MCP23016

[Richi]

Hi Friends,
want to use a MCP23016. Now I think my code is o.k... I measured with a oszilloskop and can´t find an error, The initial sequenz (I/O direction) is sended but if I read from any registerpair I always get 0xFF in the WATCH window- as I also can se on the oszilloskop. So the adress and everything is o.k. I also get an acknolage.
Second: the INT Pin is always low- but maybe it is because the part is not initialized?

(Is it really necessary to give a 20µs delay between every Write/read? What about using the Fast-mode?)

The Code:

void Write_I2C_MCP ( int MCP_Commando, long MCP_Data )
{
MCP_Data_L = make8(MCP_Data,0);
MCP_Data_H = make8(MCP_Data,1);

I2C_start();
delay_us(20);
I2C_write( 0x40 ); // Adresse
delay_us(20);
I2C_write( MCP_Commando );
delay_us(20);
I2C_write( MCP_Data_H );
delay_us(20);
I2C_write( MCP_Data_L );
delay_us(20);
I2C_stop();
delay_us(20);

}


int Read_I2C_MCP ( int MCP_Commando )
{

I2C_start();
delay_us(20);
I2C_write( 0x40 ); // Adresse
delay_us(20);
I2C_write( MCP_Commando );
delay_us(20);
I2C_write( 0x41 ); // Adresse
delay_us(20);
MCP_Data_lesen_H = I2C_read();
delay_us(20);
MCP_Data_lesen_L = I2C_read();
delay_us(20);
I2C_stop();
delay_us(20);
return(MCP_Data_lesen_L, MCP_Data_lesen_H);
}






#INT_EXT
void isr_ext()
{
NOP;
}

void main (void)
{
enable_interrupts(GLOBAL);
enable_interrupts(INT_EXT);
EXT_INT_EDGE(H_TO_L);

Write_I2C_MCP ( 0x04, 0x0000 );
Write_I2C_MCP ( 0x0A, 0x0101 );

Write_I2C_MCP ( 0x06, 0xC700 );
delay_ms(1);
Write_I2C_MCP ( 0x02, 0x0000 );

for (;;)
{
Read_I2C_MCP ( 0x06 );

Read_I2C_MCP ( 0x08 );

Write_I2C_MCP ( 0x00, 0xFF00 );
}
}

[PCM programmer]

There's a driver for the MCP23016 in the code forum:
http://www.ccsinfo.com/forum/viewtopic.php?t=21797

Also, if you had logged in, then you could delete the double post
that you made. Guests can't delete their extra posts.

[Richi]

Hi PCM,

I already had seen this sample C-File. And I found out that my programm is nearly the same. But it didn´t work! WHY? After a third and fourt compare I found out that i forgot to send a new start condition when reading...

Thanks