CY7C43643
CY7C43663
CY7C43683
Document #: 38-06021 Rev. *B
Page 11 of 29
Table 2. Flag Programming[2]
SPM
FS1/SEN
FS0/SD
MRS1/MRS2
X and Y Registers[3]
H
H
H
↑
64
H
H
L
↑
16
H
L
H
↑
8
H
L
L
↑
Parallel programming via Port A
L
H
L
↑
Serial programming via SD
L
H
H
↑
Reserved
L
L
H
↑
Reserved
L
L
L
↑
Reserved
Table 3. Port A Enable Function
CSA
W/RA
ENA
MBA
CLKA
A0–35 Outputs
Port Function
H
X
X
X
X
In high-impedance state
None
L
H
L
X
X
In high-impedance state
None
L
H
H
L
↑
In high-impedance state
FIFO write
L
H
H
H
↑
In high-impedance state
Mail1 write
L
L
L
L
X
Active, Mail2 register
None
L
L
H
L
↑
Active, Mail2 register
None
L
L
L
H
X
Active, Mail2 register
None
L
L
H
H
↑
Active, Mail2 register
Mail2 read (set MBF2 HIGH)
Table 4. Port B Enable Function
CSB
W/RB
ENB
MBB
CLKB
B0–35 Outputs
Port Function
H
X
X
X
X
In high-impedance state
None
L
L
L
X
X
In high-impedance state
None
L
L
H
L
↑
In high-impedance state
None
L
L
H
H
↑
In high-impedance state
Mail2 write
L
H
L
L
X
Active, FIFO output register
None
L
H
H
L
↑
Active, FIFO output register
FIFO read
L
H
L
H
X
Active, Mail1 register
None
L
H
H
H
↑
Active, Mail1 register
Mail1 read (set MBF1 HIGH)
Table 5. FIFO Flag Operation (CY Standard and FWFT Modes)[2]
Number of Words in FIFO Memory[4, 5, 6, 7]
Synchronized to CLKB Synchronized to CLKA
CY7C43643
CY7C43663
CY7C43683
EF/OR
AE
AF
FF/IR
0
0
0
L
L
H
H
1 TO X1
1 TO X1
1 TO X1
H
L
H
H
(X1+1) to [1024–(Y1+1)] (X1+1) to [4096–(Y1+1)] (X1+1) to [16384–(Y1+1)]
H
H
H
H
(1024–Y1) to 1023
(4096–Y1) to 4095
(16384–Y1) to 16383
H
H
L
H
1024
4096
16384
H
H
L
L
Notes:
3.
X register holds the offset for AE; Y register holds the offset for AF.
4.
X is the Almost Empty offset for FIFO used by AE. Y is the Almost Full offset for FIFO used by AF. Both X and Y are selected during a FIFO reset or port A
programming.
5.
When a word loaded to an empty FIFO is shifted to the output register, its previous FIFO memory location is free.
6.
Data in the output register does not count as a “word in FIFO memory”. Since in FWFT Mode, the first word written to an empty FIFO goes unrequested to the
output register (no read operation necessary), it is not included in the FIFO memory count.
7.
The OR and IR functions are active during FWFT mode; the EF and FF functions are active in CY Standard Mode.
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