CHAPTER 6 PERIPHERAL HARDWARE FUNCTION
168
User’s Manual U10676EJ3V0UM
(3) Application of CG mode
To use the timer counter as a carrier generator for remote controller signal transmission
The examples shown below apply to the operation of the
µ
PD754244 at f
X
= 4.19 MHz. With f
X
= 6.0 MHz
operation of the
µ
PD754244 and f
CC
= 1.0 MHz operation of the
µ
PD754144, the cycles and signal output
periods are different even if the settings are the same.
<1> To generate a carrier clock with a frequency of 38.0 kHz (cycle of 26.3
µ
s) and a duty factor of 1/3
•
Set the higher 4 bits of the timer counter mode register (TM2) to 0011B and select 61.0
µ
s as the
longest set time.
•
Set the lower 4 bits of TM2 to 1111B, and select the CG mode and count operation. Then, issue
the timer start command.
•
Set the timer counter output enable flag (TOE2) to “1” to enable timer output.
•
Set the high-level period setting timer counter modulo register (TMOD2H) as follows.
– 1 = 36.8 – 1
36 = 24H
•
The set value of the timer counter modulo register (TMOD2) is as follows.
– 1 = 73.7 – 1
73 = 49H
<Program example>
SEL
MB15
;
or CLR1 MBE
MOV
XA, #024H
MOV
TMOD2H, XA
;
Sets modulo (high-level period)
MOV
XA, #49H
MOV
TMOD2, XA
;
Sets modulo (low-level period)
MOV
XA, #00111111B
MOV
TM2, XA
;
Sets mode and starts timer
1
26.3
µ
s
3
238 ns
2
26.3
µ
s
3
238 ns
.
.
Содержание PD754144
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