Sensoray 621 - Manual (Page 10)

Sensoray Model 621/721 Instruction Manual Page 8
6. Interrupts
6.1 Overview
I/O channels 0-63 may be individually programmed to request interrupt service upon capture of a
selected edge. A channel must have its interrupt enabled before it will generate an interrupt in response
to a captured edge. When an interrupt occurs the interrupt service routine needs to check all of the
interrupt flags as there may be more that one pending DIO interrupt.
6.2 DIO Interrupt Enable/Disable
DIO channels may be individually programmed to request interrupt service upon capture of a detected
edge. Modify a channel’s interrupt enable by writing a one to the corresponding interrupt enable
register. Set the associated bit in the Interrupt Enable register to zero or one to disable or enable,
respectively, the channel’s interrupt.
6.4 Global Interrupt Enable/Disable
Clearing this bit in the DDR/Misc. register will disable all interrupts simultaneously. Setting the bit will
allow enabled interrupts to generate a system interrupt. When GIE is disabled, interrupts are prevented
from reaching the PCI bus host, regardless of other Model 621/721 interrupt enable states (i.e. I/O
channel interrupt enables). If interrupts are to be recognized, GIE must be enabled.
6.5 Interrupt Request Flags
A one in the Interrupt Flag register indicates that an interrupt has occurred on the associated channel.
6.3 Clearing an Interrupt Request Flag
A channel’s interrupt request flag is cleared by clearing its associated capture register. This is
accomplished by clearing the associated Arm Capture register. See the section Clearing Captured Edges.