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Subject: USB On-The-Go (OTG) (was: Re: 2nd ATA Device on JB20 Recorder)
From: Francesco Grassi (
Date: 2003-01-23

Hi guys,
I found these links:
Point-to-Point Connectivity The OTG Supplement extends the USB standard to
enable point-to-point communication between two USB devices: one OTG device
and another OTG or traditional USB device. Because the two devices still
maintain the roles of host and peripheral, OTG point-to-point communication
is not to be confused with peer-to-peer. Unlike traditional USB, OTG allows
only one peripheral at a time to be connected to the device acting as host.
OTG devices do support USB hubs, a traditional way of enabling multiple USB
peripherals to share a single USB host connection. However, some OTG
functionality such as swapping host/peripheral roles and peripheral session
requests are not supported across today's USB hubs.

USB OTG device types range from battery-powered handheld products to
non-portable peripherals. While initial device roles (host/peripheral) are
defined by how they are cabled together, some OTG devices can switch roles
through the host negotiation protocol (HNP) without changing the cabling.

Figure 3: OTG enables point-to-point connectivity between peripherals
without a traditional PC host.

To better understand how new OTG devices and features add to existing USB
functionality, a quick review of USB device terminology follows.

The A-device is the default host at the start of a session. It supplies
power to VBUS.
The B-device is the default peripheral at the start of a session.
To these, the OTG Supplement adds the OTG device and defines two types: a
dual-role device and a peripheralonly device.

Maybe it could be useful for our objective...


-----Messaggio originale-----
Da: []Per
conto di roland
Inviato: mercoledý 22 gennaio 2003 23.35
Oggetto: Re: 2nd ATA Device on JB20 Recorder

otherwise CF2IDE Adapters like these:
would be a bit dangerous :)

First I was unsure about this because I read contradictory comments - but
at least approved that CF supports BOTH


----- Original Message -----
From: "Stuart Tedford" <>
To: <>
Sent: Wednesday, January 22, 2003 5:29 PM
Subject: RE: 2nd ATA Device on JB20 Recorder

> >-----Original Message-----
> >From: Andrew Jamieson
> >
> >And dont forget that CF cards use 3.3V power, not 5V.
> No, CF cards allow for both 3.3 and 5V supply.
> Stu.

Page was last modified "Jan 10 2012" The Rockbox Crew