RM0090: Reference manual - STMicroelectronics

RM0090 Ethernet (ETH): media access control (MAC) with DMA controller
Table 165. Source address filtering
Frame type PM SAIF SAF SA filter operation
Unicast
29.5.6 MAC loopback mode
1 X X Pass all frames
0 0 0
Pass status on perfect/Group filter match but do not drop
frames that fail
0 1 0 Fail status on perfect/group filter match but do not drop frame
0 0 1 Pass on perfect/group filter match and drop frames that fail
0 1 1 Fail on perfect/group filter match and drop frames that fail
The MAC supports loopback of transmitted frames onto its receiver. By default, the MAC
loopback function is disabled, but this feature can be enabled by programming the Loopback
bit in the MAC ETH_MACCR register.
29.5.7 MAC management counters: MMC
The MAC management counters (MMC) maintain a set of registers for gathering statistics
on the received and transmitted frames. These include a control register for controlling the
behavior of the registers, two 32-bit registers containing generated interrupts (receive and
transmit), and two 32-bit registers containing masks for the Interrupt register (receive and
transmit). These registers are accessible from the application. Each register is 32 bits wide.
Section 29.8: Ethernet register descriptions describes the various counters and lists the
addresses of each of the statistics counters. This address is used for read/write accesses to
the desired transmit/receive counter.
The Receive MMC counters are updated for frames that pass address filtering. Dropped
frames statistics are not updated unless the dropped frames are runt frames of less than 6
bytes (DA bytes are not received fully).
Good transmitted and received frames
Transmitted frames are considered “good” if transmitted successfully. In other words, a
transmitted frame is good if the frame transmission is not aborted due to any of the following
errors:
+ Jabber Timeout
+ No Carrier/Loss of Carrier
+ Late Collision
+ Frame Underflow
+ Excessive Deferral
+ Excessive Collision
Doc ID 018909 Rev 3 930/1416