Rainbow-electronics AT89C5122 Manual do Utilizador descarregar pdf (Página 114)

114

AT8xC5122/23

4202E–SCR–06/06

Detach Simulation 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

REF

output voltage is between 3.0V and 3.6V. This output can be connected to the

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

REF

Connection

Figure 62. Disconnect Timing

D-

D+

D-

D+

GND

VCC

REF

USB-B Connector

D+

D-

IHZ(min)

Device

Disconnected

Disconnect

Detected

>= 2,5 μs

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Rainbow-electronics AT89C5122 Manual do Utilizador Página 114