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Interrupt Level Setting
Most peripheral devices in an AT compatible computer coordinate I/O (input/output) operations with the
microprocessor by means of hardware interrupts. An interrupt is a request by a device that the computer
suspend the program it's currently running, and perform an I/O operation. The PCI4 Potentiostat generates an
interrupt at the end of each data point.
All PCI devices in a computer generally share one interrupt level.
Register Address
The PCI4 Potentiostat card set, like virtually all IBM compatible expansion cards, has hardware registers that the
computer must be able to access. These registers are located at a specific address in the memory address space
of the computer's microprocessor. Addresses are expressed in the hexadecimal numbering system where the
digits are 1,2,3,4...8,9,A,B,C,D,E,F. We will always precede a hexadecimal number with the prefix 0x, e.g.
0x22F.
The PCI4 requires a 64 byte memory space for it's hardware control registers. The Windows Device Manager
will show several address spaces for a PCI4 device. The third space is the I/O registers for the PCI4. The other
memory spaces are used in PCI configuration.
Changing the Auxiliary Analog Output Scaling
A setting in the "GAMRY5.INI" file allows you to change the scaling of the D/A converter used to generate the
auxiliary analog output.
The default setting configures this D/A converter for a bipolar output of ± 5 volts with a bit resolution of 2.5
mV/bit. You can switch to a unipolar output of 0 to 10 volts, still with a bit resolution of 2.5 mV/bit.
The D/A scaling is controlled by a field in the [PCI4yyy-xxxxx] section of the "GAMRY5.INI" file. This field has
the form:
AUXDACRES=2.5E-3,0
The final 0 indicates that the scaling is bipolar. If this digit was a 1, the scaling would be unipolar.
Appendix C -- Changing PCI4 Settings --
6-8
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