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SYS"rEM TIMING C:ONTROLLER PROGRAMMING
An
Am9513
system timing controller is used to provide the timing and
counting functions performed by the
Am96/4116.
The System Timing
Controller
contains
many
control
elements
that
allow
it
to
be
customized
for
pay'ticular
applications
as
well
as
dynamically
reconfigured under program contro·l. These control
elements, which
include comparators, registers, and counters, are summarized in table
3-3.
Most of the registers can be both written to and read from under
host processor contl"ol.
Control el ements within the system timing
controller are accessed by hexadecimal address FFD2.
Data Pointer Co
Counter Mode Re
Counter Load Re
General Counter
LEMENT
BIT SIZE
QUANTITY
Bit
1
5
unter
4
1
unter
5
1
6
1
r
8
1
ng Counter
16
1
istcr
16
1
16
2
16
2
gister
16
5
gi ster'
16
5
gister
16
5
16
5
Counter Hold Re
Alarm Register
Comparator
Status Register
Output Control
FOUT Divider Co
TABLE
3-3.
CONTROL ELEMENT
SUM~·1ARY
CONTROL E
Command Reg"j ste
Frequency Seal i
Master Mode Reg
COMMAND REGISTER
Direct host processor software control
over many general
counter
funct ions is provi ded by the 8-bi t command regi ster. The host CPU
accesses the command register by performing an I/O write to hex address
FFD2~
Command register codes and a brief description of each function
is presented in tab 1e
3-04.
Si x of the command types are used for
direct software control of the counting process and they each contain a
3-17
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