USB2640 datasheet(42/60 Pages) MICROCHIP

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USB2640/USB2641

DS00001947C-page 42

 2015-2021 Microchip Technology Inc.

7.5.2.1

nRESET for EEPROM Configuration

7.5.3

USB BUS RESET

In response to the upstream port signaling a reset to the device, the device does the following:

Sets default address to ‘0’.

Sets configuration to: Unconfigured.

Negates PRTCTL[3:2] to all downstream ports.

Clears all TT buffers.

Moves device from suspended to active (if suspended).

Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the reset sequence.

The host then configures the device and the device’s downstream port devices in accordance with the USB 2.0 Speci-

fication.

FIGURE 7-1:

NRESET TIMING FOR EEPROM MODE

TABLE 7-6:

NRESET TIMING FOR EEPROM MODE

Name

Description

MIN

TYP

MAX

Units

nRESET asserted.

sec

Device recovery/stabilization.

500

sec

8051 programs device configuration

msec

USB attach (See Note).

100

msec

Host acknowledges attach and signals USB reset.

100

msec

USB idle.

Undefined

msec

Completion time for requests (with or without data

stage).

msec

Note:

All power supplies must have reached the operating levels mandated in Section 9.0, "DC Parameters," on

page 47, prior to (or coincident with) the assertion of nRESET.

Note:

The device does not propagate the upstream USB reset to downstream devices.

nRESET

VSS

Hardware

reset

asserted

Device

Recovery/

Stabilization

8051 Sets

Configuration

Registers

Attach

USB

Upstream

USB Reset

recovery

Idle

Start

completion

request

response

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