DM9161的物理地址确定方法

DM9161的物理地址是通过接收的4个脚26到29（与RXD3—RXD0复用）以及35脚CRS/PHYAD4来确定的。具体来说，就是在上电复位的时候，根据这几个脚的高电平来确定地址。

比如我手头的板子上采用的RMMI，只接了RXD0，RXD1，其他几个脚空着，所以上电时只有RXD0与RXD1是高电平，因此DM9161物理地址为3.

还有一个方法也可以很好的确定其物理地址。就是采用查询的方法，DM9161的物理地址肯定是0—31，比如DM9161的寄存器2的内容恒定为0x181，把物理地址0—31依次试一次，能从寄存器2读出来0x181的就是实际的物理地址。

实现代码如下：(atmel的代码)

//-----------------------------------------------------------------------------

/// Find a valid PHY Address ( from 0 to 31 ).

/// Check BMSR register ( not 0 nor 0xFFFF )

/// Return 0xFF when no valid PHY Address found.

/// \param pDm          Pointer to the Dm9161 instance

//-----------------------------------------------------------------------------

static unsigned char DM9161_FindValidPhy(Dm9161 * pDm)

{

    unsigned int  retryMax;

    unsigned int  value=0;

    unsigned char rc;

    unsigned char phyAddress;

    unsigned char cnt;

 

    TRACE_DEBUG("DM9161_FindValidPhy\n\r");

    ASSERT(pDm, "F: DM9161_FindValidPhy\n\r");

 

    EMAC_EnableMdio();

    phyAddress = pDm->phyAddress;

    retryMax = pDm->retryMax;

 

    // Check current phyAddress

    rc = phyAddress;

    if( EMAC_ReadPhy(phyAddress, DM9161_PHYID1, &value, retryMax) == 0 ) {

        TRACE_ERROR("DM9161 PROBLEM\n\r");

    }

    TRACE_DEBUG("_PHYID1  : 0x%X, addr: %d\n\r", value, phyAddress);

 

    // Find another one

    if (value != DM9161_OUI_MSB) {

 

        rc = 0xFF;

        for(cnt = 0; cnt < 32; cnt ++) {

 

            phyAddress = (phyAddress + 1) & 0x1F;

            if( EMAC_ReadPhy(phyAddress, DM9161_PHYID1, &value, retryMax) == 0 ) {

                TRACE_ERROR("DM9161 PROBLEM\n\r");

            }

            TRACE_DEBUG("_PHYID1  : 0x%X, addr: %d\n\r", value, phyAddress);

            if (value == DM9161_OUI_MSB) {

 

                rc = phyAddress;

                break;

            }

        }

    }

   

    EMAC_DisableMdio();

    if (rc != 0xFF) {

 

        TRACE_INFO("** Valid PHY Found: %d\n\r", rc);

        EMAC_ReadPhy(phyAddress, DM9161_DSCSR, &value, retryMax);

        TRACE_DEBUG("_DSCSR  : 0x%X, addr: %d\n\r", value, phyAddress);

 

    }

    return rc;

}