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CY7C65640A Datasheet(PDF) 4 Page - Cypress Semiconductor |
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CY7C65640A Datasheet(HTML) 4 Page - Cypress Semiconductor |
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4 / 25 page  CY7C65640A Document Number: 38-08019 Rev. *N Page 4 of 25 Functional Overview The Cypress TetraHub USB 2.0 hub is a high performance, low-system-cost solution for USB. This hub integrates 1.5k upstream pull up resistors for full speed operation and all downstream 15k pull down resistors and series termination resistors on all upstream and downstream D+ and D– pins. This results in optimization of system costs by providing built-in support for the USB 2.0 specification. System Initialization On power up, the TetraHub reads an external SPI EEPROM for configuration information. At the most basic level, this EEPROM has the Vendor ID (VID), Product ID (PID), and Device ID (DID) for the customer’s application. For more specialized applications, other configuration options can be specified. See Configuration Options on page 12 for more details. After reading the EEPROM, if BUSPOWER (connected to the upstream VBus) is high, TetraHub enables the pull up resistor on the D+ to indicate that it is connected to the upstream hub, after which a USB bus reset is expected. During this reset, TetraHub initiates a chirp to indicate that it is a high speed peripheral. In a USB 2.0 system, the upstream hub responds with a chirp sequence, and TetraHub is in a high speed mode, with the upstream D+ pull up resistor turned off. In USB 1.x systems, no such chirp sequence from the upstream hub is seen, and TetraHub operates as a normal 1.x hub (operating at full speed). Enumeration After a USB Bus Reset, TetraHub is in an unaddressed, unconfigured state (configuration value set to 0). During the enumeration process, the host sets the hub’s address and configuration by sending a SetCongfiguration request. Changing the hub address restores it to an unconfigured state. For high speed multi-TT support, the host must also set the alternate interface setting to 1 (the default mode is single TT). After the hub is configured, the full hub functionality is available. Multiple Transaction Translator Support After TetraHub is configured in a high speed system, it is in single TT mode. The host may then set the hub into multiple TT mode by sending a SetInterface command. In multiple TT mode, each full speed port is handled independently and thus has a full 12 Mbps bandwidth available. In Single TT mode, all traffic from the host destined for full or low speed ports are forwarded to all of those ports. This means that the 12 Mbps bandwidth is shared by all full and low speed ports. Downstream Ports TetraHub supports a maximum of four downstream ports, each of which may be marked as usable or removable in the extended configuration (0xD2 EEPROM load, see section). Downstream D+ and D– pull down resistors are incorporated in TetraHub for each port. Prior to the hub being configured, the ports are driven SE0 (Single Ended Zero, where both D+ and D– are driven low) and are set to the unpowered state. After the hub is configured, the ports are not driven, and the host may power the ports by sending a SetPortPower command to each port. After a port is powered, any connect or disconnect event is detected by the hub. Any change in the port state is reported by the hub back to the host through the Status Change Endpoint (endpoint 1). Upon receipt of SetPortReset command from the host, the hub does the following: ■ Drive SE0 on the corresponding port ■ Put the port in an enabled state ■ Enable the green port indicator for that port (if not previously overridden by the host) ■ Enable babble detection after the port is enabled. Babble consists of either unterminated traffic from a downstream port (or loss of activity), or a non-idle condition on the port after EOF2. If babble is detected on an enabled port, that port is disabled. A ClearPortEnable command from the host also disables the specified port. Downstream ports can be individually suspended by the host with the SetPortSuspend command. If the hub is not suspended, any resume will be confined to that individual port and reflected to the host through a port change indication in the Hub Status Change Endpoint. If the hub is suspended, a resume on this port will be forwarded to the host, but other resume events will not be seen on that port. The host may resume the port by sending a ClearPortSuspend command. Upstream Port The upstream port includes the transmitter and the receiver state machine. The transmitter and receiver operate in high speed and full speed depending on the current hub configuration. The transmitter state machine monitors the upstream facing port while the hub repeater has connectivity in the upstream direction. This monitoring activity prevents propagation of erroneous indications in the upstream direction. In particular, this machine prevents babble and disconnect events on the downstream facing ports of this hub from propagating and causing the hub to be disabled or disconnected by the hub to which it is attached. This enables the hub to only disconnect the offensive port on detecting a babble from it. Power Switching TetraHub includes interface signals for external port power switches. Both ganged and individual (for each port) configurations are supported, with individual switching being the default. Initially all ports are unpowered. After enumerating, the host may power each port by sending a SetPortPower command for that port. The power switching and overcurrent detection of downstream ports is managed by control pins connected to an external power switch device. PWR [n]# output pins of the CY7C65640A series are connected to the respective external power switch's port power enable signals. (Note that each port power output pin of the external power switch must be bypassed with an electrolytic or tantalum capacitor as required by the USB specification. These capacitors supply the inrush currents, which occur during downstream device hot-attach events.) [+] Feedback |
Similar Part No. - CY7C65640A_11 |
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Similar Description - CY7C65640A_11 |
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