UPD72871F1 datasheet(28/48 Pages) NEC

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Preliminary Data Sheet S13925EJ2V0DS00

µµµµPD72870,72871

3.1.16 Offset_3C

Interrupt Line Register

This register provides the interrupt line routing information specific to the

µPD72870, 72871, the NEC’s

implementation of the 1394 OpenHCI specification.

Bits

R/W

Description

7-0

R/W

Default value of 00H. It specifies which input of the host system interrupt controller the

interrupt pin of the

µPD72870, 72871 is connected to.

3.1.17 Offset_3D

Interrupt Pin Register

This register provides the interrupt line routing information specific to the

µPD72870, 72871, the NEC’s

implementation of the 1394 OpenHCI specification.

Bits

R/W

Description

7-0

Constant value of 01H. It specifies PCI INTA is used for interrupting the host system.

3.1.18 Offset_3E

Min_Grant Register

This register specifies how long of a burst period the

µPD72870, 72871 needs, assuming a clock rate of 33MHz.

Resolution is in units of ¼

µs. The value should be loaded into the register from the external serial EEPROM upon

power-up reset, and access to this register through PCI-bus is prohibited.

Bits

R/W

Description

7-0

Default value of 00H. Its value contributes to the desired setting for Latency Timer value.

3.1.19 Offset_3F

Max Lat Register

This register specifies how often the

µPD72870, 72871 needs to gain access to the PCI-bus, assuming a clock

rate of 33MHz. Resolution is in units of ¼

µs. The value should be loaded into the register from the external serial

EEPROM after hardware reset, and access to this register through PCI-bus is prohibited.

Bits

R/W

Description

7-0

Default value of 00H. Its value contributes to the desired setting for Latency Timer value.

3.1.20 Offset_40

PCI_OHCI_Control Register

This register specifies the control bits that are IEEE1394 OpenHCI specific. Vendor options are not allowed in this

Bits

R/W

Description

0R/W

PCI global SWAP Default value of 0. When this bit is 1, all quadrates read from and written to

the PCI Interface are byte swapped, thus a “PCI Global Swap”. PCI addresses for expansion

ROM and PCI Configuration registers, are, however, unaffected by this bit. This bit is not

required for motherboard implementations.

31-1

Reserved Constant value of all 0.

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