23
Chapter 3
3.4.5 Interrupt Triggering Edge Control
The interrupt can be triggered by a rising edge or a falling edge of the
interrupt signal, selectable by the value written in the "triggering edge
control" bit in the interrupt control register, as shown in Table 3-4.
3.4.6 Interrupt Flag Bit
The "interrupt flag" bit is a flag indicating the status of an interrupt. It is
a readable and writable bit. Read the bit value to find the status of the
interrupt, write "1" to this bit to clear the interrupt. This bit must be
cleared in the ISR to service the next incoming interrupt.
Table 3.4: Triggering edge control bit values
E0 or E1
Triggering edge of interrupt signal
1
Rising edge trigger
0
Falling edge trigge
Table 3.5: Interrupt flag bit values
F0 & F1
Interrupt status
Read
1
Interrupt exists
0
No interrupt
Write
1
Clear interrupt
0
Don't car
Summary of Contents for PCI-1751U
Page 1: ...PCI 1751U 48 bit Digital Input Output Card with Universal PCI Bus User Manual ...
Page 5: ...2 CHAPTER 1 General Information ...
Page 9: ...2 CHAPTER 2 Installation ...
Page 15: ...11 Chapter2 2 5 PCI 1751U Block Diagram Figure 2 2 PCI 1751U Block Diagram ...
Page 18: ...PCI 1751U User Manual 14 ...
Page 19: ...2 CHAPTER 3 Operation ...
Page 28: ...PCI 1751U User Manual 24 ...
Page 29: ...2 APPENDIX A Function of 8254 Counter Chip ...