MCIMX257DJM4 Freescale, MCIMX257DJM4 Datasheet - Page 89

• Manufacturer Part Number: MCIMX257DJM4
• Manufacturer: Freescale

Specifications of MCIMX257DJM4

• Operating Temperature (min): -20C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

3.7.9.3
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.
Freescale Semiconductor
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. 6
Figure 59. RMII Mode Signal Timing Diagram
Characteristic
Table 64
Table 64. 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
—
—
—
REF_CLK period
REF_CLK period
Unit
ns
ns
ns
ns
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