User Manual

AT75C220
42
MAC Receive Buffer Queue Pointer
Register Name: ETH_RBQP
Access Type: Read/write
Reset Value: 0x0
• ADDRESS
Receive buffer queue pointer. Written with the address of the start of the receive queue, reads as a pointer to the cur-
rent buffer being used. The receive buffer is forced to word alignment.
MAC Receive Status Register
Register Name: ETH_RSR
Access Type: Read/write
Reset Value: 0x0
• BNA
Buffer not available. An attempt was made to get a new buffer and the pointer indicated that it was owned by the pro-
cessor. The DMA will reread the pointer each time a new frame starts until a valid pointer is found. This bit will be set at
each attempt that fails even if it has not had a successful pointer read since it has been cleared. Cleared by writing a
one to this bit.
• REC
Frame received. One or more frames have been received and placed in memory. Cleared by writing a one to this bit.
• OVR
RX overrun. The DMA block was unable to store the receive frame to memory, either because the ASB bus was not
granted in time or because a not OK HRESP was returned. The buffer will be recovered if this happens. Cleared by
writing a one to this bit.
31 30 29 28 27 26 25 24
ADDRESS
23 22 21 20 19 18 17 16
ADDRESS
15 14 13 12 11 10 9 8
ADDRESS
76543210
ADDRESS
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––OVR REC BNA