SI4844

Silicon Labs SI4844 (BROADCAST ANALOG TUNING DIGITAL DISPLAY AM/FM/SW RADIO RECEIVER) Library

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Making the Si4844 works with 5V Arduino UNO or similar

The SI4844 device works with +3.3V only. If you are not using a +3.3V version of Arduino, you have to use a kind of converter. I have tested it with success by using the I2C Multiplexer TCA9548A and Arduino UNO. However, during my attempts, just using a regular bidirectional voltage converter was not enough. I mean, It has not worked properly due to I2C communication requirement (I guess). So I have used the TCA9548A as a I2C bidirectional converter and a regular voltage converter to the digital pins, RESET and INTERRUPT. If you follow the idea of the schematic below you will get success.

I used what I had in my hands. However, I think there are other kind of components or methods that can be better than my approach.

The schematic below shows that approach.

Making the Si4844 works with 5V Arduino UNO or similar

IMPORTANT: You have to include in your sketch (setup function) these three lines:

  Wire.beginTransmission(0x70);
  Wire.write(1 << channel);
  Wire.endTransmission(); 

where channel is the port that you have choosen to connect the arduino to the Si4844. The schematic above shows channel (port) 0. So, the code should be:

  Wire.beginTransmission(0x70);
  Wire.write(1); // Yes. In this particular case just Wire.write(1). See the C/C++ "<<" for more detail.
  Wire.endTransmission(); 

if you choose the port 7

  Wire.beginTransmission(0x70);
  Wire.write(1 << 7); 
  Wire.endTransmission(); 

The table below show the possibilities to select an I2C channel on TCA9548A.

channel / port byte to send
0 00000001
1 00000010
2 00000100
3 00001000
4 00010000
5 00100000
6 01000000
7 10000000

You can also implement the function below in your code

inline void selectChannel(byte ch) {
  if ( ch < 8 ) {
    Wire.beginTransmission(0x70); // The const hex 0x70 is the TCA9548A I2C address
    Wire.write(1 << ch); 
    Wire.endTransmission(); 
  }  
}

References

Video about TCA9548A