CY7C68013
Document #: 38-08012 Rev. *A
Page 10 of 48
3.7.3
FIFO/GPIF Interrupt (INT4)
Just as the USB Interrupt is shared among 27 individual USB-interrupt sources, the FIFO/GPIF interrupt is shared among 14
individual FIFO/GPIF sources. The FIFO/GPIF Interrupt, like the USB Interrupt, can employ autovectoring. Table 3-3 shows the
priority and INT4VEC values for the 14 FIFO/GPIF interrupt sources
If Autovectoring is enabled (AV4EN = 1 in the INTSETUP register), the FX2 substitutes its INT4VEC byte. Therefore, if the high
byte (“page”) of a jump-table address is preloaded at location 0x0054, the automatically-inserted INT4VEC byte at 0x0055 will
direct the jump to the correct address out of the 14 addresses within the page. When the ISR occurs, the FX2 pushes the program
counter onto its stack then jumps to address 0x0053, where it expects to find a “jump” instruction to the ISR Interrupt service
routine.
3.8
Reset and Wakeup
3.8.1
Reset Pin
An input pin (RESET#) resets the chip. This pin has hysteresis and is active LOW. The internal PLL stabilizes approximately 200
µ
s after V
CC
has reached 3.3V. Typically, an external RC network (R = 100k, C = 0.1
µ
F) is used to provide the RESET# signal.
3.8.2
Wakeup Pins
The 8051 puts itself and the rest of the chip into a power-down mode by setting PCON.0 = 1. This stops the oscillator and PLL.
When WAKEUP is asserted by external logic, the oscillator restarts and after the PLL stabilizes, and the 8051 receives a wakeup
interrupt. This applies whether or not FX2 is connected to the USB.
The FX2 exits the power down (USB suspend) state using one of the following methods:
• USB bus signals resume
• External logic asserts the WAKEUP pin
• External logic asserts the PA3/WU2 pin.
The second wakeup pin, WU2, can also be configured as a general purpose I/O pin. This allows a simple external R-C network
to be used as a periodic wakeup source.
3.9
Program/Data RAM
3.9.1
Size
The FX2 has eight kbytes of internal program/data RAM, where PSEN#/RD# signals are internally ORed to allow the 8051 to
access it as both program and data memory. No USB control registers appear in this space.
Two memory maps are shown in the following diagrams:
Figure 3-1 Internal Code Memory, EA = 0
Figure 3-2 External Code Memory, EA = 1.
Table 3-3. Individual FIFO/GPIF Interrupt Sources
Priority
INT4VEC Value
Source
Notes
1
80
EP2PF
Endpoint 2 Programmable Flag
2
84
EP4PF
Endpoint 4 Programmable Flag
3
88
EP6PF
Endpoint 6 Programmable Flag
4
8C
EP8PF
Endpoint 8 Programmable Flag
5
90
EP2EF
Endpoint 2 Empty Flag
6
94
EP4EF
Endpoint 4 Empty Flag
7
98
EP6EF
Endpoint 6 Empty Flag
8
9C
EP8EF
Endpoint 8 Empty Flag
9
A0
EP2FF
Endpoint 2 Full Flag
10
A4
EP4FF
Endpoint 4 Full Flag
11
A8
EP6FF
Endpoint 6 Full Flag
12
AC
EP8FF
Endpoint 8 Full Flag
13
B0
GPIFDONE
GPIF Operation Complete
14
B4
GPIFWF
GPIF Waveform
