
Electrical Characteristics
i.MX51 Applications Processors for Consumer and Industrial Products, Rev. 4
Freescale Semiconductor
53
4.6.7
External Interface Module (WEIM)
The following sections provide information on the WEIM.
4.6.7.1
WEIM Signal Cross Reference
Table 51 is a guide to help the user identify signals in the WEIM Chapter of the i.MX51 Multimedia Applications Processor Reference Manual (MCIMX51RM) that are the same as those mentioned in this
data sheet.
NF21
WE high to RE low
tWHR
14T-5.45
—
NF22
WE high to busy
tWB
—
6T
1
tDSR is calculated by the following formula:
Asymmetric mode: tDSR = tREpd + tDpd + 1/
2T – Tdl
2
Symmetric mode: tDSR = tREpd + tDpd – Tdl2
tREpd + tDpd = 11.2 ns (including clock skew)
where tREpd is RE propogation delay in the chip including IO pad delay, and tDpd is Data propogation delay
from IO pad to EMI including IO pad delay.
tDSR can be used to determine tREA max parameter with the following formula: tREA = 1.5T – tDSR.
2
Tdl is composed of 4 delay-line units each generates an equal delay with min 1.25 ns and max 1 aclk
period (Taclk). Default is 1/4 aclk period for each delay-line unit, so all 4 delay lines together generates
a total of 1 aclk period. Taclk is “emi_slow_clk” of the system, which default value is 7.5 ns (133 MHz).
3
NF17 is defined only in asymmetric operation mode.
NF17 max value is equivalent to max tRHZ value that can be used with NFC.
Taclk is “emi_slow_clk” of the system.
4
NF18 is defined only in Symmetric operation mode.
tDHR (MIN) is calculated by the following formula:
Tdl2 – (tREpd + tDpd)
where tREpd is RE propogation delay in the chip including IO pad delay, and tDpd is Data propogation delay
from IO pad to EMI including IO pad delay.
NF18 max value is equivalent to max tRHZ value that can be used with NFC.
Taclk is “emi_slow_clk” of the system.
Table 51. WEIM Signal Cross Reference
Reference Manual
WEIM Chapter Nomenclature
Data Sheet Nomenclature,
Reference Manual External Signals and Pin Multiplexing Chapter,
and IOMUX Controller Chapter Nomenclature
BCLK
EIM_BCLK
CSx
EIM_CSx
WE_B
EIM_RW
OE_B
EIM_OE
BEy_B
EIM_EBx
ADV
EIM_LBA
Table 50. NFC—Timing Characteristics (continued)
ID
Parameter
Symbol
Asymmetric
Mode Min
Symmetric
Mode Min
Max