712
/
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Nations Technologies Inc.
Tel
：
+86-755-86309900
：
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
RMII has only one clock signal of 50MHz, both MAC and external PHY need to use this clock source, and transmit
and receive data are transmitted through 2-bit line width respectively.
Figure 25-6 RMII interface signal line
RMII clock source
As shown in the figure below, an external clock source or by configuring a suitable PLL, the clock output pin MCO
of the MCU can provide a 50MHz clock signal.
Figure 25-7 RMII clock source
25.4.6
MAC function description
The MAC module performs the encapsulation of transmitted data and received data, and supports half-duplex or full-
duplex working modes. Data encapsulation enables frame detection/decoding, frame boundary delimitation,
addressing (managing source and destination addresses), and error detection. In half-duplex mode, the CSMA/CD
algorithm is used to preempt access to the physical medium, and only two sites in one transmission direction are valid
MAC controller
PHY
RMII_Tx_EN
RMII_TxD[1:0]
RMII_CRS_DV
RMII_RxD[1:0]
RMII_REF_CLK
MCO
PLL
M
A
C
8
0
2
.3
25 MHz
PHY
50 MHz
50 MHz
REF_CLK
N32G45x
