CY7C68013
Table 3-1. Special Function Registers
x
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
8x
IOA
SP
DPL0
DPH0
DPL1
DPH1
DPS
PCON
TCON
TMOD
TL0
TL1
TH0
TH1
CKCON
SCON0
SBUF0
AUTOPTRH1
AUTOPTRL1
reserved
AUTOPTRH2
AUTOPTRL2
reserved
AUTOPTRSETUP
EP2468STAT
EP24FIFOFLGS
EP68FIFOFLGS
GPIFSGLDATH
GPIFSGLDATLX
GPIFSGLDATLNOX
EP01STAT
GPIFTRIG
RCAP2L
RCAP2H
TL2
TH2
IE
IP
T2CON
EICON
EIE
EIP
9x
IOB
EXIF
MPAGE
Ax
IOC
INT2CLR
INT4CLR
Bx
IOD
IOE
OEA
OEB
OEC
OED
OEE
Cx
SCON1
SBUF1
Dx
PSW
Ex
ACC
Fx
B
3.5
USB Boot Methods
During the power-up sequence, internal logic checks the I
2
C-compatible port for the connection of an EEPROM whose first byte
is either 0xC0 or 0xC2. If found, it uses the VID/PID/DID values in the EEPROM in place of the internally stored values (0xC0),
or it boot-loads the EEPROM contents into internal RAM (0xC2). If no EEPROM is detected, FX2 enumerates using internally
stored descriptors. The default ID values for FX2 are VID/PID/DID (0x04B4, 0x8613, 0xxxyy).
Table 3-2. Default ID Values for FX2
Default VID/PID/DID
Vendor ID
Prod ID
Device release
0x04B4
0x8613
0xXXYY
Cypress Semiconductor
EZ-USB FX2
Depends on revision (0x04 for Rev E)
Note.
The I
2
C-compatible bus SCL and SDA pins must be pulled up, even if an EEPROM is not connected. Otherwise this
detection method does not work properly.
3.6
ReNumeration
™
Because the FX2’s configuration is soft, one chip can take on the identities of multiple distinct USB devices.
When first plugged into USB, the FX2 enumerates automatically and downloads firmware and USB descriptor tables over the
USB cable. Next, the FX2 enumerates again, this time as a device defined by the downloaded information. This patented two-
step process, called ReNumeration
™
, happens instantly when the device is plugged in, with no hint that the initial download step
has occurred.
Two control bits in the USBCS (USB Control and Status) register control the ReNumeration process: DISCON and RENUM. To
simulate a USB disconnect, the firmware sets DISCON to 1. To reconnect, the firmware clears DISCON to 0.
Before reconnecting, the firmware sets or clears the RENUM bit to indicate whether the firmware or the Default USB Device will
handle device requests over endpoint zero: if RENUM = 0, the Default USB Device will handle device requests; if RENUM = 1,
the firmware will.
3.7
Bus Powered Applications
Bus powered applications require the FX2 to enumerate in a unconfigured mode with less then 100 mA. To do this, the FX2 must
enumerate in the full speed mode and then, when configured, renumerate in high speed mode. For an example of the benefits
and limitations of this renumeration process see the application note titled “Bus Powered Enumeration with FX2”.
Document #: 38-08012 Rev. *C
Page 9 of 52
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