Cypress Semiconductor CY7C68301C Manual de usuario descargar pdf (Pagina 14)

CY7C68300C, CY7C68301C

CY7C68320C, CY7C68321C

Document Number: 001-05809 Rev. *K Page 14 of 44

Figure 7. SYSIRQ Latching Algorithm

DRVPWRVLD

When this pin is enabled with bit 0 of configuration address 0x08

(DRVPWRVLD Enable), the AT2LP informs the host that a

removable device, such as a CF card, is present. The AT2LP

uses DRVPWRVLD to detect that the removable device is

present. Pin polarity is controlled by bit 1 of configuration

address 0x08. When DRVPWRVLD is deasserted, the AT2LP

reports a “no media present” status (ASC = 0x3A, ASQ = 0x00)

when queried by the host. When the media is detected again, the

AT2LP reports a “media changed” status to the host

(ASC = 0x28, ASQ = 0x00) when queried.

When a removable device is used, it is always considered by the

AT2LP to be the IDE master device. Only one removable device

may be attached to the AT2LP. If the system only contains a

removable device, bit 6 of configuration address 0x08 (Search

ATA Bus) must be set to ‘0’ to disable ATA device detection at

startup. If a non-removable device is connected in addition to a

removable media device, the non removable device must be

configured as IDE slave (device address 1).

GPIO Pins

The GPIO pins enable a general purpose input and output

interface. There are several different interfaces to the GPIO pins:

■ Configuration bytes 0x09 and 0x0A contain the default settings

for the GPIO pins upon initial AT2LP configuration.

■ The host can modify the settings of the GPIO pins during

operation. This is done with vendor-specific commands

described in Programming the EEPROM on page 35.

■ The status of the GPIO pins is returned on the interrupt endpoint

(EP1) in response to a SYSIRQ. See SYSIRQ on page 13 for

SYSIRQ details.

LOWPWR#

LOWPWR# is an output pin that is driven to ‘0’ when the AT2LP

is not in suspend. LOWPWR# is placed in High Z when the

AT2LP is in a suspend state. This pin only indicates the state of

the AT2LP and must not be used to determine the status of the

USB host because of variations in the behavior of different hosts.

USB Interrupt

Pipe Polled?

Yes

NAK Request

SYSIRQ=1?

Latch State of IO Pins

Set Int_Data = 1

Int_Data = 1?

Return Interrupt Data

Set Int_Data = 0

Yes

Int_Data = 0

and

SYSIRQ=0?

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