spec - Local Sector 7 web page

Oxford/Tennelec/Nucleus PCA Mutlipor t, PCA II, PCA-3config file:GP_PCA_M = gpib_addressPC_PCA3 = base_addressPC_PCAII = device_name base_address INTR|POLLedconf devices screen:MCAs DEVICE ADDR MODE TYPEYES 7 The Nucleus PCA Multport (GPIB)YES 0x210 The Nucleus PCA-3 MCA BoardYES 0x1e0 POLL The Nucleus PCA II MCA BoardYES /dev/pca 0x1e0 INTR The Nucleus PCA II MCA BoardThe PCA II MCA can be used in either a user-level I/O mode or in an interruptdrivenmode with the CSS provided driver. The interrupt-driven mode allows deadtimecorrections and more accurate counting times. See the drivers/README file inthe spec distribution for information on installing the driver.If using the interrupt-driven mode, note the following: Apparently, the PCA II doesn’ttrigger an interrupt on some PC mother boards. This problem can be fixed by changingthe value of the resistor labeled R12 on the “PCA2 Memory Card” circuit diagram.This resistor is located near the lower left corner of the main board whenviewed from the component side with the connector fingers pointing down and theinput BNC to the right. R12 is about a centimeter down and to the left of the U26 IC.The circuit diagram indicates the resistor’s value is 2K, however the boards seem tobe shipped with a 1K resistor (brown-black-red stripes). Soldering a second 1K resistoralongside R12 and in parallel electrically will lower the resistance to 0.5K, whichseems to work. (This modification was suggested by the manufacturer.)FunctionsThe mca_par() function controls the board’sbehavior as follows:mca_par("clear") — clears the channels of the current group.mca_par("run") — programs the board with the current parameters and starts acquisition.Note that the tcount() and mcount() functions, as used in the variouscounting macros will also start PCA II acquisition.mca_par("halt") — stops acquisition. Note that the PCA II will also be halted whenthe tcount() and mcount() functions, as used in the various counting macros,complete their count intervals or are aborted.mca_par("group_size") — returns the current group size.INTERIM WORK-IN-PROGRESS (8/16/01) NOT FOR GENERAL DISTRIBUTION HARDWARE REFERENCE 263