Tedd OKANO / Mbed 2 deprecated pca9547_Hello

HelloWorld program for PCA9547: an I2C bus multiplexer control library. PCA9547 is an I2C multiplexer which enables to select 1:8 multiplexed I2C bus. The multiplexer is useful for deviding I2C bus to avoiding slave address conflict and separating capacitive loads. For more information about PCA9547: http://www.nxp.com/documents/data_sheet/PCA9547.pdf

Dependencies:   LM75B PCA9547 mbed

What is this?

This is a sample code to demonstrate the PCA9547. The PCA9547 is a 8 channel multiplexer for I2C bus.
The code shows how the bed can access the I2C device (LM75B) through PCA9547.

PCA9547_and_LM75B
Demo hardware block diagram

/media/uploads/okano/pca9547_connections.png
Connection between mbed and PCA9547

Information

For more information, please visit component page.

The PCA9547 is an octal bidirectional translating multiplexer controlled by the I2C-bus. The SCL/SDA upstream pair fans out to eight downstream pairs, or channels.

main.cpp

Committer:
okano
Date:
2014-06-30
Revision:
0:fb906b7b1452
Child:
1:63d8f8d68f61

File content as of revision 0:fb906b7b1452:

#include "mbed.h"
#include "LM75B.h"


I2C     i2c( p28, p27 );

void set_pca9547( char ch )
{
    char    v   = 0x08 | ch;
    i2c.write( 0xE0, &v, 1 );
}

int main()
{
    set_pca9547( 0 );

    LM75B   tmp0( p28, p27 );   //  making instance after a branch of I2C bus (which is connecting the LM75B) enabled

    while(1) {
        printf( "%.3f\r\n", tmp0.read() );
        wait( 1.0 );
    }
}