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PC support for low speed USB (1.5Mbps)

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Eugen_E

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According to the USB standard, a full speed USB host (12Mbps) should support full speed (12Mbps) and low speed (1.5Mbps) devices. A high speed USB host (480Mbps) should support high speed and full speed, but not necessary low speed.

I want to ask what is your experience in connecting low speed devices to modern PCs with high speed USB.
I want to design a low speed USB device based on AVR uC (app note AVR309, and other sources) and want to know if I will have problems in connecting it to some PCs. If there isn't support for low speed anymore I will use FT232 for USB/RS232 conversion.

Thanks.
 

krejca85

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    Eugen_E

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potyo

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From Chapter 7 of USB Specification

A USB 2.0 downstream facing transceiver must support high-speed, full-speed, and low-speed modes.
 

    Eugen_E

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kanagavel_docs

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Hi,

If you one the device details in modern PCs you will find two major host controller.
UHCI - Supported for Full/low speed
EHCI - for High speed alone
Depend on the speed settling the data will be routed to the host.

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Eugen_E

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Thanks for the replies. I will use low speed USB on AVR according to AVR309 appnote.
 

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