Specifications

VXIbus Interface

MODID / Interrupt Gen Reg MO04 MO03 MO02 MO01 MO00 Interrupt-out 8158

This register serves two purposes: driving the VXI MODID lines and generating a

VXI interrupt.

If the three low-order bits are not 000, one of the seven VXI interrupt lines is asserted

by the EPC-7. The line is the decoded value of these three bits (e.g., 001 denotes

IRQ1, 111 denotes IRQ7). If and when an interrupt acknowledge cycle is sent to the

EPC-7, the Interrupt-out bits are cleared. Software can also deassert an asserted

interrupt by clearing these bits at any time. A reset of the EPC-7 or setting bit RSTP

in the status/control register clears the Interrupt-out bits.

The MODID bits are explained in the context of the following register.

MODID Upper Register MO12 MO11 MO10 MO09 MO08 MO07 MO06 MO05 8159

This register and the previous one drive and sample the LBUSA local bus signals on

the VXI P2 connector. When the EPC-7 is installed in slot 0, these signals are the

MODID signals on the VXI backplane. The bits named MO00-MO12 are associated

with signals MODID00-MODID12.

When a write occurs to this register (8159), the EPC-7 drives the MODID signals on

the backplane. A read of this register (8159) terminates the driving of the signals; the

value returned from this "driver-terminating" read is not specified and should not be

used. All other reads of both registers sample the MODID signals from the

backplane. A reset of the EPC-7 or setting bit RSTP in the status/control register

terminates driving of the MODID lines.

TTL Trigger Drive Register TTD7 TTD6 TTD5 TTD4 TTD3 TTD2 TTD1 TTD0 815A

This read/write register drives the VXI TTL trigger lines; a 1 bit causes the associated

trigger line to be asserted. The actual change in state to the trigger lines is synchro-

nized to the 10 MHz CLK10 to support the VXI trigger start/stop protocol. Reading

this register does not sample the triggers; it simply returns what was previously stored

in this register. Sampling the trigger lines is performed with register 8156.

A reset of the EPC-7 clears this register.

Page 61

Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com