FOR
FOR
CY7C68001
These flags can be programmed to represent various FIFO
flags using four select bits for each FIFO. The 4-bit coding for
all four flags is the same, as shown in the following table
Table 7-2. FIFO Flag 4-bit Coding
.
7.3.1
Bit 7: WUPOL
This flag sets the polarity of the WAKEUP pin. If WUPOL = 0
(default), the polarity is active LOW. If WUPOL=1, the polarity
is active HIGH.
7.3.2
Bit 5: PKTEND
FLAGx3 FLAGx2 FLAGx1 FLAGx0
0
0
0
0
Pin Function
FLAGA = PF,
FLAGB = FF,
FLAGC = EF,
FLAGD = CS#
(actual FIFO is
selected by
FIFOADR[2:0]
pins)
Reserved
Reserved
Reserved
EP2 PF
EP4 PF
EP6 PF
EP8 PF
EP2 EF
EP4 EF
EP6 EF
EP8 EF
EP2 FF
EP4 FF
EP6 FF
EP8 FF
This flag selects the polarity of the PKTEND pin. If PKTEND =
0 (default), the polarity is active LOW. If PKTEND = 1, the
polarity is active HIGH.
7.3.3
Bit 4: SLOE
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
This flag selects the polarity of the SLOE pin. If SLOE = 0
(default), the polarity is active LOW. If SLOE = 1, the polarity
is active HIGH. This bit can only be changed by using the
EEPROM configuration load.
7.3.4
Bit 3: SLRD
This flag selects the polarity of the SLRD pin. If SLRD = 0
(default), the polarity is active LOW. If SLRD = 1, the polarity
is active HIGH. This bit can only be changed by using the
EEPROM configuration load.
7.3.5
SLWR Bit 2
This flag selects the polarity of the SLWR pin. If SLWR = 0
(default), the polarity is active LOW. If SLWR = 1, the polarity
is active HIGH. This bit can only be changed by using the
EEPROM configuration load.
7.3.6
EF Bit 1
For the default (0000) selection, the four FIFO flags are fixed-
function as shown in the first table entry; the input pins
FIFOADR[2:0] select to which of the four FIFOs the flags
correspond. These pins are decoded as shown in
The other (non-zero) values of FLAGx[3:0] allow the designer
to independently configure the four flag outputs FLAGA-
FLAGD to correspond to any flag-Programmable, Full, or
Empty-from any of the four endpoint FIFOs. This allows each
flag to be assigned to any of the four FIFOs, including those
not currently selected by the FIFOADR [2:0] pins. For
example, the external master could be filling the EP2IN FIFO
with data while also checking the empty flag for the EP4OUT
FIFO.
This flag selects the polarity of the EF pin (FLAGA/B/C/D). If
EF = 0 (default), the EF pin is pulled low when the FIFO is
empty. If EF = 1, the EF pin is pulled HIGH when the FIFO is
empty.
7.3.7
FF Bit 0
This flag selects the polarity of the FF pin (FLAGA/B/C/D). If
FF = 0 (default), the FF pin is pulled low when the FIFO is full.
If FF = 1, the FF pin is pulled HIGH when the FIFO is full.
Note that bits 2(SLWR), 3(SLRD) and 4 (SLOE) are READ
only bits and cannot be set by the external master or the
EEPROM. On power-up, these bits are set to active low
polarity. In order to change the polarity after the device is
powered-up, the external master must access the previously
undocumented (un-indexed)
SX2
register located at XDATA
space at 0xE609. This register has exact same bit definition
as the POLAR register except that bits 2, 3 and 4 defined as
SLWR, SLRD and SLOE respectively are Read/Write bits.
Following is the sequence of events that the master should
perform for setting this register to 0x1C (setting bits 4,3,and 2):
1) Send Low Byte of the Register (0x09)
• Command address write of address 0x3A
• Command data write of upper nibble of the Low Byte of
Register Address (0x00)
• Command data write of lower nibble of the Low Byte of
Register Address (0x09)
7.3
POLAR Register 0x04
This register controls the polarities of FIFO pin signals and the
WAKEUP pin.
POLAR
Bit #
Bit
Name
Read/W
rite
Default
7
WUPOL
R/W
0
6
0
R/W
0
5
4
3
2
1
EF
R/W
0
0x04
0
FF
R/W
0
PKTEND SLOE
R/W
0
R
0
SLRD SLWR
R
0
R
0
Document #: 38-08013 Rev. *E
Page 16 of 42
CYPRESS [ CYPRESS SEMICONDUCTOR ]
