Rockbox mail archive
Subject: Re: USB On-The-Go (OTG) (was: Re: 2nd ATA Device on JB20 Recorder)
From: Joaquim Carvalho (jdc_at_x64.com)
We must check:
- if there are physical limitations on the USB chips
ie - no way to power the VBUS, etc.
- ways to solve these limitations
A simple 50cents smd transistor controlled by the H1
would solve this.
- How much of the USB control can be done in software
Most hackers will find this quite an interesting job,
most programmers would hate.
On Wed, 2003-01-22 at 23:49, Andrew Jamieson wrote:
> USB OTG requires special controllers, and is not supported by either of the
> USB chips Archos uses.
> Andrew Jamieson
> ----- Original Message -----
> From: "Francesco Grassi" <frangras_at_tin.it>
> To: <rockbox_at_cool.haxx.se>
> Sent: Thursday, January 23, 2003 10:25 AM
> Subject: USB On-The-Go (OTG) (was: Re: 2nd ATA Device on JB20 Recorder)
> > Hi guys,
> > I found these links:
> > http://www.semiconductors.philips.com/buses/usb/products/otg/
> > html
> > [...]
> > Point-to-Point Connectivity The OTG Supplement extends the USB standard to
> > enable point-to-point communication between two USB devices: one OTG
> > and another OTG or traditional USB device. Because the two devices still
> > maintain the roles of host and peripheral, OTG point-to-point
> > is not to be confused with peer-to-peer. Unlike traditional USB, OTG
> > only one peripheral at a time to be connected to the device acting as
> > OTG devices do support USB hubs, a traditional way of enabling multiple
> > peripherals to share a single USB host connection. However, some OTG
> > functionality such as swapping host/peripheral roles and peripheral
> > 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.
> > [...]
> > http://www.usb.org/developers/onthego/
> > Maybe it could be useful for our objective...
> > FG
> > -----Messaggio originale-----
> > Da: owner-rockbox_at_cool.haxx.se [mailto:owner-rockbox_at_cool.haxx.se]Per
> > conto di roland
> > Inviato: mercoledý 22 gennaio 2003 23.35
> > A: rockbox_at_cool.haxx.se
> > Oggetto: Re: 2nd ATA Device on JB20 Recorder
> > jep,
> > otherwise CF2IDE Adapters like these:
> > ory+Disk+Drives
> > would be a bit dangerous :)
> > First I was unsure about this because I read contradictory comments - but
> > at least
> > http://www.compactflash.org/faqs/faq.htm#dvs approved that CF supports
> > voltages.
> > Regards
> > Roland
> > ----- Original Message -----
> > From: "Stuart Tedford" <stuart.tedford_at_piresearch.co.uk>
> > To: <rockbox_at_cool.haxx.se>
> > 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