rtd DM5816, Руководство пользователя

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DM5816/DM6816 RTD Embedded Technologies, Inc.
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Chapter 3 – Hardware Description
This chapter describes the features of the DM5816 hardware. The major circuits are the incremental
encoders and the timer/ counters.
The DM5816 has two major circuits, the pulse width modulators and the timer/counters. Figure 3-1
shows the block diagram of the module. This chapter describes the hardware which makes up the major
circuits.
Fig. 3-1 – DM5816 Block Diagram
Pulse Width Modulators
The DM5816 has three pulse width modulator circuits. Each circuit has one 8-bit up/down counter and
three 8-bit compare registers to generate the PWM output. Twelve digital output lines are available for
control functions (see I/O connector pinout diagrams in Appendix B).
Timer/Counters
An 8254 programmable interval timer provides three 16-bit, 8-MHz timer/counters to support a wide
range of timing and counting functions. Figure 3-2 shows the timer/counter circuitry.
Each 16-bit timer/counter has two inputs, CLK in and GATE in, and one output, timer/counter OUT.
Each can be programmed as binary or BCD down counters by writing the appropriate data to the
command word, as described in Chapter 4. The command word also lets you set up the mode of
operation. The six programmable modes are:
Mode 0 Event Counter (Interrupt on Terminal Count)