Measurement Computing STLITE-PCI-8x User Manual

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previously programmed as input-only are not driven.

Bits 4-7 of this register operate as “Write-1-To-Set.” Writing a “1” to any bit in the upper nibble will drive the
corresponding GPIO bit high even if it has been previously programmed as bi-directional. Bits previously
programmed as input only are not driven.

Writing a “0” to this register has no effect, while reading from this register returns the last value poked in.

GPIO IN Register (0x67 offset of PCI Header)

Read Only

SDO

RESERVED

GPIO3

GPIO2

GPIO1

GPIO0

This register allows read-back of the serial data (SDO) from either of the two A/D converters used to measure
slot temperature, power supply voltages or fan current.

The lower nibble (bits 0-3) is reserved by the 21150 bridge chip. Reading from this portion of the register will
return all zeros.

NOTE: When reading the upper nibble (bits 4-7), be sure to mask of unwanted bits to avoid

return of incorrect data.

GPIO CNTRL Register (0x66 offset of PCI Header)

Read/Write

GPIO3_BI

GPIO2_BI

GPIO1_BI

GPIO0_BI

GPIO3_IN

GPIO2_IN

GPIO1_IN

GPIO0_IN

This register configures each of the STLITE-PCI-8T motherboard’s GPIO bits as either bi-directional or input
type.

Bits 0-3 of this register operate in a “Write-1-To-Clear” manner. Writing a “1” to any bit in the lower nibble
will configure the corresponding GPIO bit as input type.

Bits 4-7 of this register operate as “Write-1-To-Set.” Writing a “1” to any bit in the upper nibble will configure
the corresponding GPIO bit as bi-directional.

Writing the value “0” to this register has no effect. Reading from this register returns the last value poked in.