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Chapter 3
3.3 Timer/Counter Operation
3.3.1 Introduction
The PCI-1751U includes one 8254 compatible programmable timer/
counter chip which provides three 16-bit counters, designated as Timer 0,
Timer1 and Counter 2. Each has 6 operation modes. Timer 0 and Timer
1 can be used separately or can be cascaded to create one 32-bit timer.
Both Timer 1 and Counter 2 can generate interrupts to the computer.
Please refer to Appendix A for more information on the operation modes
of the counter chip. The block diagram of the timer/counter system is
shown in Figure 3-2.
Figure 3.2: Timer & Counter Structure
3.3.2 Timer 0 & 1: Two 16-bit Timers or One 32-bit Timer
Timer 0 and Timer 1 of the counter chip can be used separately or can be
cascaded to create a 32-bit programmable timer by setting jumper JP2.
By setting the clock source of Timer 1 to be an external source, you can
user Timer 0 and Timer 1 as two separate 16-bit timers. By setting the
clock source of Timer 1 to be the output of Timer 0 (internal source) these
two timers are cascaded to become one 32-bit timer.
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 ...
