4.6.2 Internal Fault Detection

The LAN8650/1 includes the ability to detect various internal faults. These faults may be the result of signal noise, electromagnetic interference, high-energy particle radiation, or a latent device defect. When these faults occur the device can perform a safe action and alert the host controller to the fault for additional action in safety critical applications.

Finite state machines related to the transfer of packet data have the ability to detect an invalid transition or a transition into an invalid state. When these faults are detected, the Finite State Machine State Error (FSMSTER) status bit in the OPEN Alliance Status 1 (OA_STATUS1) register is set. If enabled, the setting of this bit will generate an interrupt to the host controller. When this fault occurs, the host controller must perform a hardware or software reset of the device.

Errors in the internal processing of transmit and receive Ethernet frames through the device are also detectable. When an internal error is detected on the transfer of a transmit frame from the SPI to the integrated MAC, the Transmit Non-recoverable Error (TXNER) status bit in OA_STATUS1 is set. Similarly, errors detected on the transfer of receive frames from the MAC to the SPI will set the Receive Non-recoverable Error (RXNER) status bit. When these faults occur, the transfer of Ethernet frames through the device is halted. If enabled, the setting of these bits will generate an interrupt to the host controller which must then perform a hardware or software reset of the device.

Additional fault detection features are described in the following sections.