RTD Embedded Technologies, Inc.
|
www.rtd.com
61
DMx820 User’s Manual
WIDTH[15:0]
RW,+0
Field
Description
WIDTH[15:0]
The width of the output:
Frequency
Clock
Width
WIDTH
_
_
6.3.9
82C54
T
IMER
C
OUNTER N
The following section is taken from the MSM82C54 Datasheet from Oki Semiconductors. For information on programming the 82C54 timer
counters, please consult the datasheet.
DESCRIPTION OF OPERATION
MSM82C54-2 functions are selected by control words from the CPU. In the required program sequence, the control word setting is followed by
the count value setting and execution of the desired timer operation.
Control Word and Count Value Program
Each counter operating mode is set by control word programming. The control word format is outlined below.
Table 12: Select Counter SC[1:0]: Selection of set counter
SC[1:0]
Set Contents
00
Counter #0 Selection
01
Counter #1 Selection
10
Counter #2 Selection
11
Read Back Command
Table 13: Read/Load RL[1:0]: Count Value Reading/Loading format setting
RL[1:0]
Set Contents
00
Counter Latch Operation
01
Reading/Loading of Least Significant Byte (LSB)
10
Reading/Loading of Most Significant Byte (MSB)
11
Reading/Loading of LSB followed by MSB
Table 14: Mode M[2:0]: Operation waveform mode setting
M[1:0]
Set Contents
Min Count
Value
Max Count
Value
000
Mode 0 (Interrupt on Terminal Count)
1
0
001
Mode 1 (Programmable One-Shot)
1
0
x10
Mode 2 (Rate Generator)
2
0
x11
Mode 3 (Square Wave Generator)
2
0
100
Mode 4 (Software Triggered Strobe)
1
0