SNLS484J February 2015 – June 2026 DP83867CR , DP83867IR
PRODUCTION DATA
There are several options for Loopback that test and verify various functional blocks within the PHY. Enabling loopback mode allows in-circuit testing of the digital and analog data paths. Generally, the DP83867 can be configured to one of the Near-end loopback modes or to the Far-end (reverse) loopback. MII Loopback is configured using the BMCR (register address 0x0000). All other loopback modes are enabled using the BISCR (register address 0x16). Except where otherwise noted, loopback modes are supported for all speeds (10/100/1000) and all MAC interfaces (RGMII and GMII).
Figure 7-11 LoopbacksThe availability of Loopback depends on the operational mode of the PHY. The operation mode also affects the Link Status in these loopback modes. Table 7-4 lists out the availability of Loopback Modes and corresponding Link Status indication.
| LOOPBACK MODE | MAC INTERFACE | 1000M | 100M | 10M | |||
|---|---|---|---|---|---|---|---|
| AVAILABILITY | LINK STATUS | AVAILABILITY | LINK STATUS | AVAILABILITY | LINK STATUS | ||
| MII | GMII/RGMII | Yes | No | Yes | No | Yes | No |
| PCS | GMII/RGMII | Yes | No | Yes | Yes | No | No |
| Digital | GMII/RGMII | Yes | Yes | Yes | Yes | Yes | Yes |
| Analog | GMII/RGMII | Yes | Yes | Yes | Yes | Yes | Yes |
| External | GMII/RGMII | No | No | Yes | Yes | Yes | Yes |