Siemens S50037 manual USB Interface, Disconnect and Resume Signalling, Power Modes, Usbresume

USB Interface

Overview

￿12Mbits/s bit rate

￿BC01 operates as a peripheral USB device

￿Two modes, bus powered and self powered

￿Careful product design is required for product to remain USB1.1 compliant

￿4 USB lines are required

￿Minimum voltage on VCC_IO terminal is 3.0V for USB operation

The SieMo contains its own full-speed (12Mbits/s) USB interface. To get a product USB 1.1 certified, please visit www.usb.org for further information. The voltage on Vcc-IO must be between 3.0 and 3.4 V for USB operation. It is possible to connect the Vcc-IO to the Vreg output of the module, which provides a regulated voltage of 3.15V.

Although SieMo is capable of meeting the USB 1.1 specification, Siemens cannot guarantee that an application circuit designed around the IC is USB compliant. The choice of application circuit, component choice and PCB layout all affect USB signal quality and electrical characteristics. The information in this document is intended as a guide and should be read in association with the USB 1.1 specification, with particular attention being given to Chapter 7. Independent USB qualification must be sought before an application is deemed USB compliant and can bear the USB logo. Such qualification can be obtained from a USB plugfest or from an independent USB test house.

SieMo S50037 Data Book PRELIMINARILY

Disconnect and Resume Signalling

SieMo provides some signalling lines for USB operation. These functions are disabled by default but can be activated via firmware settings.

The USB_DETACH and USB_WAKE_UP terminals provide extra signalling alongside the normal USB data lines. They are not part of the USB specification and full USB functionality can be attained without their use. The Disconnect message may be useful on its own, but it is hard to see an application for USB_RESUME in isolation. USB_DETACH (Disconnect Signalling) USB_DETACH is an input, when asserted high, causes SieMo to put USB_PULL_UP, USB_D- and USB_D+ in

ahigh-impedance state. This detaches the device from the bus and is logically equivalent to unplugging the module. When USB_DETACH is taken low, SieMo will connect back to USB and await enumeration by the USB host.

USB_RESUME

USB_WAKE_UP is an active high output used only when USB_DETACH is active to wake-up the host and allow USB communication to recommence. It replaces the function of the USB Resume message, which cannot be sent while SieMo is effectively disconnected from the bus.

Power Modes

SieMo is by default set to be powered from the Bus. It can be set to a self powered Device by changing firmware settings. In this case the USB_ON must be connected to the Vbus line via a 47k/22k

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