Configuration Register Description
accessed and is used to select which of the Configuration
Registers are to be accessed at port 3F1H (371H).
The configuration registers consist of the Configuration
Select Register (CSR) and Configuration Registers CR-
00 -CR-29. The configuration select register is written to
by writing to port 3F0H (or 370H). The Configuration
Registers CR-00; CR-29 are accessed by reading or
writing to port 3F1H (or 371H).
Configuration Registers CR00 -CR29
These registers are set to their default values at power up
and are not affected by RESET (except where explicitly
defined that a hardware reset causes that bit to be reset
to default). They are accessed at port 3F1H (or 371H).
Refer to the following descriptions for the function of each
configuration register.
Configuration Select Register (CSR)
This register can only be accessed when the chip is in the
Configuration Mode. This register, located at port 3F0H
(370H), must be initialized upon entering the
Configuration Mode before the configuration registers can
be
CR00
This register can only be accessed when the chip is in the
Configuration Mode and after the CSR has been
initialized to 00H. The default value of this register after
power up is 28H.
Table 47 - CR00
BIT NO.
BIT NAME
DESCRIPTION
0, 1
IDE ENABLE/
Bits (Note 1)
10
Alternate
Function
00 - IDE, IRRX2, IRTX2, IRQ_H disabled (Default)
01 - Reserved (IDE, IRRX2, IRTX2, IRQ_H disabled)
10 - IDE Enabled
11 - IRRX2, IRTX2, IRQ_H Enabled
Read only. Read as 0
2
3
Reserved
FDC Power (see A high level on this bit, supplies power to the FDC (default). A low
note _PWRDN)
Reserved
Valid
level on this bit puts the FDC in low power mode.
4,5,6
7
Read only. A read returns bit 5 as a 1 and bits 4 and 6 as a 0.
A high level on this software controlled bit can be used to indicate
that a valid configuration cycle has occurred. The control software
must take care to set this bit at the appropriate times. Set to zero
after power up. This bit has no effect on any other hardware in the
chip.
Note 1: When "0x" is selected, 30ua pull-ups are active on the "nIDEEN, nHDCS0 and nHDCS1 pins", at all other
times, the pull-ups are disabled.
When "11" is selected, IRQ_H is available as an IRQ output, and IRRX2 and IRTX2 are available as alternate
IR pins (pull-ups disabled). When "10" is selected, nIDEEN, nHDCS0 and nHDCS1 are used to control the IDE
interface (pull-ups disabled).
120
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