After I plugged in the LED matrix to the Rainbowduino and used the 5v output from the Arduino UNO to power up the Rainbowduino, only some LED on the matrix were on.(a picture of the LED matrix is attached) According to the video tutorial, aren’t all the LED should on?
When I uploaded both firmwares for the Aduino UNO and Rainbowduino and connected them using I2C, there was nothing happen. The matrix was still the same pattern.
The Rainbowduino needs more supply voltage to get all the LEDs working, at least 6.5V in the external power socket.
The Rainbowduino firmware by default displays a static startup pattern, you need to feed it commands via I2C or custom firmware to make it do something else.