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Two Qualia RGB-666 Eyes Synced
What's better than one big Qualia-powered display? Two! You can sync two Qualia S3 boards together with a STEMMA QT cable to show a set of two coordinated eyeballs on two different round displays.
- One board acts as the primary, showing the left eye, and sending commands to sync gaze, pupil and blink actions.
- The secondary receives these commands and outputs them to the matching right eye.
There is a primary sketch and a secondary sketch that is uploaded to each board. Both are embedded below.
I2C and Qualia S3
One very important note for syncing two Qualia boards together: you need to change the default I2C address for the onboard I2C GPIO expander on one of the boards. Since the syncing takes place with a STEMMA QT connector, that means that during boot up the boards are sharing an I2C bus. If both boards are initializing their displays on the same I2C address, then things will get messy.
To change the address, either solder or cut jumpers on the front. In the photo, jumper A0 has been cut; setting the I2C address to 0x3E.
Text emphasized with a yellow exclamation:
You need to change the default I2C address on one of the Qualia S3 boards before syncing them together!
This 4-wire cable is a little over 100mm / 4" long and fitted with JST-SH female 4-pin connectors on both ends....
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If you need some extra distance between the display and board, you can use a 40-pin FPC extension board and ribbon cable.
Give your 40 pin, 0.5mm pitch, devices a strrrreeeetch with this extension board. This 40pin FPC extension board has...
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Display and I2C Init
Each display has its own initialization sequence that needs to be passed to start up the display. The example has these inits commented out with the 2.1" display uncommented as the default. If you've ever run Arduino code for the Qualia S3 before, these will look familiar to you.
Arduino_ESP32RGBPanel rgbpanel(
TFT_DE, TFT_VSYNC, TFT_HSYNC, TFT_PCLK, TFT_R1, TFT_R2, TFT_R3, TFT_R4,
TFT_R5, TFT_G0, TFT_G1, TFT_G2, TFT_G3, TFT_G4, TFT_G5, TFT_B1, TFT_B2,
TFT_B3, TFT_B4, TFT_B5,
1 /* HSYNC polarity */, 50 /* front porch */, 2 /* pulse width */,
44 /* back porch */,
1 /* VSYNC polarity */, 16 /* front porch */, 2 /* pulse width */,
18 /* back porch */);
// 4.0" 720x720 round display
// 1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
// 1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */);
Arduino_RGB_Display gfx(
// 2.1" 480x480 round display
RGB_W, RGB_H, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
&expander, GFX_NOT_DEFINED /* RST */, TL021WVC02_init_operations, sizeof(TL021WVC02_init_operations));
// 2.8" 480x480 round display
// 480 /* width */, 480 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, TL028WVC01_init_operations, sizeof(TL028WVC01_init_operations));
// 4.0" 720x720 round display
// 720 /* width */, 720 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, hd40015c40_init_operations, sizeof(hd40015c40_init_operations));
// needs also the rgbpanel to have these pulse/sync values:
// 1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
// 1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */
Make sure to update the I2C address for the GPIO expander for whichever board you changed the address for.
Arduino_XCA9554SWSPI expander(PCA_TFT_RESET, PCA_TFT_CS, PCA_TFT_SCK,
PCA_TFT_MOSI, &Wire, 0x3F);
Example Code - Primary Board
After installing the Monster Eyes library, upload this sketch to the primary Qualia S3 board.
// Adafruit Monster Eyes -- primary for Qualia ESP32-S3 sync
//
// Upload Qualia_Sync_Primary to one board and Qualia_Sync_Secondary to the
// other, with the same config.eye and assets on both.
//
// WIRING: one STEMMA QT cable between the two boards or connect SDA to SDA, SCL to SCL
// ----------- IMPORTANT NOTE ON I2C -----------
// The Qualia inits a display with the onboard I2C GPIO expander. Because of this, the
// two boards CANNOT have the same IO expander address and be connected on boot. You either
// need to change one of the onboard jumpers or have the boards fully boot and then
// connect the STEMMA QT cable.
