AT90USB646 datasheet(252/434 Pages) ATMEL

252 / 434 page

252

7593A–AVR–02/06

AT90USB64/128

• The ID bit is cleared by hardware when a low level has been detected on the ID pin. The

Device controller is then disabled and the Host controller enabled.

The software anyway has to select the mode (Host, Device) in order to access to the Device

controller registers or to the Host controller registers, which are multiplexed. For example, even

if the USB controller has detected a Device mode (pin ID high), the software shall select the

device mode (bit HOST cleared), otherwise it will access to the host registers. This is also true

for the Host mode.

21.4.2

Power-on and reset

The next diagram explains the USB controller main states on power-on:

Figure 21-9. USB controller states after reset

USB Controller state after an hardware reset is ‘Reset’. In this state:

• USBE is not set

• the macro clock is stopped in order to minimize the power consumption (FRZCLK=1),

• the macro is disabled,

• the pad is in the suspend mode,

• the Host and Device USB controllers internal states are reset.

• The DPACC bit and the DPADD10:0 field can be set by software. The DPRAM is not cleared.

• The SPDCONF bits can be set by software.

After setting USBE, the USB Controller enters in the Host or in the Device state (according to the

IP pin). The selected controller is ‘Idle’.

The USB Controller can at any time be ‘stopped’ by clearing USBE. In fact, clearing USBE acts

as an hardware reset.

21.4.3

Interrupts

Two interrupts vectors are assigned to USB interface.

Dev ice

Reset

USBE=0

<anyother

state>

USBE=1

ID=1

Clockstopped

FRZCLK=1

Macrooff

USBE=0

Host

USBE=0

RESET

USBE=1

ID=0

AT90USB646 Datasheet(PDF) 252 Page - ATMEL Corporation

AT90USB646 Datasheet(HTML) 252 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL