Measurement Computing STLITE-CPCI-xxx - Manual (Page 17)

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7. REGISTER MAP
7.1 REGISTER MAP
The STLITE -CPCI-8R/16R provides two sets of general-purpose I/O bits (GPIO0-GPIO3). The first set of
GPIO control bits is provided by the PCI Host card’s 21150 PCI-PCI bridge chip. The second set is provided by
the Expansion board’s 21150 PCI-PCI bridge chip.
The PCI Host card GPIO control bits provide direct control over the user-configurable watchdog timer circuit.
The Expansion card GPIO bits interface bits interface directly to the serial control bits used to configure and
control the voltage, temperature and current measuring A/D converters.
7.2 EXPANSION BOARD 21150 BRIDGE REGISTERS
GPIO OUT Register ( 0x65 offset of PCI Header ) Read/Write
D7 D6 D5 D4 D3 D2 D1 D0
OE/ALARM_OFF X S_CLK SDI OE/ALARM_ON X S_CLK SDI
GPIO3 GPIO2 GPIO1 GPIO0 GPIO3 GPIO2 GPIO1 GPIO0
This register provides access to the serial data I/O control bits. The Expansion board provides these bits for the
user to control the precision A/D converters, which measure the various chassis temperatures, voltages and fan
currents.
This register also provides direct control over the ALARM output bit and the ALARM relay output bits
described in Section 6.2. Configuring the ALARM function requires that the WD configuration bit (bits 1 or 5)
in the HOST 21150 GPIO OUT register (0x65) be configured in conjunction with bits 3 or 7 of this register.
To address specific A/D converters, use the GPIO control bits and the following chip select lookup table. See
the TI TLV2548 datasheet for more specific information concerning the configuration of the A/D converters.
SDI S_CLK A/D Function
L L A/D_0 Measures voltages, cavity temperature and fan current
H L A/D_1 Measures temperature of CPCI slots 0-7 ( –16R+ Only)
L H A/D_2 Measures temperature of CPCI slots 8-15 (-8R+ and –16R+)
The order of operations for programming the A/D converters should include:
1. Selecting the specific A/D converter chip (see chip select table above).
2. Configuring the A/D converter (see TI TLV2548 datasheet for specifics).
Note: The Expansion board hardware provides each of the A/D converters with an external, precision
reference. Attempting to re-configure the A/D converters to use an internal reference will produce
inaccurate results.
3. Read/Write data to and or from the A/D converter.
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 drive the corresponding GPIO bit low even if it has been previously programmed as bi-directional. Bits
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.