#include <Adafruit_Monster_Eyes.h>
#include <Arduino_GFX_Library.h>
#include <Eyes_Sync.h>
#define RGB_W 480
#define RGB_H 480
#define EYE_SCALE 2 // Panel pixels per rendered pixel
Arduino_XCA9554SWSPI expander(PCA_TFT_RESET, PCA_TFT_CS, PCA_TFT_SCK,
PCA_TFT_MOSI, &Wire, 0x3F);
Arduino_ESP32RGBPanel rgbpanel(
TFT_DE, TFT_VSYNC, TFT_HSYNC, TFT_PCLK, TFT_R1, TFT_R2, TFT_R3, TFT_R4,
TFT_R5, TFT_G0, TFT_G1, TFT_G2, TFT_G3, TFT_G4, TFT_G5, TFT_B1, TFT_B2,
TFT_B3, TFT_B4, TFT_B5,
// 1 /* HSYNC polarity */, 50 /* front porch */, 2 /* pulse width */,
// 44 /* back porch */,
// 1 /* VSYNC polarity */, 16 /* front porch */, 2 /* pulse width */,
// 18 /* back porch */);
// 4.0" 720x720 round display
1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */);
Arduino_RGB_Display gfx(
// 2.1" 480x480 round display
// RGB_W, RGB_H, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, TL021WVC02_init_operations, sizeof(TL021WVC02_init_operations));
// 2.8" 480x480 round display
// 480 /* width */, 480 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, TL028WVC01_init_operations, sizeof(TL028WVC01_init_operations));
// 4.0" 720x720 round display
720 /* width */, 720 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
&expander, GFX_NOT_DEFINED /* RST */, hd40015c40_init_operations, sizeof(hd40015c40_init_operations));
// needs also the rgbpanel to have these pulse/sync values:
// 1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
// 1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */
Adafruit_Monster_Eyes eyes(&gfx, EYE_SCALE);
Eyes_SyncPrimary eyeSync(eyes); // Defaults: Wire, address 0x42, right eye
void setup() {
Serial.begin(115200);
eyes.setVerbose(Serial);
Wire.setClock(1000000);
if (!eyes.begin()) {
Serial.print("Monster Eyes failed: ");
Serial.println(eyes.errorString());
while (1)
delay(1000);
}
expander.pinMode(PCA_TFT_BACKLIGHT, OUTPUT);
expander.digitalWrite(PCA_TFT_BACKLIGHT, HIGH);
eyeSync.begin();
}
void loop() {
eyes.animate();
eyeSync.send();
static uint32_t last = 0;
if (millis() - last >= 1000) {
last = millis();
Serial.printf("%.0f fps\n", eyes.frameRate());
Serial.printf("sync: sent %lu, failed %lu\n", eyeSync.sent(),
eyeSync.failed());
eyeSync.resetCounts();
}
}
Example Code - Secondary Board
After installing the Monster Eyes library, upload this sketch to the secondary Qualia S3 board.
// Adafruit Monster Eyes -- primary for Qualia ESP32-S3 sync
//
// Upload Qualia_Sync_Primary to one board and Qualia_Sync_Secondary to the
// other, with the same config.eye and assets on both.
//
// WIRING: one STEMMA QT cable between the two boards or connect SDA to SDA, SCL to SCL
// ----------- IMPORTANT NOTE ON I2C -----------
// The Qualia inits a display with the onboard I2C GPIO expander. Because of this, the
// two boards CANNOT have the same IO expander address and be connected on boot. You either
// need to change one of the onboard jumpers or have the boards fully boot and then
// connect the STEMMA QT cable.
#include <Adafruit_Monster_Eyes.h>
#include <Arduino_GFX_Library.h>
#include <Eyes_Sync.h>
#define RGB_W 480
#define RGB_H 480
#define EYE_SCALE 2 // Panel pixels per rendered pixel
Arduino_XCA9554SWSPI expander(PCA_TFT_RESET, PCA_TFT_CS, PCA_TFT_SCK,
PCA_TFT_MOSI, &Wire, 0x3F);
Arduino_ESP32RGBPanel rgbpanel(
TFT_DE, TFT_VSYNC, TFT_HSYNC, TFT_PCLK, TFT_R1, TFT_R2, TFT_R3, TFT_R4,
TFT_R5, TFT_G0, TFT_G1, TFT_G2, TFT_G3, TFT_G4, TFT_G5, TFT_B1, TFT_B2,
TFT_B3, TFT_B4, TFT_B5,
1 /* HSYNC polarity */, 50 /* front porch */, 2 /* pulse width */,
44 /* back porch */,
1 /* VSYNC polarity */, 16 /* front porch */, 2 /* pulse width */,
18 /* back porch */);
// 4.0" 720x720 round display
// 1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
// 1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */);
Arduino_RGB_Display gfx(
// 2.1" 480x480 round display
RGB_W, RGB_H, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
&expander, GFX_NOT_DEFINED /* RST */, TL021WVC02_init_operations, sizeof(TL021WVC02_init_operations));
// 2.8" 480x480 round display
// 480 /* width */, 480 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, TL028WVC01_init_operations, sizeof(TL028WVC01_init_operations));
// 4.0" 720x720 round display
// 720 /* width */, 720 /* height */, &rgbpanel, 0 /* rotation */, true /* auto_flush */,
// &expander, GFX_NOT_DEFINED /* RST */, hd40015c40_init_operations, sizeof(hd40015c40_init_operations));
// needs also the rgbpanel to have these pulse/sync values:
// 1 /* hync_polarity */, 46 /* hsync_front_porch */, 2 /* hsync_pulse_width */, 44 /* hsync_back_porch */,
// 1 /* vsync_polarity */, 50 /* vsync_front_porch */, 16 /* vsync_pulse_width */, 16 /* vsync_back_porch */
Adafruit_Monster_Eyes eyes(&gfx, EYE_SCALE);
Eyes_SyncSecondary eyeSync(eyes); // Defaults: Wire, address 0x42, left eye
void setup() {
Serial.begin(115200);
eyes.setVerbose(Serial);
Wire.setClock(1000000);
if (!eyes.begin()) {
Serial.print("Monster Eyes failed: ");
Serial.println(eyes.errorString());
while (1)
delay(1000);
}
expander.pinMode(PCA_TFT_BACKLIGHT, OUTPUT);
expander.digitalWrite(PCA_TFT_BACKLIGHT, HIGH);
Wire.end();
Wire.setPins(SDA, SCL); // end() forgets them on some core versions
eyeSync.begin();
}
void loop() {
eyeSync.poll(); // Takes over gaze, pupil and lids while packets arrive
eyes.animate();
static uint32_t last = 0;
if (millis() - last >= 1000) {
last = millis();
Serial.printf("%.0f fps\n", eyes.frameRate());
eyeSync.report(Serial);
eyeSync.resetCounts();
}
}
Page last edited September 23, 2026
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