P R E L I M I N A R Y

AMD

 

 

 

 

 

4

PDC

0

Power Down Command. When PDC is set to 1, the power down cy-

 

 

 

cle of the BIU power down state machine will begin. PDC will auto-

 

 

 

matically clear itself after completion of the power down operation.

3

SYSINT

0

System Interrupt. SYSINT Indicates a 1 after the system issues an

 

 

 

interrupt command to the 80188 core by writing to the INT2EC bit of

 

 

 

the GCR register (SIR0). SYSINT will become cleared to a 0 when

 

 

 

the 80188 core writes a 1 to SYSINT.

 

 

2

INT2SYS

0

Interrupt To System. When INT2SYS is set to a 1, an interrupt is

 

 

 

generated to the system, provided that the ECWAIT bit (SIR0[4]0 is

 

 

 

set to 0. INT2SYS will stay set at 1 until the system clears it by

 

 

 

writing a 1 to ECINT (bit 3 of SIR0). Writing a 0 to INT2SYS will have

 

 

 

no effect.

 

 

1

SYSINTM

0

System Interrupt Mask. When SYSINTM is set to a 1, system-gen-

 

 

 

erated interrupts (through the SYSINT bit of MIR0) are allowed to

 

 

 

be passed to the 80188. When SYSINTM is reset to 0, no

 

 

 

system-generated interrupts will be passed to the 80188.

0

PWDNDN

0

Power Down Done. When Power Down mode is completed, then

 

 

 

PWDNDN will automatically become set to 1 and an interrupt to the

 

 

 

80188 core will be generated. The 80188 core may clear the

 

 

 

PWDNDN bit by first writing a 1 to PWDNDN and then writing a 0 to

 

 

 

PWDNDN. Note that PWDNDN will read as a 0, after writing a 1 to

 

 

 

PWDNDN, but a 0 must still be written to PWDNDN in order to com-

 

 

 

plete the reset operation. If a 0 is not written to PWDNDN, then the

 

 

 

PWDNDN will be permanently held in reset.

 

 

MIR1: Power Up Clock Time [3:0] (PUCT)

This register is used to determine the length of time that will be used to allow the CLKIN buffer circuit to power up and stabilize before the end of the power down cycle.

The length of the power up phase will be the value of the PUCT times 0.5 msec.

Bit

Name

Reset Value

Description

 

 

 

 

 

7:4

PUCT[3:0]

0000b

Length of the power up stabilization time for the CLKIN buffer cir-

 

 

 

cuitry. The resolution of the power up clock timer is in increments of

 

 

 

16x (Period of PMX). The nominal PMX1/2 crystal value is

 

 

 

32.768 kHz, resulting in a resolution of 16 x 31.25 μs = 500 μs.

3:0

Reserved

Reserved. Must be written as a 0. Reads of this bit produce

 

 

 

undefined data.

MIR2: Power Down Length Count [7:0] (PDLC)

This register is used to determine the length of power down cycles. Before execution of the power down se- quence, the 80188 core must load the PDLC counter.

Upon execution of the power down sequence, the PDLC value will be counted down to zero and the power down cycle will end.

Bit

Name

Reset Value

Description

 

 

 

 

 

0

PDLC[7:0]

00h

Lower 8 bits of the length of the power down cycle counter. The

 

 

 

resolution of the power down length counter is in increments of

 

 

 

PMX1/2 periods. The nominal PMX1/2 crystal Value is 32.768 kHz,

 

 

 

resulting in a resolution of 31.25 μs.

Am79C930

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AMD Am79C930 manual MIR1 Power Up Clock Time 30 Puct, MIR2 Power Down Length Count 70 Pdlc