CDP1020 Просмотр технического описания (PDF) - Intersil

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CDP1020

SMBus/I2C ACPI Dual Device Bay Controller

Intersil 

CDP1020

delay time is set at system power on whenever the CDP1020 is

initialized by writing the appropriate value into the ITO[2:0] bit

field of the SFR. As shown in the SFR text, the insertion time-

out delay can range from 0s to 5.6s in increments of 800ms.

The feature that makes the CDP1020 insertion time out

function different from a simple insertion delay is that the

CDP1020 will begin to flash the bay status LED green

immediately after the device has been detected (if the

DEVSTSCHG_EN flag for the bay is set). This is important

because it gives the user instant feedback that the device

has been recognized.

It is important to note that even though the bay status LED is

flashing, the CDP1020 has not responded to the device

insertion. During the insertion time out period, the status bits

(1394PRSN_STS and USBPRSN_STS) remain clear and the

bay state is NOT transitioned in the Device Inserted state.

Thus, if the OS were to read the CDP1020 during the insertion

time out period, it would not know that a device was in the bay.

Once the insertion time out period is over, the CDP1020 will

generate an insertion event (assuming the

DEVSTSCHG_EN flag is set) and the state controller will

enter the Device Inserted state.

It is important to note that while waiting for the insertion time

out, the CDP1020 has not fully registered the device in the

bay. Thus, if the device were forcibly removed during this

time, a removal event would not be generated. The

CDP1020 would simply reset the insertion time out counter

and stop flashing the bay status LED.

Bay Empty

A bay empty state is defined exclusively as both the presence

inputs for the bay (1394PRx and USBPRx) de-asserted. The

state of these pins is controlled by the insertion and removal

of devices in the bay. As shown in Figure 9, the insertion of a

device (and the assertion of one or both of the presence pins)

causes the CDP1020 to recognize that a device is in the bay.

If the DEVSTSCHG_EN flag for the bay is set, an insertion

interrupt event will be generated and the state machine to

transition bay state from Bay Empty (%000) to Device

Inserted (%001).

Typically the Bay Empty state will be returned to from either the

Device Inserted state (before the device has been enabled) or

the Device Removal Allowed state (after the OS has powered

down the device). However, the Bay Empty state can also be

entered from Removal Requested and Device Enabled states if

the device was forcibly removed from the system. In all cases, if

the CDP1020 detects that both presence pins have been

deasserted, the Bay Empty state will be entered and the

PWREN output for the VID MOSFET gate driver will be

disabled.

The bay empty state is reflected by the bay state machine by

setting BAY_ST[2:0] field (bits 6:4 of the bay status register)

to %000. The bay empty state can be entered from any of

the other four bay states and is entered exclusively through

hardware transitions controlled by the CDP1020; OS writing

into the BCER cannot change the bay state to Bay Empty.

Entering the Bay Empty state from any state other than

Removal Allowed will cause the CDP1020 to generate a

removal interrupt event if the DEVSTSCHG_EN bit in the

BCER is set. A removal event will be generated if the bay was

in the Removal Allowed state and both the REMEVTWAK the

DEVSTSCHG_EN bits in the BCER are set. In both cases, the

CDP1020 will notify the host system via the ALRT pin.

In the Bay Empty state the bay status LED (LEDGx and

LEDAx) outputs will be off.

Device Inserted State

The Device Inserted state, %001, is entered in one of two

manners. When a device is inserted, the CDP1020 will

transition to the Device Inserted state (after the insertion time

out period) if the DEVSTSCHG_EN bit for the bay in question

is set. In such a case, the CDP1020 will generate an insertion

event, set the DEVSTSCHG bit in the BSTR, flash the bay

status LED green and notify the OS through the ALRT pin.

Alternately, the OS can transition the CDP1020 to the Device

Inserted state by writing a %001 to the BAY_STREQ bit field

in the BCER. This can only be done from any other bay state

as long as a device is inserted in the bay.

While in the CDP1020 is in the Device Inserted state the OS

will typically engage the software controlled lock for the bay,

enable VID to the bay and enumerate the device on its native

communication bus. While in this state, the bay status LED

will flash green at 1Hz.

Device Enabled

In the Device Enabled state, the device inserted into the bay

has VID enabled and is fully functional. This state cannot be

entered through hardware action; only the OS writing %010

to the BAY_STREQ bits in the BCER can transition the bay

state to Device Enabled.

In the Device Enabled state, if the presence pins are de-

asserted at any time, the CDP1020 hardware will

automatically transition the bay state to Bay Empty, clear the

PWR_CTL bit and disable the PWRENx outputs. The

PWRENx and PWR_CTL states are not affected by the state

transitions to the Device Enabled state.

While in this state the bay status LED will be solid green.

Device Removal Requested

The Device Removal Requested state, like the Device

Inserted state, can be entered either through an OS write to

the BCERx or through hardware actions.

Upon the assertion of the bay REMREQ input, the CDP1020

will set the REMREQ_STS bit in the BSTR if there is a device

in the bay (i.e., 1394PRSN_STS or USBPRPRSN_STS = 1).

A removal request interrupt event will be generated if the

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