Memory Interfaces
4-23
Memory Interface Traffic Controller
4.3.2.8
Asynchronous Write With WE Operation
The asynchronous write is used for both file flash and burst flash devices.
Figure 4–7 shows the timing diagram. Burst write operation is not supported.
Figure 4–7. Asynchronous Write With WE Operation
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FLASH.WE
Data to Flash
WRWST = 1
FLASH.CS_[X]
FLASH.ADV
FLASH.A
FLASH.CLK
FLASH.D
Address valid
WELEN = 2
The flash device latches the data on the rising edge of FLASH.WE; data hold
time specified is 0 ns minimum, which can be ensured by one TC clock cycle.
The FLASH.WE low pulse duration is programmable for each device through
the WELEN field in the flash configuration register. The number of wait states
between write operations is programmable for each device through the
WRWST field in the configuration register.
The duration from falling FLASH.CS to falling FLASH.WE (shown in
Figure 4–7) is equal to the programmed value of WRWST + 1, and the duration
for which FLASH.WE is asserted active low is equal to the programmed value
of WELEN + 1.
The FLASH.CLK signal is not driven externally (maintained low) in the asyn-
chronous write mode.