IDT72511 View Datasheet(PDF) - Integrated Device Technology
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IDT72511 Datasheet PDF : 28 Pages
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IDT72511/IDT72521
BIDIRECTIONAL FIRST-IN FIRST-OUT MEMORY
MILITARY AND COMMERCIAL TEMPERATURE RANGES
prevent the data block from being read. In this case the
assertion of B->A empty flag will occur when the read pointer
meets the rewrite pointer instead of the write pointer.
In conclusion, Bit 2 and 3 of Configuration Register 5 are
used to redefine Full & Empty flags for data block partition.
Although it can serve the purpose of data protection, the
setting of these 2 bits is independent of the functions caused
by RER/REW, or LDRER/LDREW assertions.
Programmable Input/Output
The BiFlFO has six programmable I/0 pins (PlO0 - PIO5)
which are controlled by Port A through Configuration Regis-
ters 6 and 7. Data from the programmable I/O pins is mapped
directly to the six least significant bits of Configuration Regis-
ter 6. Figure 4 shows the format of Configuration Register 6.
This data is read or written by Port A on the data pins
(DA0- DA5). A programmed output PIOi pin (i = 0, 1, . . . , 5)
displays the data latched in Bit i of Configuration Register 6.
A programmed input PIOi pin allows Port A bus to sample its
data on DAi by reading Configuration Register 6. The read and
write timing for the programmable I/O pins is shown in Figure
19. The direction of each programmable I/O pin can be set
independently by programming the mask in Configuration
Register 7. Each P10 pin has a corresponding input/output
direction mask bit in Configuration Register 7. Figure 5 shows
the format of Configuration Register 7. Setting a mask bit to a
logic 1 makes the corresponding I/O pin an output. Mask bits
set to logic 0 force the corresponding I/O pin to an input.
REREAD OPERATIONS (1,2)
Reread
Pointer
Reread
function
REWRITE OPERATIONS (3,4)
Read
Pointer
Write
Pointer
A→B
FIFO
NOTES:
1. If bit 2 is set to 1,
Empty flag asserted if Read = Write
Full flag asserted if Reread + FIFO size = Write
2. If bit 2 is set to 0,
Empty flag asserted if Read = Write
Full flag asserted if Read + FIFO size = Write
Write
Pointer
B→A
FIFO
Load
Reread
function
Load Rewrite
function
Read
Pointer
2668 drw 08
Rewrite
function
Rewrite
Pointer
NOTES:
1. If bit 3 is set to 1,
Empty flag asserted if Read = Rewrite
Full flag asserted if Read + FIFO size = Write
2. If bit 3 is set to 0,
Empty flag asserted if Read = Write
Full flag asserted if Read + FIFO size = Write
2668 drw 09
Figure 6. BiFIFO Reread Operations
Figure 7. BiFIFO Rewrite Operations
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