MCIMX25 Motorola Semiconductor Products, MCIMX25 Datasheet - Page 86

• Manufacturer Part Number: MCIMX25
• Manufacturer: Motorola Semiconductor Products

3.6.9.3
In RMII mode, FEC_TX_CLK is used as the REF_CLK, which is a 50 MHz ± 50 ppm continuous
reference clock. FEC_RX_DV is used as the CRS_DV in RMII. Other signals under RMII mode include
FEC_TX_EN, FEC_TXD[1:0], FEC_RXD[1:0] and FEC_RX_ER.
Figure 59
figure.
86
M16
M17
M18
M19
M20
M21
ID
FEC_TXD[1:0] (output)
FEC_TX_EN
FEC_RXD[1:0]
FEC_RX_ER
REF_CLK(FEC_TX_CLK) pulse width high
REF_CLK(FEC_TX_CLK) pulse width low
REF_CLK to FEC_TXD[1:0], FEC_TX_EN invalid
REF_CLK to FEC_TXD[1:0], FEC_TX_EN valid
FEC_RXD[1:0], CRS_DV(FEC_RX_DV), FEC_RX_ER to REF_CLK setup
REF_CLK to FEC_RXD[1:0], FEC_RX_DV, FEC_RX_ER hold
REF_CLK (input)
shows RMII mode timings.
CRS_DV (input)
RMII Mode Timing
i.MX25 Applications Processor for Consumer and Industrial Products, Rev. 2
Figure 59. RMII Mode Signal Timing Diagram
Characteristic
Table 62
Table 62. RMII Signal Timing
M20
M18
describes the timing parameters (M16–M21) shown in the
M21
M19
M16
M17
Min.
35%
35%
—
3
2
2
Max.
65%
65%
12
—
—
—
Freescale Semiconductor
REF_CLK period
REF_CLK period
Unit
ns
ns
ns
ns