On Mon, 14 Jul 2014, Grant wrote:
I should have been more specific then. I think I understand, but to
be sure, if I splice a USB cable, power VBUS with an external 5V power
supply, and connect a host and device, the device will work as if the
cable was connected to the host normally?
You are right, the device will get 5 volts. However it is still part
of the spec that 2ms without a SOF will force the device into suspend
mode, so it will use less than 2ma. So depending on your definition of
function, there will be power, but no activity. If it uses more than
2ma, from
On Mon, 14 Jul 2014, Grant wrote:
You are right, the device will get 5 volts. However it is still part
of the spec that 2ms without a SOF will force the device into suspend
mode, so it will use less than 2ma. So depending on your definition of
function, there will be power, but no
I should have been more specific then. I think I understand, but to
be sure, if I splice a USB cable, power VBUS with an external 5V power
supply, and connect a host and device, the device will work as if the
cable was connected to the host normally?
Yes. But why do you want to do
On Mon, 7 Jul 2014, Steve Calfee wrote:
You are right, the device will get 5 volts. However it is still part
of the spec that 2ms without a SOF will force the device into suspend
mode, so it will use less than 2ma. So depending on your definition of
function, there will be power, but no
You are right, the device will get 5 volts. However it is still part
of the spec that 2ms without a SOF will force the device into suspend
mode, so it will use less than 2ma. So depending on your definition of
function, there will be power, but no activity. If it uses more than
2ma, from the
On Tue, 8 Jul 2014, Grant wrote:
You are right, the device will get 5 volts. However it is still part
of the spec that 2ms without a SOF will force the device into suspend
mode, so it will use less than 2ma. So depending on your definition of
function, there will be power, but no
it isn't possible to disable Vbus on a USB host port and still use the
port. To do what you want, you would have to physically cut the Vbus
wire in the USB cable and splice the device side of that wire to the
external power supply.
I think I'll try that. Can anyone confirm that it should
, problems will ensue.
Steve
On Mon, Jul 7, 2014 at 6:00 PM, Grant emailgr...@gmail.com wrote:
it isn't possible to disable Vbus on a USB host port and still use the
port. To do what you want, you would have to physically cut the Vbus
wire in the USB cable and splice the device side of that wire
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when
Grant emailgr...@gmail.com writes:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when
On Tue, 10 Jun 2014, Grant wrote:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY
The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when the session is valid (VBUS 4.4V).
Hmmm that might be the cause of some 'random' USB disconnects
we were seeing.
We 'fixed' them by cutting the wire in the usb cable and
The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when the session is valid (VBUS 4.4V).
Hmmm that might be the cause of some 'random' USB disconnects
we were seeing.
We 'fixed' them by cutting the wire in the usb cable
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know
On Tue, 10 Jun 2014, Grant wrote:
Understood. Can you tell me how to disable VBUS on the USB
hub/controller? I'll be attempting this on a Beaglebone.
I don't know what controller the Beaglebone uses. In general, however,
it isn't possible to disable Vbus on a USB host port and still
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when
On Sat, 7 Jun 2014, Grant wrote:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
samples VBUS levels to know when
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
Can you please elaborate the question of why VBus should go off ? Is this
question in the context of any new USB specification ?
It's not related to a USB spec, it's just part
On Wed, 14 May 2014, Grant wrote:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus, the PHY still
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
- Grant
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Hi,
On Tue, May 13, 2014 at 05:34:31PM -0700, Grant wrote:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
unfortunately not, your device would see a disconnection. The reason is
that even though you don't really put any load on the bus
On Wed, May 14, 2014 at 6:04 AM, Grant emailgr...@gmail.com wrote:
Can I disable VBUS while keeping the rest of USB functional for a
device that does not require bus power?
Can you please elaborate the question of why VBus should go off ? Is
this question in the context of any new USB
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