PCI7421 datasheet(65/298 Pages) TI

65 / 298 page

3−9

3.5.7

Integrated Pullup Resistors for PC Card Interface

The PC Card Standard requires pullup resistors on various terminals to support both CardBus and 16-bit PC Card

configurations. The PCI7x21/PCI7x11 controller has integrated all of these pullup resistors and requires no additional

external components. The I/O buffer on the BVD1(STSCHG)/CSTSCHG terminal has the capability to switch to an

internal pullup resistor when a 16-bit PC Card is inserted, or switch to an internal pulldown resistor when a CardBus

card is inserted. This prevents inadvertent CSTSCHG events. The pullup resistor requirements for the various

UltraMedia interfaces are either included in the UltraMedia cards (or the UltraMedia adapter) or are part of the existing

PCMCIA architecture. The PCI7x21/PCI7x11 controller does not require any additional components for UltraMedia

support.

3.5.8

SPKROUT and CAUDPWM Usage

The SPKROUT terminal carries the digital audio signal from the PC Card to the system. When a 16-bit PC Card is

configured for I/O mode, the BVD2 terminal becomes the SPKR input terminal from the card. This terminal, in

CardBus applications, is referred to as CAUDIO. SPKR passes a TTL-level binary audio signal to the

PCI7x21/PCI7x11 controller. The CardBus CAUDIO signal also can pass a single-amplitude binary waveform as well

as a PWM signal. The binary audio signal from each PC Card sockets is enabled by bit 1 (SPKROUTEN) of the card

control register (PCI offset 91h, see Section 4.38).

Older controllers support CAUDIO in binary or PWM mode, but use the same output terminal (SPKROUT). Some

audio chips may not support both modes on one terminal and may have a separate terminal for binary and PWM.

The PCI7x21/PCI7x11 implementation includes a signal for PWM, CAUDPWM, which can be routed to an MFUNC

terminal. Bit 2 (AUD2MUX), located in the card control register, is programmed to route a CardBus CAUDIO PWM

terminal to CAUDPWM. See Section 4.36, Multifunction Routing Register, for details on configuring the MFUNC

terminals.

Figure 3−5 illustrates the SPKROUT connection.

Speaker

Subsystem

BINARY_SPKR

System

Core Logic

PCI7x21/

PCI7x11

CAUDPWM

SPKROUT

PWM_SPKR

Figure 3−5. SPKROUT Connection to Speaker Driver

3.5.9

LED Socket Activity Indicators

The socket activity LEDs are provided to indicate when a PC Card is being accessed. The LEDA1 and LEDA2 signals

can be routed to the multifunction terminals. When configured for LED outputs, these terminals output an active high

signal to indicate socket activity. LEDA1 indicates socket A (card A) activity, and LEDA2 indicates socket B (card B)

activity. The LED_SKT output indicates socket activity to either socket A or socket B. See Section 4.36, Multifunction

Routing Status Register, for details on configuring the multifunction terminals.

The active-high LED signal is driven for 64 ms. When the LED is not being driven high, it is driven to a low state. Either

of the two circuits shown in Figure 3−6 can be implemented to provide LED signaling, and the board designer must

implement the circuit that best fits the application.

The LED activity signals are valid when a card is inserted, powered, and not in reset. For PC Card-16, the LED activity

signals are pulsed when READY(IREQ) is low. For CardBus cards, the LED activity signals are pulsed if CFRAME,

IRDY, or CREQ are active.

PCI7421 数据表(PDF) 65 Page - Texas Instruments

PCI7421 数据表(HTML) 65 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载