Manual Number: 00650-014-4
Page 1-2
AD12-8 Manual
Counter/Timer
The AD12-8 includes a type 8253 counter/timer which has three 16-bit programmable synchro-
nous down counters. This chip is used for event counting, pulse and waveform generation, fre-
quency and period measurement etc. A/D conversion cycles may be initiated by the Counter/Timer
by installing the TMR/EXT jumper in the TMR position. Counter #1 is connected to a 1/32 mul-
tiple of the computer color Oscillator clock (14.31818MHz). The output of counter #1 is used as
the clock for Counter #2 and also Counter #0 when so configured by installing the CLK0 jumper.
Counter #0 is fully accessible for general purpose use.
Interrupts
Interrupts are supported from either external inputs or A/D conversion completion. Selection of
the interrupt source and interrupt levels (IRQ2-7), is made by jumper. Interrupts are software
enabled and disabled. An interrupt request may be canceled by one or more of the following three
signals:
a. The computer reset signal.
b. The beginning of an A/D conversion cycle.
c. The writing of a command word to the card. That is, either updating the gain or channel
selection multiplexer on the AT16-P expansion card, or the AD12-8 multiplexer.
Utility Software
Utility software included with the AD12-8 is provided in MS-DOS format on a diskette. A pro-
gram named FINDBASE can help you to select the base address for the card. Two menu-driven
setup programs, DOS drivers in linkable object form and binary form, a VisualBASIC utility driver,
and sample programs are provided. One setup program is a configuration and calibration tool for
the AD12-8, and the second setup program is used when an AT16-P and/or LVDT8-P is used in
conjunction with the AD12-8. In the case of the AT16-P, gains are assignable on a channel-by-
channel basis. Linearization for all the commonly used thermocouple types as well as for platinum
RTDs is also menu selectable.
A driver configuration file is generated or modified by the setup program and can be used to
configure the AD12-8 driver.
CHAPTER 2: SYSTEM SOFTWARE
describes the format of this
configuration file. This driver has 17 Tasks as will be described in detail in
CHAPTER 5: AD12-
8 DRIVER REFERENCE
of this manual.
Sample programs are provided in BASIC, QuickBASIC, Pascal and C.
