PC87393 datasheet(32/148 Pages) NSC

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2.0 Device Architecture and Configuration (Continued)

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continuous register set. Interrupt Number and Wake-Up on IRQ Enable (index 70h) and IRQ Type Select (index 71h) allocate

an IRQ line to the block and control its type. DMA Channel Select 0 (index 74h) allocates a DMA channel to the block, where

applicable. DMA Channel Select 1 (index 75h) allocates a second DMA channel, where applicable.

Special Conﬁguration

The vendor-defined registers, starting at index F0h, control function-specific parameters such as operation modes, power

saving modes, pin TRI-STATE, clock rate selection, and non-standard extensions to generic functions.

2.2.5

Default Configuration Setup

The default configuration setup of the PC8739x can include two reset types, described below. See specific register descrip-

tions for the bits affected by each reset type.

• Software Reset

This reset is enabled by bit 1 of the SIOCF1 register, which resets all logical devices. A software reset also resets most

bits in the SuperI/O control and configuration registers (see Section 2.10 for the bits not affected). This reset does not

affect register bits that are locked for write access.

• Hardware Reset

This reset is activated by the assertion of the LRESET input. It resets all logical devices. It also resets all SuperI/O control

and configuration registers.

In event of a hardware reset, the PC8739x wakes up with the following default configuration setup:

— The conﬁguration base address is 2Eh or 4Eh, according to the BADDR strap pin value, as shown in Table 5.

— All logical devices are disabled, with the exception of the X-Bus which remains functional but whose registers cannot

be accessed.

— All multiplexed GPIO pins are conﬁgured according to the strap pins. When conﬁgured as GPIO, they have an internal

static pull-up (default direction is input) except GPIO36.

In event of either a hardware or a software reset, the PC8739x wakes up with the following default configuration setup:

— The legacy devices are assigned with their legacy system resource allocation.

— The National proprietary functions are not assigned with any default resources and the default values of their base

addresses are all 00h.

2.2.6

Power States

The following terminology is used in this document to describe the various possible power states:

• Power On

VDD is active.

• Power Off

VDD is inactive.

2.2.7

Address Decoding

A full 16-bit address decoding is applied when accessing the configuration I/O space as well as the registers of the functional

blocks. However, the number of configurable bits in the base address registers varies for each logical device.

The lower 1, 2, 3, 4 or 5 address bits are decoded within the functional block to determine the offset of the accessed register,

within the logical device’s I/O range of 2, 4, 8, 16 or 32 bytes, respectively. The rest of the bits are matched with the base

address register to decode the entire I/O range allocated to the logical device. Therefore the lower bits of the base address

register are forced to 0 (read only), and the base address is forced to be 2, 4, 8, 16 or 32 byte-aligned, according to the size

of the I/O range.

The base address of the FDC, Serial Port 1, Serial Port 2 with FIR are limited to the I/O address range of 00h to 7FXh only

(bits 11-15 are forced to 0). The Parallel Port base address is limited to the I/O address range of 00h to 3F8h. The addresses

of the non-legacy logical devices, including the GMP, MIDI and X-Bus, are configurable within the full 16-bit address range

(up to FFFXh).

In some special cases, other address bits are used for internal decoding (such as bit 10 in the Parallel Port). For more details,

see the description of the base address register for each logical device.

The X-Bus extension serves as a bridge from the LPC to the X-Bus. For module control and security function registers, the

16-bit base address is applied through the configuration address space. The lower 4 address bits are decoded within the X-

Bus for accessing each register. The address ranges in the LPC I/O space, LPC memory space and FWH memory space

that are bridged to the X-Bus are defined in the SuperI/O configuration section for the X-Bus bridge. The number of address

bits used for this decoding varies according to the specified zones and their sizes. See Section 2.19.2 and Section 2.19.3

for details of the address range specifications.

PC87393 Datasheet(PDF) 32 Page - National Semiconductor (TI)

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