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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 fX = 4.19 MHz. With fX = 6.0 MHz
operation of the
µ
PD754244 and fCC = 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
.
.