AN2131-DK001 Cypress Semiconductor Corp, AN2131-DK001 Datasheet - Page 177

• Manufacturer Part Number: AN2131-DK001
• Description: KIT EZ-USB DEVELOPMENT BOARD
• Manufacturer: Cypress Semiconductor Corp

Specifications of AN2131-DK001

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 428-1333

In some situations, the host may send IN tokens before the 8051 has loaded and armed an
IN endpoint. To alert the 8051 that an IN endpoint is being pinged, the AN2122/26 add a
set of interrupts, one per IN endpoint, that indicate that an IN endpoint just sent a NAK to
the host. This happens when the host sends an IN token and the IN endpoint does not have
data (yet) for the host.
The new interrupt is called “IBN,” for IN Bulk NAK. Its INT2 Autovector is 05, which
was previously reserved in the EZ-USB family.
The IBN interrupt requests and enables are controlled by two new registers. Note that
because the IBN interrupt exists only in the AN2122/AN2126, which has 6 bulk IN end-
points, there are IRQ and IEN bits endpoints IN0 through IN6.
Each of the individual IN endpoints may be enabled for an IBN interrupt using the IBNEN
register. The 8051 sets an interrupt enable bit to “1” to enable the corresponding interrupt.
The ISR tests the IBNIRQ bits to determine which endpoint or endpoints generated the
interrupt request. As with all other EZ-USB interrupt requests, the 8051 clears an
IBNIRQ bit by writing a “1” to it.
Page 9-14
IBNIRQ
IBNEN
R/W
R/W
b7
b7
x
x
-
-
EP6IN
EP6IN
R/W
R/W
b6
b6
x
0
Figure 9-10. IN Bulk NAK Interrupt Enable Register
Figure 9-9. IN Bulk NAK Interrupt Request Register
EP5IN
EP5IN
R/W
R/W
IN Bulk NAK Interrupt Requests
b5
b5
x
IN Bulk NAK Interrupt Enables
0
Chapter 9. EZ-USB Interrupts
EP4IN
EP4IN
R/W
R/W
b4
b4
x
0
EP3IN
EP3IN
R/W
R/W
b3
b3
x
0
EP2IN
EP2IN
R/W
R/W
b2
b2
x
0
EP1IN
EP1IN
R/W
R/W
b1
b1
x
0
EZ-USB TRM v1.9
EP0IN
EP0IN
R/W
R/W
b0
b0
x
0
7FB0
7FB1