
Chapter 15. Registers Page 15-51
15.7.7 USB Error Interrupt Enable/Request
Figure 15-49. USB Error Interrupt Enables
Figure 15-50. USB Error Interrupt Request
Bit 7-4 ISOEP[8,6,4,2] ISO Error Packet
The ISO EP Flag is set when:
• ISO OUT data PIDs arrive out of sequence (applies to high speed only).
• An ISO OUT packet was dropped because no buffer space was available for an OUT
packet (in either full- or high-speed modes).
Bit 0 ERRLIMIT Error Limit
ERRLIMIT counts USB bus errors—CRC, bit stuff, etc., and triggers the interrupt when the
programmed limit (0-15) is reached.
The firmware clears an interrupt request bit by writing a “1” to it. (See the following Note).
Do not clear an IRQ bit by reading an IRQ Register, ORing its contents with a bit mask, and writing
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.
USBERRIE USB Error Interrupt Enables (INT2) E662
b7 b6 b5 b4 b3 b2 b1 b0
ISOEP8 ISOEP6 ISOEP4 ISOEP2 0 0 0 ERRLIMIT
R/W R/W R/W R/W R/W R/W R/W R/W
0 0 0 0 0 0 0 0
USBERRIRQ USB Error Interrupt Request (INT2) E663
b7 b6 b5 b4 b3 b2 b1 b0
ISOEP8 ISOEP6 ISOEP4 ISOEP2 0 0 0 ERRLIMIT
R/W R/W R/W R/W R/W R/W R/W R/W
0 0 0 0 0 0 0 0
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