PHY-less ULPI and UTMI bridges
Embodiments of the present invention provide a unique capability of implementing a pair of pseudo-PHY interfaces using a bridge. From the host and device perspectives, the host and device communicate through a PHY interface. The bridge, however, avoids actually using a USB PHY interface. This PHY-less bridge allows communication between a host and a device at high speeds without high-power transceivers associated with a USB PHY interface. In accordance with the present invention, a host and a device may be coupled together using a PHY-less bridge using the same interface or translating between different interfaces by using a wrapper. Such PHY-less bridges include a UTMI-to-UTMI bridge, a UTMI-to-ULPI bridge, a ULPI-to-UTMI bridge and a ULPI-to-ULPI bridge, each avoiding the need for a USB PHY interface.
1. A programmable logic device comprising:
a bridge to operate between a first USB (Universal Serial Bus) unit and a second USB unit, wherein the bridge is configurable to emulate a physical layer between the first USB unit and the second USB unit;
programmable logic;
a first physical interface coupled, via the programmable logic, to the first USB unit and to the bridge; and
a second physical interface coupled, via the programmable logic, to the second USB unit and to the bridge.
2. The programmable logic device of claim 1 , wherein:
the first USB unit comprises a USB host; and
the second USB unit comprises a USB device.
3. The programmable logic device of claim 1 , wherein:
the first USB unit comprises a first OTG (On-The-Go) USB device; and
the second USB unit comprises a second OTG USB device.
4. The programmable logic device of claim 1 , wherein the bridge for UTMI (Universal Transceiver Macrocell Interface) comprises a UTMI-to-UTMI host/device bridge.
5. The programmable logic device of claim 1 , wherein the bridge for UTMI (Universal Transceiver Macrocell Interface) comprises a UTMI-to-UTMI OTG (On-The-Go) bridge.
6. The programmable logic device of claim 1 , wherein the bridge for ULPI (UTMI (Universal Transceiver Macrocell Interface)+Low Pin Interface) comprises a ULPI-to-ULPI bridge without a wrapper.
7. The programmable logic device of claim 1 , wherein the bridge for ULPI (UTMI (Universal Transceiver Macrocell Interface)+Low Pin Interface) comprises a ULPI-to-ULPI bridge comprising:
a first interface controller;
a second interface controller coupled to the first interface controller through a physical interface;
host ULPI PHY (physical layer) registers coupled to the first interface controller; and
device ULPI PHY registers coupled to the second interface controller.
8. The programmable logic device of claim 7 , wherein the physical interface between the first interface controller and the second interface controller comprise two eight-bit data buses.
9. The programmable logic device of claim 1 , wherein:
the first physical interface comprises circuitry to operate with a first set of ULPI (UTMI (Universal Transceiver Macrocell Interface)+Low Pin Interface) interface signals; and
the second physical interface comprises circuitry to operate with a second set of ULPI interface signals; and
each of the first and second set of ULPI interface signals comprises
a stop signal;
a direction signal;
a next signal;
data signals; and
a clock signal.
10. The programmable logic device of claim 1 , further comprising a ULPI-UTMI wrapper comprising:
a ULPI (UTMI+Low Pin Interface) upstream wrapper;
host ULPI PHY (physical layer) registers coupled to the ULPI upstream wrapper;
UTMI (Universal Transceiver Macrocell Interface) interface signals coupled to the bridge; and
ULPI interface signals coupled to the first USB unit.
11. The programmable logic device of claim 1 , further comprising a ULPI-UTMI wrapper comprising:
a ULPI (UTMI+Low Pin Interface) downstream wrapper;
device ULPI PHY (physical layer) registers coupled to the ULPI downstream wrapper;
UTMI (Universal Transceiver Macrocell Interface) interface signals coupled to the bridge; and
ULPI interface signals coupled to the first USB unit.
12. The programmable logic device of claim 11 , wherein the ULPI-UTMI wrapper comprises at least one state machine to drive a ULPI signal protocol for handling UTMI signals.
13. A programmable logic device comprising:
bridging means for
operating between a first USB (Universal Serial Bus) unit and a second USB unit; and
emulating a physical layer between the first USB unit and the second USB unit;
programmable logic means for coupling circuitry together;
a first interface means for coupling, via the programmable logic means, to the first USB unit and to the bridge; and
a second interface means for coupling, via the programmable logic means, to the second USB unit and to the bridge.
14. The programmable logic device of claim 13 , wherein the bridging means comprises a bridging means for coupling UTMI (Universal Transceiver Macrocell Interface) interface signals from the first USB unit to UTMI interface signals from the second USB unit.
15. The programmable logic device of claim 13 , further comprising a means for coupling the bridge to a wrapper.
16. A method in a programmable logic device, the method comprising:
providing a bridge,
providing programmable logic;
providing a first USB (Universal Serial Bus) unit;
providing a second USB unit;
programming the programmable logic to electrically couple the first USB unit to the bridge; and
programming the programmable logic to electrically couple the second USB unit to the bridge;
wherein the bridge is configurable to emulate a physical layer between the first USB unit and the second USB unit.
17. The method of claim 16 , further comprising:
emulating a USB PHY (physical layer) interface signals between the first USB unit and the second USB unit using UTMI (Universal Transceiver Macrocell Interface) interface signals to the first USB unit.
18. The method of claim 16 , further comprising:
emulating a USB PHY (physical layer) interface signals between the first USB unit and the second USB unit using ULPI (UTMI (Universal Transceiver Macrocell Interface)+Low Pin Interface) interface signals to the first USB unit.
19. The method of claim 16 , wherein the acts of programming comprise emulating a physical layer between the first USB unit and the second USB unit.