MMC control register
| CNTRST | Counters Reset When this bit is set, all counters are reset. This bit is cleared automatically after 1 clock cycle. |
| CNTSTOPRO | Counter Stop Rollover When this bit is set, the counter does not roll over to zero after reaching the maximum value. |
| RSTONRD | Reset on Read When this bit is set, the MMC counters are reset to zero after Read (self-clearing after reset). The counters are cleared when the least significant byte lane (Bits[7:0]) is read. |
| CNTFREEZ | MMC Counter Freeze When this bit is set, it freezes all MMC counters to their current value. Until this bit is reset to 0, no MMC counter is updated because of any transmitted or received packet. If any MMC counter is read with the Reset on Read bit set, then that counter is also cleared in this mode. |
| CNTPRST | Counters Preset When this bit is set, all counters are initialized or preset to almost full or almost half according to the CNTPRSTLVL bit. This bit is cleared automatically after 1 clock cycle. This bit, along with the CNTPRSTLVL bit, is useful for debugging and testing the assertion of interrupts because of MMC counter becoming half-full or full. |
| CNTPRSTLVL | Full-Half Preset When this bit is low and the CNTPRST bit is set, all MMC counters get preset to almost-half value. All octet counters get preset to 0x7FFF_F800 (Half 2Kbytes) and all packet-counters get preset to 0x7FFF_FFF0 (Half 16). When this bit is high and the CNTPRST bit is set, all MMC counters get preset to almost-full value. All octet counters get preset to 0xFFFF_F800 (Full 2Kbytes) and all packet-counters get preset to 0xFFFF_FFF0 (Full 16). For 16-bit counters, the almost-half preset values are 0x7800 and 0x7FF0 for the respective octet and packet counters. Similarly, the almost-full preset values for the 16-bit counters are 0xF800 and 0xFFF0. |
| UCDBC | Update MMC Counters for Dropped Broadcast Packets The CNTRST bit has a higher priority than the CNTPRST bit. Therefore, when the software tries to set both bits in the same write cycle, all counters are cleared and the CNTPRST bit is not set. When set, the MAC updates all related MMC Counters for Broadcast packets that are dropped because of the setting of the DBF bit of Packet filtering control register (ETH_MACPFR). When reset, the MMC Counters are not updated for dropped Broadcast packets. |