SNLS504E October 2015 – May 2024
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 may 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 (SGMII and RGMII).
The availability of Loopback depends on the operational mode of the PHY. The Link Status in these loopback modes is also affected by the operational mode. Table 7-4 lists out the availability of Loopback Modes and their corresponding Link Status indication.
LOOPBACK MODE | MAC INTERFACE | 1000M | 100M | 10M | |||
---|---|---|---|---|---|---|---|
AVAILABILITY | LINK STATUS | AVAILABILITY | LINK STATUS | AVAILABILITY | LINK STATUS | ||
MII | RGMII | Yes | No | Yes | No | Yes | No |
PCS | RGMII | Yes | No | Yes | Yes | No | No |
Digital | RGMII | Yes | Yes | Yes | Yes | Yes | Yes |
Analog | RGMII | Yes | Yes | Yes | Yes | Yes | Yes |
External | RGMII | No | No | Yes | Yes | Yes | Yes |
MII | SGMII | Yes | No | Yes | No | No | No |
Digital | SGMII | Yes | Yes | Yes | Yes | No | No |
IO | SGMII | Yes | Yes | Yes | Yes | No | No |