CY7C68013
Document #: 38-08012 Rev. *E
Page 3 of 48
3.3
I2C-compatible Bus
FX2 supports the I2C-compatible bus as a master only at
100/400 kbps. SCL and SDA pins have open-drain outputs
and hysteresis inputs. These signals must be pulled up to
3.3V, even if no I2C-compatible device is connected.
3.4
Buses
All packages: 8- or 16-bit “FIFO” bidirectional data bus, multi-
plexed on I/O ports B and D. 128-pin package: adds 16-bit
output-only 8051 address bus, 8-bit bidirectional data bus.
3.5
USB Boot Methods
During the power-up sequence, internal logic checks the I2C-
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).
Note. The I2C-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 automati-
cally 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”.
Table 3-1. Special Function Registers
x8x
9x
Ax
Bx
Cx
Dx
Ex
Fx
0
IOA
IOB
IOC
IOD
SCON1
PSW
ACC
B
1SP
EXIF
INT2CLR
IOE
SBUF1
2DPL0
MPAGE
INT4CLR
OEA
3DPH0
OEB
4
DPL1
OEC
5
DPH1
OED
6
DPS
OEE
7PCON
8
TCON
SCON0
IE
IP
T2CON
EICON
EIE
EIP
9
TMOD
SBUF0
ATL0
AUTOPTRH1
EP2468STAT
EP01STAT
RCAP2L
BTL1
AUTOPTRL1
EP24FIFOFLGS
GPIFTRIG
RCAP2H
CTH0
reserved
EP68FIFOFLGS
TL2
DTH1
AUTOPTRH2
GPIFSGLDATH
TH2
E
CKCON
AUTOPTRL2
GPIFSGLDATLX
F
reserved
AUTOPTRSETUP
GPIFSGLDATLNOX
Table 3-2. Default ID Values for FX2
Default VID/PID/DID
Vendor ID
0x04B4
Cypress Semiconductor
Prod ID
0x8613
EZ-USB FX2
Device release
0xXXYY
Depends on revision
(0x04 for Rev E)
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