
EZ-USB FX2 Technical Reference Manual
Page 15-48 EZ-USB FX2 Technical Reference Manual v2.1
Bit 5 HSGRANT Grant High Speed Access
The FX2 SIE sets this bit when it has been granted high speed (480 Mbits/sec) access to
USB.
Bit 4 URES USB Reset Interrupt Request
The USB signals a bus reset by driving both D+ and D- low for at least 10 milliseconds. When
the USB core detects the onset of USB bus reset, it activates the URES Interrupt Request.
The USB core sets this bit to “1” when it detects a USB bus reset. Write a “1” to this bit to clear
the interrupt request.
Bit 3 SUSP Suspend Interrupt Request
If the EZ-USB FX2 detects 3 ms of no bus activity, it activates the SUSP (Suspend) Interrupt
Request. The USB core sets this bit to “1” when it detects USB SUSPEND signaling (no bus
activity for 3 ms). Write a “1” to this bit to clear the interrupt request.
Bit 2 SUTOK Setup Token
The USB core sets this bit to “1” when it receives a SETUP token. Write a “1” to this bit to clear
the interrupt request.
Bit 1 SOF Start of Frame
The USB core sets this bit to “1” when it receives a SOF packet. Write a “1” to this bit to clear
the interrupt request.
Bit 0 SUDAV SETUP Data Available Interrupt Request
The USB core sets this bit to “1” when it has transferred the eight data bytes from an endpoint
zero SETUP packet into internal registers (at SETUPDAT). Write a “1” to this bit to clear the
interrupt request.
Do not clear an IRQ bit by reading an IRQ Register, ORing its contents with a bit mask, and writ-
ing back the IRQ Register. This will clear ALL pending interrupts. Instead, simply write the bit mask
value (with a “1” in the bit position of the IRQ you want to clear) directly to the IRQ Register.
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