AMD Am79C930 - Manual (Page 25)

P R E L I M I N A R Y AMD
25 Am79C930
PIN DESCRIPTIONS
Pins with Internal Pull Up or Pull
Down Devices
Several pins of the Am79C930 device include internal
pull up or pull down devices. With the exception of the
RESET pin, these pins are fully programmable as inputs
or outputs when the PCMCIA mode has been selected.
A subset of these pins is programmable when the ISA
Plug and Play mode has been selected. These pins will
come up after RESET in the high impedance state with
the pull up or pull down device actively determining the
value of the pin, unless an external driving source
overdrives the pull up or pull down device. VINITDN
bit (MIR9[2]) is used to turn off all pull up and pull
down devices.
The following list indicates those pins that contain pull
up and pull down devices:
PCMCIA Mode Internal Device Size of Internal
Pin Name Type Device
USER[6]/IRQ5 pull up > 100K
Ω
USER[5]/IRQ4 pull up > 100K
Ω
USER[4]/LA17 pull up > 100K Ω
USER[3]/SA16 pull up > 100K
Ω
USER[2]/LA19 pull up > 100K
Ω
USER[1]/IRQ12 pull down > 100K
Ω
USER[0]/RFRSH pull down > 100K
Ω
LLOCKE/SA15 pull down > 100K Ω
ANTSLT /LA23 pull up > 100K Ω
TXDATA /LA20 pull up > 100K
Ω
TXCMD/LA21 pull down > 100K
Ω
RXC/IRQ10 pull up > 100K
Ω
USER7/IRQ11 pull up > 100K Ω
LFPE pull up > 100K Ω
HFPE pull up > 100K
Ω
RXPE pull up > 100K
Ω
ANTSLT pull down > 100K
Ω
TXCMD pull up > 100K
Ω
TXPE pull up > 100K Ω
SDCLK pull up > 100K Ω
SDDATA pull up > 100K
Ω
SDSEL [3] pull up > 100K
Ω
SDSEL [2] pull up > 100K
Ω
SDSEL [1] pull up > 100K Ω
ACT pull up > 100K Ω
LNK pull up > 100K
Ω
TXMOD pull up > 100K
Ω
STSCHG /BALE pull up > 100K
Ω
TXC pull up > 100K
Ω
Following the RESET operation, the Am79C930 firm-
ware or driver software should appropriately program
the D bits of TIR and TCR registers, and then set the FN
and EN bits of TIR and TCR registers to set the values
and directions of each of these programmable pins.
Once these operations have been performed, the soft-
ware should then program the INITDN bit of MIR9 in or-
der to disable all of the pull up and pull down devices.
Unused programmable pins should be programmed for
output mode, or may be left in the default high imped-
ance state if an external pull down or pull up device is left
connected to the pin. Unused programmable pins must
not be programmed for input mode with no external
source (pull-device or driver) connected and the INITDN
bit of MIR9 set to a 1, since this could lead to unaccept-
able levels of power consumption by the Am79C930 de-
vice. For more information on programmable pins, see
the Multi-Function Pins section.
Configuration Pins
PCMCIA
PCMCIA/ISA Bus Interface Select Input
The value of this pin will asynchronously determine the
operating mode of the Am79C930 device, regardless of
the state of the RESET pin and regardless of the state of
the CLKIN pin. If the PCMCIA pin is tied to VCC, then the
Am79C930 controller will be programmed for PCMCIA
Bus Mode. If the PCMCIA pin is tied to VSS, then the
Am79C930 controller will be programmed for ISA Plug
and Play Bus Interface Mode.