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CY7C65621 Datasheet(PDF) 5 Page - Cypress Semiconductor |
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CY7C65621 Datasheet(HTML) 5 Page - Cypress Semiconductor |
5 / 27 page CY7C65621/31 Document #: 001-52934 Rev. *C Page 5 of 27 Downstream Ports The CY7C65621/31 supports a maximum of four downstream ports, each of which may be marked as usable or removable in the extended configuration (0xD2 EEPROM load or 0xD4 EEPROM load, see Configuration Options on page 13. Downstream D+ and D– pull down resistors are incorporated in CY7C65621/31 for each port. Before the hubs are configured, the ports are driven SE0 (Single Ended Zero, where both D+ and D– are driven low) and are set to the unpowered state. When the hub is configured, the ports are not driven, and the host may power the ports by sending a SetPortPower command for 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 hubs back to the host through the Status Change Endpoint (endpoint 1). Upon receipt of SetPortReset request for a port with a device connected, the hub does as follows: ■ Performs a USB reset on the corresponding port ■ Puts the port in an enabled state ■ Enables the green port indicator for that port (if not previously overridden by the host) ■ Enables babble detection when the port is enabled. Babble consists of a non idle condition on the port after EOF2. If babble is detected on an enabled port, that port is disabled. A ClearPortEnable request from the host also disables the specified port. Downstream ports can be individually suspended by the host with the SetPortSuspend request. If the hub is not suspended, a remote wakeup event on that port is reflected to the host through a port change indication in the Hub Status Change Endpoint. If the hub is suspended, a remote wakeup event on this port is forwarded to the host. 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 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. Power Switching The CY7C65621/31 includes interface signals for external port power switches. Both ganged and individual (per-port) configu- rations 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 request for that port. The power switching and over-current detection of downstream ports is managed by control pins connected to an external power switch device. PWR [n]# output pins of the CY7C65621/31 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. The polarity of this pin can be configured through the EEPROM; see 0xD4 Load on page 14. Overcurrent Detection Overcurrent detection includes 8 ms of timed filtering by default. This parameter is configured from the external EEPROM in a range of 0 ms to 15 ms for both enabled ports and disabled ports individually. Detection of overcurrent on downstream ports is managed by control pins connected to an external power switch device. The OVR[n]# pins of the CY7C65621/31 series are connected to the respective external power switch's port overcurrent indication (output) signals. After detecting an overcurrent condition, hub reports overcurrent condition to the host and disables the PWR# output to the external power device. The polarity of the OVR pins can be configured through the EEPROM; see 0xD4 Load on page 14. Port Indicators The USB 2.0 port indicators are also supported directly by CY7C65621/31. According to the specification, each downstream port of the hub optionally supports a status indicator. The presence of indicators for downstream facing ports is specified by bit 7 of the wHubCharacteristics field of the hub class descriptor. The default CY7C65621/31 descriptor specifies that port indicators are supported (wHubCharacteristics, bit 7 is set). If port indicators are not included in the hub, disable this bit through EEPROM settings. Each port indicator pin is strategically located directly on the opposite edge of the port with which it is associated. A port indicator provides two colors: green and amber. This is usually implemented as two separate LEDs, one amber and the other green. A combination of hardware and software control is used to inform the user of the current status of the port or the device attached to the port and to guide the user through problem resolution. Colors and blinking provide information to the user. The significance of the color of the LED depends on the opera- tional mode of CY7C65621/31. The CY7C65621/31 port indicators has two modes of operation: automatic and manual. On power up the CY7C65621/31 defaults to automatic mode, where the color of the Port Indicator (green, amber, off) indicates the functional status of the CY7C65621/31 port. In automatic mode, the CY7C65621/31 turns on the green LED whenever the port is enabled and the amber LED when an overcurrent condition is detected. The color of the port indicator is set by the port state machine. Blinking of the LEDs is not supported in automatic mode. Table 1 identifies the mapping of color to port state in automatic mode. [+] Feedback |
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Similar Description - CY7C65621_11 |
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