MCIMX27 Motorola Semiconductor Products, MCIMX27 Datasheet - Page 56

• Manufacturer Part Number: MCIMX27
• Manufacturer: Motorola Semiconductor Products

Signal Descriptions
Figure 16
sensing grant signal active such that a new burst is not initiated.
3.5.8
This section describes the AC timing specifications of the FEC. The MII signals are compatible with
transceivers operating at a voltage of 3.3 V.
56
T
T
T
T
min_assert
max_req_assert
max_read
max_write
Parameter
External device
Ext_DMAGrant
Data written to
Ext_DMAReq
Data read from
External device
NOTE: Assuming worst case that the data is read/written from/to external device as per the above waveform.
shows the safe maximum time for which External DMA request can be kept asserted, after
Ext_DMAGrant
Fast Ethernet Controller (FEC)
Ext_DMAReq
Figure 16. Timing Diagram of Safe Maximums for External Request De-Assertion
Minimum assertion time of External Grant signal
Maximum External Request assertion time after
assertion of Grant signal
Maximum External Request assertion time after
first read completion
Maximum External Request assertion time after
first write completion
Figure 15. Assertion of DMA External Grant Signal
Description
i.MX27 Data Sheet, Advance Information, Rev. 0.1
Preliminary—Subject to Change Without Notice
Table 23. DMAC Timing Parameters
9hclk–20.66
8hclk–6.21
3hclk–5.87
8hclk+8.6
t
max_req_assert
WCS
3.0 V
t
min_assert
t
max_read
8hclk+2.74
8hclk–0.77
3hclk–8.83
9hclk–6.7
BCS
9hclk–17.96 9hclk–8.16
8hclk+7.17
8hclk–5.84
3hclk–15.9
WCS
Freescale Semiconductor
t
max_write
1.8 V
8hclk+3.25
8hclk–0.66
3hclkv91.2
BCS
Unit
ns
ns
ns
ns