HS_Media independent interface (MII)
RM0082
506/844
Doc ID 018672 Rev 1
Figure 50.
MAC-UNIV (MAC-AHB configuration) system-level block diagram
24.3
Main functions description
24.3.1 AHB
slave
interface
The AHB Slave Interface block allows the host CPU to access all the DMA and MAC control
and status registers (CSRs).
32 bit, 16 bit and 8 bit write/read transfers to CSRs are all supported by AHB Slave
Interface, but 32 bit access to CSRs are recommended to avoid any software
synchronization problems.
24.3.2
AHB master interface
In MAC-AHB configuration, the MAC-UNIV transfers data by DMA to system memory
through the AHB master interface.
In particular, the AHB master interfaces with the DMA controller and converts the internal
DMA request cycles into AHB cycles. Both fixed burst length (SINGLE, INCR4, INCR8,
INCR16) and unspecified burst length (SINGLE, INCR) transfer types are supported.
Note:
1
The DMA Controller should request an AHB Burst Read transfer only when it has the
capability of accepting the received burst data completely. Indeed, data read from AHB is
always pushed into the DMA without any delay.
2
The DMA Controller should request an AHB Burst Write transfer only when it has the
sufficient data to transfer the burst completely. Indeed, the AHB interface assumes that it
always has data available to push into the AHB bus.
RxFIFO
(Mem)
TxFIFO
(Mem)
AHB
Master
Interface
AHB
Slave
Interface
DMA
TxFC RxFC
DMA
CSR
OMR
Register
MAC
MAC
CSR
MAC-CORE
MAC-MTL
MAC-DMA
MAC-AHB