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Chapter 1
Hardware Description
1.3 The AM 9513 Counter Chip
The AM 9513 counter chip contains five high-speed counters
which can be programmed to perform various counting and
scaling functions. A general description for each of the 16-bit
registers that control these counters is given below.
1.3.1 Master Mode Register (AM 951 3)
The Master Mode register (MM) is used to enable and perform
special functions which are common to each individual
counter. There is one master mode register for all five counters.
These functions include:
W
Defining and enabling the inputs, outputs, and scaling factor
for Scaler 2. This is the main function of the MM register
W
Providing an enable bit for the output of Scaler 2. The
output of Scaler 2 will be referred to as FOUT
W
Providing enable bits for the two comparators that are
available for Counters 1 and 2
Providing a bit to select the operating mode of Scaler 2.
Either binary scaling or BCD scaling is allowed
B Providing two bits which are used to control and enable
the real-time clock function
1.3.4 Hold Register (AM 9513)
There is one Hold register (H) for each of the five counters.
The Hold register is used as a storage buffer for the counter
value. The contents of the counter will be transferred to the
Hold register via a software command. This feature allows the
user to check the current value of the counter without
interrupting the counting operation.,
The Hold register cannot be read directly; its data is first
transferred to the result of counter register. You must then
read the result of counter register to retrieve the value stored
in the Hold register. The result of Counter register is described
in Section 1.5.1.
1.3.5 Alarm Register (AM 951 3)
There are two Alarm registers (A); one for Counter 1, and one
for Counter 2. The Alarm register is used in conjunction with
the comparators available to Counters 1 and 2. The Alarm
register.is used to store the value which will be compared
with the counter value. If the comparator is enabled in the
Master Mode register, the output of the counter will become
active only when the Alarm -register value equals the counter
value. The Alarm register may also be referred to as the
Interrupt register.
1.3.2 Counter Mode Register (AM 9513)
There is one Counter Mode register (CM) for each of the five
1-4 6ES5-242 Module Registers
counters. The counter mode registers are used to provide
The 6 ~ ~ 5 - 2 4 2
module has several registers which are not
control, setup, and operation of each individual counter.
found in the AM 9513 or the AM 9519 chips. These registers
These functions include:
are used for various functions which are not available on the
W
Providing four bits to select one of 16 available pulse
AM 9513 or the AM 9519, but are necessary for the operation
sources to the counter
of the AM 9519, but are necessary for the operation of the
W
Providing a bit to enable or disable the gate control functions
module. A brief description of these registers is presented.
W
Providing three bits to select the operating mode of the
1-4.1 mntrOl ~
~
~
i
~
aate control function
-
The Control register (CTRL) is used to control various functions
Providing a bit to select the counting pulse edge, either
and counter selections
of
the AM 9513. This register is not
rising or falling edge
+ @
normally addressed directly by the user; the function blocks
W Providing a bit to select one of two registers from which
used to communicate with the 6ES5-242 module will handle
the counter value can be loaded
any data transfers to this register. These functions include:
W Providing a bit to select one of two counting modes, either
W Providing three bits to select from one of eight possible
continuous or onecycle mode
chip operations which include: parameter assignment,
W Providing a bit to select the counter's operating mode, either
counter manipulation, and selection of additional functions.
binary or BCD counting
W
Providing five bits, one for each counter, which are used
Providing a bit to select the counting direction, either up
counting or down counting.
to specify which counter or counters are to be involved in
the operation selected by the other three bits of the register.
W Providing three bits to select the output configuration of
the counter
1.4.2 Function Number Register
The Function Number Register (FNR) is used to identify the
1.3.3 Load Register (AM 9513)
user-stored functions. These functions can be stored on a
4K byte EPROM.
There is one Load register (L) for each of the five counters.
The Load register is used to provide the counter with a preset
count value which is set by the user.
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