Texas Instruments TNETE100A, TNETE211 manual Is the read op code for an MII management operation

MII PHY Registers

This samples data on the rising edge of the MCLK bit. Take the first bit into the PHY MII as follows:

b &= ~MCLK; outp(diodata,b);

b = MDATA; outp(diodata,b);

b = MCLK; outp(diodata,b); //1 data bit out

This concludes writing out the start delimiter bits. The data can be changed before the clock is taken low, as when shifting out the operation code as fol- lows:

b = MDATA; outp(diodata,b);	//1st part not nec.
//togLH
b &= ~MCLK; outp(diodata,b);
b = MCLK; outp(diodata,b);	//1
b &= ~MDATA; outp(diodata,b);
//togLH
b &= ~MCLK; outp(diodata,b);
b = MCLK; outp(diodata,b);	//0

10 is the read op code for an MII management operation.

//Send the device number Internal=31(0x1f), External=0(0x00)

for (i = 0x10;i;i >>= 1) /* 10 is the read op code*/

{

if (i&dev)

b = MDATA;

else

b &= ~MDATA;

outp(diodata,b);

//togLH

b &= ~MCLK; outp(diodata,b); b = MCLK; outp(diodata,b);

}

The following loop index is used as a mask to walk through the device number which is passed to this routine as a parameter. Each loop looks at a bit in the device number, starting with the MSB. It sets the MDATA bit to match the inter- nal representation of the NetSio register before outputting the composite value

ThunderLAN Registers 2-21