
EZ-USB FX2 Technical Reference Manual
Page 15-16 EZ-USB FX2 Technical Reference Manual v2.1
Bit 3 ASYNC FIFO/GPIF Asynchronous Mode
When ASYNC=0, the FIFO/GPIF operate synchronously: a clock is supplied either internally
or externally on the IFCLK pin; the FIFO control signals function as read and write enable sig-
nals for the clock signal.
When ASYNC=1, the FIFO/GPIF operate asynchronously: no clock signal input to IFCLK is
required; the FIFO control signals function directly as read and write strobes.
Bit 2 GSTATE Drive GSTATE [2:0] on PORTE [2:0]
When GSTATE=1, three bits in Port E take on the signals shown in Table 15-6. The GSTATE
bits, which indicate GPIF states, are used for diagnostic purposes.
Bit 1-0 IFCFG1:0 Select Interface Mode (Ports, GPIF, or Slave FIFO)
These bits control the following FX2 interface signals, as shown in Tabl e15-8.
Table 15-6. Port E Alternate Functions When GSTATE=1
IO Pin Alternate Function
PE0 GSTATE[0]
PE1 GSTATE[1]
PE2 GSTATE[2]
Table 15-7. Ports, GPIF, Slave FIFO Select
IFCFG1 IFCFG0 Configuration
0 0 Ports
0 1 Reserved
1 0 GPIF Interface (internal
master)
1 1 Slave FIFO Interface
(external master)
Komentáře k této Příručce