NCR RealPOS 70, User Manual

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Chapter 12: Cash Drawer Interface 12-7
Within the ICH4, the General Purpose I/O ports are addressed using an
offset read from the GPIO Base Address Register, [GPIOBASE] (offset
0x58). The base address included in Bits [15:6] is assigned by the BIOS.
The GPIO Control Register [GPIO_CNTL] (offset 0x5C) has a R/W bit
[4] that enables(1)/disables(0) the decode of the I/O range pointed to by
the GPIO Base register and enables/disables the GPIO function. The
GPIO Control Register is set by the BIOS to enable GPIO.
Intel
®
82801DB ICH4 Datasheet
GPIO_USE_SEL2—GPIO Use Select 2 Register
Offset Address: GP30h Attribute: R/W
Default Value: 00000FFFh Size: 32-bit
Lockable: No Power Well: Core
Bit Description
31:0
GPIO_USE_SEL2[43:32] — R/W. Each bit in this register enables the
corresponding GPIO (if it exists) to be used as a GPIO, rather than for
the native function.
0 = Signal used as native function.
1 = Signal used as a GPIO.
For 7402, cash drawer bits GPIO_USE_SEL2 [35:32] will be set =1 for
use as a GPIO, write value = read value ANDed with 0xF.
After a full reset (RSMRST#) all multiplexed signals in the resume and
core wells are configured as their native function rather than as a
GPIO. After just a PCIRST#, the GPIO in the core well are configured as
their native function.
LPC Interface Bridge Registers (D31:F0)
GP_IO_SEL2—GPIO Input/Output Select 2 Register
Offset Address: GP34h Attribute: R/W
Default Value: 00000000h Size: 32-bit
Lockable: No Power Well: Core