AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 114

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Detach Simulation
114
AT8xC5122/23
In order to be re-enumerated by the Host, the AT8xC5122/23 has the possibility to sim-
ulate a DETACH-ATTACH of the USB bus.
The V
D+ pull-up as shown in Figure 61. This output can be put in high-impedance when the
DETACH bit is set to 1 in the USBCON register. Maintaining this output in high imped-
ance for more than 3 µs will simulate the disconnection of the device. When resetting
the DETACH bit, an ATTACH is then simulated. The USB controller should be enabled
to use this feature.
Figure 61. Example of V
Figure 62. Disconnect Timing
V
IHZ(min)
V
V
REF
SS
IL
output voltage is between 3.0V and 3.6V. This output can be connected to the
D+
D-
V
Disconnected
REF
D-
D+
Device
REF
R2
R3
Connection
R1
>= 2,5 µs
1
2
3
4
USB-B Connector
VCC
D-
D+
GND
Disconnect
Detected
4202D–SCR–06/05