CY7C68300C, CY7C68301C
CY7C68320C, CY7C68321C
Document 001-05809 Rev. *C
Page 13 of 41
SYSIRQ
The SYSIRQ pin provides a way for systems to request service
from host software by using the USB Interrupt pipe on endpoint
1 (EP1). If the AT2LP has no pending interrupt data to return,
USB interrupt pipe data requests are NAKed. If pending data is
available, the AT2LP returns 16 bits of data. This data indicates
whether AT2LP is operating in high speed or full speed, whether
the AT2LP is reporting self-powered or bus-powered operation,
and the states of any GPIO pins that are configured as inputs.
GPIO pins can be individually set as inputs or outputs, with byte
0x09 of the configuration data. The state of any GPIO pin that is
not set as an input is reported as ‘0’ in the EP1 data.
Table 3 gives the bitmap for the data returned on the interrupt
pipe and Figure 8 depicts the latching algorithm incorporated by
the AT2LP.
The SYSIRQ pin must be pulled LOW if HID functionality is used.
Refer to “HID Functions for Button Controls” on page 15 for more
details on HID functionality.
Figure 8. SYSIRQ Latching Algorithm
Table 3. Interrupt Data Bitmap
EP1 Data Byte 1
EP1 Data Byte 0
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
USB Interrupt
Pipe Polled?
Yes
No
NAK Request
SYSIRQ=1?
Latch State of IO Pins
Set Int_Data = 1
Int_Data = 1?
No
Return Interrupt Data
Set Int_Data = 0
Yes
Yes
No
Yes
Int_Data = 0
and
SYSIRQ=0?
No
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