen_end(void);

tbeam-workspace.code-workspace

@@ -13,7 +13,8 @@
 			"string": "cpp",
 			"unordered_map": "cpp",
 			"unordered_set": "cpp",
-			"initializer_list": "cpp"
+			"initializer_list": "cpp",
+			"*.tcc": "cpp"
 		}
 	}
 }